Available online at website: https://journal.
id/index.
php/bcrec Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
2026, 244-261 Review Article Modification Strategies of Copper Molybdate-based Photocatalysts for Degradation of Organic Compounds in Wastewater: A Mini Review Hamidah binti Abdullah1.
Rohayu binti Jusoh1.
Wahaizad bin Safie2.
Ricca Rahman binti Nasaruddin3.
Maksudur Rahman Khan4.
Md Noor bin Arifin1* 1Faculty of Chemical and Process Engineering Technology.
Universiti Malaysia Pahang Al-Sultan Abdullah, 26300 Gambang.
Pahang.
Malaysia.
2Faculty of Manufacturing and Mechatronic Engineering Technology.
Universiti Malaysia Pahang Al-Sultan Abdullah, 26600 Pekan.
Pahang.
Malaysia.
3Department of Biotechnology Engineering.
Kulliyyah of Engineering.
International Islamic University, 50728 Kuala Lumpur.
Malaysia.
4Petroleum and Chemical Engineering Programme.
Faculty of Engineering.
Universiti Teknologi Brunei.
Jalan Tungku Link Gadong.
BE1410.
Brunei Darussalam.
Received: 6th January 2026.
Revised: 14th January 2026.
Accepted: 15th January 2026 Available online: 28th January 2026.
Published regularly: August 2026 Abstract Visible-light photocatalysis has emerged as a sustainable tertiary-treatment option.
Within this arena, copper molybdate (CuMoO.
is attractive because of its narrow bandgap enables direct solar harvesting while relying on earthabundant elements.
Yet pristine CuMoO4 suffers from low surface area (< 10 m2/.
, rapid electron-hole recombination and Cu2 photocorrosion, which curb quantum yields and raise secondary-pollution concerns.
This mini review critically synthesizes research published between 2019 and 2025 on strategies devised to surmount these limitations.
Four major areas are surveyed: .
morphology engineering that multiplies active-site density and deepens light scattering.
plasmonic or single-atom noble-metal decoration that extends spectral response and accelerates interfacial charge separation via localized surface plasmon resonance.
band-gap and defect modulation through doping or oxygenvacancy creation, narrowing band gap and introducing long-lived trapping states, and .
construction of p-n heterojunctions .
ZnO/CuMoO4, graphitic carbon nitride/copper molybdate .
-C3N4/CuMoO.
that yield order-ofmagnitude rate enhancements by spatially separating redox half-reactions.
The synthesis approaches, from hydrothermal and co-precipitation to thermal-decomposition and solid-state reactions directly influence crystallinity, morphology and defect chemistry, with optimal hydrothermal conditions .
oC, 10 .
producing high-purity CuMoO4 microspheres and oxygen-vacancy-rich Cu-rich phases delivering up to a 0.
5 eV bandgap reduction.
Emphasis is placed on correlating structural descriptors with pollutant-mineralization kinetics and on emerging green-synthesis Remaining challenges and research priorities including stability against Cu leaching, scalable fabrication and in-situ mechanistic probes are highlighted to guide future catalyst design.
Copyright A 2026 by Authors.
Published by BCREC Publishing Group.
This is an open access article under the CC BY-SA License .
ttps://creativecommons.
org/licenses/by-sa/4.
Keywords: Visible-light Photocatalysis.
Copper Molybdate.
Morphology Engineering.
Defect Modulation.
Heterojunctions How to Cite: Abdullah.
Jusoh.
Safie.
Nasaruddin.
Khan.
Arifin.
Modification Strategies of Copper Molybdate-based Photocatalysts for Degradation of Organic Compounds in Wastewater: A Mini Review.
Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 244-261.
(DOI:
9767/bcrec.
Permalink/DOI: https://doi.
org/10.
9767/bcrec.
Introduction The presence of biologically active and chemically resilient organic pollutants in municipal and industrial wastewater has become * Corresponding Author.
Email: noormd@umpsa.
my (M.
Arifi.
a critical environmental challenge over the past endocrine-disrupting chemicals and synthetic dyes now being detected worldwide in final effluents .
Persistence arises from aromaticity, halogenation and other substituents that confer resistance to biodegradation and direct photolysis, so that even advanced biological plants hardly bcrec_20627_2025 Copyright A 2026.
ISSN 1978-2993.
CODEN: BCRECO
Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 245 remove many antibiotics and hormones .
Toxicological 17-ethinylestradiol can trigger intersex conditions in fish at 1 to 5 ng/l and sulfonamide antibiotics inhibit algal growth at only a few AAg/l, demonstrating that trace concentrations are sufficient to impair aquatic ecosystems .
Visible-light photocatalysis is therefore regarded as a promising tertiary treatment because roughly 45 % of the solar spectrum lies in the 400 - 700 nm range that can be harvested without artificial irradiation .
Among recently explored semiconductors.
CuMoO4 has attracted attention for its narrow 1.
0 eV band gap .
, cost effective .
and its ability to exist in various states .
, positioning it as a candidate for sustainable solar-based advanced oxidation Although benchmark materials, such as anatase TiO2 with a band gap of 3.
2 eV .
and ZnO, can fully mineralize model dyes under ultraviolet lamps, their activity drops sharply under simulated sunlight because only about 5 % of terrestrial irradiance is UV .
By contrast.
CuMoO4 degraded rhodamine-B (RhB) 1.
39 times faster than N-doped TiO2 and achieved 1.
53-fold higher total organic carbon removal under the same visible-light conditions .
A hydrothermal Aupebble-stoneAy CuMoO4 removed 94.
7 % of methylene blue (MB) in 50 min, outperforming pristine ZnO and matching the best bismuth vanadate (BiVO.
reports under identical photon flux .
Nevertheless, intrinsic limitations The conduction-band edge of CuMoO4 .
3 to 0.
4 V vs Normal Hydrogen Electrode (NHE)) is only marginally negative to the O2/O2A- couple, restricting its reduction power, while the valence band ( 1.
5 to 1.
7 V) is insufficient to oxidize water to hydroxyl radicals .
Consequently, superoxide anion becomes the dominant reactive oxygen species generated, which can slow mineralization of highly halogenated or polyaromatic contaminants .
In addition.
CuMoO4 combustion or solid-state routes exhibit specific surface areas below 10 m2/g, leading to poor agglomeration that retard interfacial kinetics .
Moreover, as with other Cu-oxides, prolonged irradiation can trigger photocorrosion and Cu2 leaching, posing secondary pollution risks if protective measures are not implemented .
To address these drawbacks, researchers have investigated a spectrum of modification Comparative studies in the recent literature reveal distinct trade-offs between these modification approaches.
While elemental doping, such as the incorporation of yttrium (Y) into the CuMoO4 lattice, has been shown to effectively narrow the bandgap from 1.
44 eV to 1.
39 eV and increase charge migration by five-fold .
, it is often limited by the thermodynamic solubility of the dopant and potential leaching during longterm operation .
In contrast, the construction of heterojunctions generally offers superior stability and charge separation efficiency.
For instance, recent work on Type-II heterojunctions.
CuMoO4/Bi2S3, degradation efficiency of 98% for organic dyes, nearly double that of pure CuMoO4 .
%) under identical solar irradiation .
Furthermore.
S-scheme ZnMoO4/ZnIn2S4 evolution rates over 10 times higher than their individual components by preserving high-redoxpotential charge carriers, a feat that simple morphology engineering alone cannot achieve .
Thus, while morphology control provides necessary surface active sites, integrating it with heterojunction engineering represents the current frontier for maximizing quantum efficiencies in molybdate-based photocatalysts.
ZnO/CuMoO4 g-C3N4/CuMoO4 heterojunctions lengthen charge-carrier lifetimes and extend spectral utilization, enabling 92 % MB removal in 70 min and seven-fold acceleration of tetracycline degradation relative to the single components .
Morphology engineering ranging from 45 m2/g nanorods to hollow urchin-like microspheres with multiplies active-site density and augments light scattering for deeper photon capture .
Against this backdrop, a comprehensive synthesis of literature on CuMoO4 modification is urgently needed to guide rational materials design and accelerate translation from bench to practice.
A summary of modification techniques is presented in Figure 1.
The present mini review therefore collates advances published Figure 1.
Schematic illustration of the four primary modification strategies for CuMoO4based photocatalysts reviewed in this work:
control, noble metal plasmonic decoration (LSPR), and doping/co-doping.
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 246 between 2019 and 2025, critically examines how each structural or compositional intervention influences light harvesting, charge separation, interfacial redox chemistry and concludes with prioritized research directions.
Photocatalytic Degradation Mechanisms over Copper Molybdate Photocatalyst CuMoO4 has long been recognized as a photochemically versatile oxide whose mixedmetal framework couples a narrow visible-light band gap with a redox-flexible Cu2 /Cu sublattice.
In its most studied triclinic -phase, whose crystal growth and properties were first detailed in 1968 .
and structure determined shortly thereafter .
, the valence band is dominated by O 2p states that hybridize with Mo 4d and Cu 3d The conduction band is mostly made up of Mo 4d orbitals, making the material with appreciable absorption of the solar spectrum .
To better understand the mechanism of photocatalytic degradation of organic molecules over CuMoO4 photocatalyst, a study was chosen to demonstrate the steps and details of the analytical results such as radicals and mass spectrometry experiments .
MB was commonly selected as a benchmark contaminant because its chromophore structure is highly sensitive to radical attack, allowing precise tracking of reactive oxygen species .
Upon light irradiation.
CuMoO4 photocatalyst generate superoxide radicals (O2A-), hydroxyl radicals (NOH), electrons .
-) and holes .
), which can oxidize organic contaminants to CO2 and H2O.
To elucidate which of these species drive MB degradation by CuMoO4 photocatalyst, trapping experiments were conducted in an aqueous MB suspension containing 0.
CuMoO4, in the presence of light and specific benzoquinone (BQ) for O2A-, isopropyl alcohol (IPA) for NOH, silver nitrate (AgNO.
for eA (EDTA-2N.
for h and the experiments were monitored spectrophotometrically.
The inhibition by BQ and IPA indicates that photogenerated superoxide and hydroxyl radicals are the main oxidizing agents, while the minimal impact of AgNO3 and EDTA-2Na demonstrates that electrons and holes play a secondary role.
These photocatalysis via OCCA- and NOH is the dominant pathway for MB mineralization, consistent with reports in the literature and, together with the bandAaedge positions of 0.
3 M CuMoO4 photocatalyst, support the proposed mechanism .
for charge separation and subsequent photocatalytic degradation of MB under sunlight irradiation, as follows:
CuMoO4 h Ie e- h e- O2 Ie O2A(H2O NI H OH-) h Ie H NOH MB O2A-/NOH/h Ie intermediates Ie degradation products .
Liquid-chromatography mass spectrometry (LC-MS) revealed several transient species (Figure 2.
), whose molecular structures were assigned from their characteristic mass-to-charge Under sunlight irradiation.
MB (MB, m/z = .
undergoes a stepwise photocatalytic degradation in water, generating a succession of Figure 2.
Liquid-chromatography mass spectrometry (LC-MS) analysis of Methylene Blue (MB) Panels show .
the mass spectrum of the initial MB dye .
/z = .
, .
the spectrum of degradation intermediates after irradiation, and .
the proposed degradation pathway involving ring opening and bond cleavage steps .
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 247 increasingly simple, environmentally benign The pathway outlined in (Figure 2.
), begins with rupture of the N=N double bond, followed by benzene-ring opening and sequential cleavage of C-N.
C-C and finally C-S bonds that connect the aromatic core to its sulfonate Together these transformations account for the complete mineralization of MB into harmless end-products.
Modification Strategies of CuMoO4-based Photocatalysts CuMoO4 possesses an ability as a semiconductor to photodegrade organic dyes, but its baseline activity leaves room for improvement.
To enhance performance and better utilize solar spectrum, various modification strategies have been developed.
Below, we review key modification approaches, from morphology control to heterojunction formation, as explicitly described in the literature, along with their impacts on photocatalytic degradation of persistent organics.
1 Morphological Control Controlling the crystallite size and shape of CuMoO4 can influence its surface area, light absorption and reactive facet exposure .
Hydrothermal temperature tuning is one of the effective routes .
It was observed that raising the hydrothermal synthesis temperature to 200 oC yielded CuMoO4 particles that were rounded and tiny (See Figure 3 .
), indicating a temperaturedirected refinement of primary crystallites .
The rounding effect at higher temperature was correlated with improved photocatalytic efficiency with the optimum temperature at 180 oC, due to more uniform morphology and phase purity.
Figure 3 .
reveals that pristine CuMoO4 forms granular aggregates that coalesce into dense clusters.
Extending the hydrothermal treatment gradually smooths these grains, yielding increasingly rounded particles with Meanwhile, a sonochemical synthesis has shown an ability to produce ultra-small CuMoO4 CuMoO4 was prepared via a surfactant-free sonochemical route, resulting in roughly spherical nanoparticles from 50 to 55 nm in diameter .
The scanning electron microscopy (SEM) images confirmed the particles to be round, about 50-55 nm in size.
These nanocrystals showed a higher photocatalytic degradation of methyl orange, close to 72 % under UV in 60 min, compared to bulk CuMoO4, which the author attributes to the favourable nanoscale morphology .
igh surface-to-volume rati.
Tailoring CuMoO4 morphology, via hydrothermal or sonochemical method can be considered as an accessible modification strategy to expose more active sites.
However, morphology alone may yield only moderate activity gains, for example through incremental increase in dye removal, and often needs to be combined with other modifications for substantial improvements.
2 Noble-Metal Plasmonic Decoration (LSPR) Loading of noble metals introduces localized surface plasmon resonance (LSPR) effects that extend light absorption into the visible range and promote charge separation .
Cu2MoO4 was decorated with Ag nanoparticles (Ag/Cu2MoO.
and demonstrated plasmon-enhanced visiblelight harvesting .
, confirmed by the X-ray photoelectron spectroscopy (XPS) analysis.
Under visible illumination, the Ag/Cu2MoO4 composite achieved 99.
7 % degradation of malachite green (MG) in 50 min, whereas bare Cu2MoO4 reached 83.
6 % within the same testing This performance can be attributed to the LSPR of Ag.
The Ag-decorated catalyst exhibited strong visible-light absorption due to collective oscillation of Ag conduction electrons, which accelerates the separation between the generated e- and h in CuMoO4, as depicted in Figure 4.
Figure 3.
SEM micrographs illustrating the morphological evolution of CuMoO4 synthesized via the hydrothermal method with .
shows the effect of reaction temperature .
p to 200 oC for 10 hour.
leading to particle rounding, and .
shows the effect of reaction time .
to 14 hours at 180 oC) on grain smoothing and cluster formation .
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 248 Furthermore, electrochemical tests, such as electrochemical impedance spectroscopy (EIS) and photocurrent showed Ag/Cu2MoO4 had a smaller charge-transfer resistance and higher photocurrent than CuMoO4, indicating more efficient charge separation.
The Ag nanoparticles also slightly narrowed the effective band gap of Cu2MoO4, enabling excitation by longer It should be noted that noble-metal decoration introduces cost and potential stability issues .
, owing to the fact that Ag may oxidize or aggregate over time, even though it clearly improves visible-light activity.
CuMoO4, with < 2 % Ag triples photocurrent, delivers 100 % dye removal in 50 min and retaining > 95 % activity over five cycles, providing a compelling benchmark for CuMoO4 modification strategies .
3 Doping and Co-doping Introducing additional cations or anions into CuMoO4 can alter its electronic structure, create defect sites and improve catalytic performance .
Heteroatom doping as a solid solution has been demonstrated on CuMoO4 within an AlPO4 host lattice .
A copper-molybdate-doped aluminum phosphate, denoted CuxMoxAl1CUxP1CUxO4, via a solid-solution method.
X-ray diffraction (XRD) Fourier spectroscopy (FTIR) confirmed formation of a single-phase mixed oxide with Cu and Mo substituting into the lattice structure of AlPO4.
Among various metal molybdate-doped AlPO4 samples, the Cu-containing solid solution at x = 5 showed the best activity for photoreduction of Figure 4.
Schematic mechanism for the photocatalytic degradation of Malachite Green (MG) over Ag-decorated Cu2MoO4.
The diagram highlights the Localized Surface Plasmon Resonance (LSPR) effect of Ag nanoparticles, which extends visible-light absorption and accelerates electron-hole separation .
nitroaniline pollutants under UV-visible light This CuMoO4/AlPO4 composite exhibited semiconductor behavior with an expanded band gap of 4.
21 eV and intense photoluminescence at 271 nm.
The wide band gap and high-energy emission stem from the host AlPO4 matrix, while the presence of CuMoO4 imparts visible-light response and catalytic sites.
Thus, by co-doping Cu and Mo into AlPO4, a new heterostructure was achieved where the CuMoO4 functionality and AlPO4 stability yield a robust UVAevisible active catalyst.
In addition to foreign dopants, intrinsic Cu enrichment in CuMoO4 itself can also introduce beneficial defects .
Cu precursor concentration .
1, 0.
2, 0.
3 M) was varied in a thermal decomposition synthesis of CuMoO4 and a systematic change was observed in the properties of the material.
All samples remained phase-pure CuMoO4, but increasing Cu content led to enlarged crystallite size, from 41 nm to 50 nm, when increased from 0.
1 M to 0.
3 M respectively, and notable electronic modifications.
Specifically, the band gap of CuMoO4 narrowed from 1.
97 eV .
1 M) to 1.
44 eV .
3 M).
This 0.
5 eV band gap reduction implies that excess Cu created mid-gap impurity levels or defect states .
Additional Cu atoms likely occupy interstitial or substitutional sites in the MoO4 lattice, which alter the normal lattice structure and introduce electronic states between the valence and conduction bands .
Evidence of these defect states is a new broad absorption feature around 600 nm in the UVvisible spectra of Cu-rich samples as shown in Figure 5.
Figure 5.
UVAevisible absorbance spectra of CuMoO4 nanoparticles synthesized with varying copper precursor concentrations .
3 M).
Note the emergence of a broad absorption feature around 600 nm and the narrowing of the band gap .
97 to 1.
44 eV) in the Cu-rich 0.
3 M sample, attributed to oxygen-vacancy induced defect states .
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 249 This 600 nm feature was attributed to a plasmon-like resonance of conduction-band electrons in oxygen-deficient CuMoO4.
In other words.
Cu excess doping induced oxygen vacancies or Cuo nanoclusters that give a LSPR .
nalogous to noble metal.
at 600 nm .
Such defects also improved charge carrier dynamics .
The 0.
CuMoO4 showed much lower photoluminescence .
electron-hole recombinatio.
than the 0.
1 M sample.
Consequently, the photocatalytic mineralization of MB under sunlight was highest for the 0.
CuMoO4 with complete mineralization due to the increased charge-carrier density and suppressed eA/hA recombination from these introduced defect This strategy of intrinsic doping is facile by simply varying the precursor stoichiometry, but one must ensure that no secondary phases appear via XRD measurement, showed no impurity peaks up to 0.
3 M Cu .
Properly controlled, defect engineering via Cu stoichiometry can significantly visible-light photocatalytic efficiency of CuMoO4.
4 Heterostructure Construction Forming heterostructures by coupling CuMoO4 with other materials is a prominent strategy to improve charge separation and extend light absorption.
Heterojunctions can create internal electric fields that drive photogenerated electrons and holes into separate phases, thereby reducing recombination .
We discuss three sub-categories: carbon-based hybrids, binary oxide pAen junctions, and 2D carbon allotrope Each approach explicitly appears in the literature with demonstrated performance gains.
Recent high-impact reviews .
emphasize that unlike conventional Type-II systems, advanced Z-scheme and S-scheme configurations are critical for maintaining high redox potentials narrow-bandgap min by GO/TiO2 .
The GO plays a key role as a p-type semiconductor .
with abundant oxygenated groups and GO sheets serve as electron acceptors and dispersants for CuMoO4 .
Photogenerated electrons from CuMoO4 transfer to GO, where they react with dissolved O2 to produce superoxide (O2A-) radicals.
Meanwhile, the photogenerated holes remain on CuMoO4 and oxidize water or OH- to form NOH radicals.
This charge separation mechanism as illustrated in Figure 6 leads to an abundance of reactive radicals on GO-CuMoO4, whereas pure CuMoO4 suffered rapid electron-hole recombination.
Additionally, the large surface area and functional groups of GO improved dye adsorption and provided more reactive interfaces .
It was observed that increasing GO content enhanced activity up to an optimal point with 2:1 of GO: GOCuMoO4 ratio, beyond which excess GO might shield light or recombine charges.
In summary, the GO-CuMoO4 2D/0D composite demonstrates how carbon hybrids can dramatically boost photocatalytic efficiency by combining the light absorption of CuMoO4 with charge-carrier trapping of GO and pollutant adsorption abilities.
Graphitic carbon nitride .
-C3N.
is a visiblelight-active 2D semiconductor with a band gap of 7 eV .
, was deployed to form a heterojunction formation with CuMoO4 nanoflowers .
The gC3N4/CuMoO4 composite was synthesized via a one-pot Electron microscopy revealed CuMoO4 crystallites .
-15 nm petal.
intimately anchored on the g-C3N4 The g-C3N4/CuMoO4 heterostructure exhibited outstanding photocatalytic degradation efficiencies with 98 % of RhB and 97 % of ciprofloxacin antibiotic were decomposed in 35 1 Carbon-based hybrids Graphene-family carbon materials are excellent conductive supports that can accept electrons and increase adsorptive interactions .
Graphene oxide-copper molybdate (GOCuMoO.
nanocomposites was synthesized via ultrasonication and reflux methods.
In this 2D/particle hybrid.
CuMoO4 nanoparticles were dispersed on GO sheets .
The GO- CuMoO4 composite with an optimized GO:CuMoO4 ratio of 2:1 achieved 99 % MB degradation in 32 min under visible light.
Its apparent rate constant .
094/mi.
was over 30 times higher than that of pure CuMoO4 .
0029/min, only 30 % degradation in 140 mi.
However, it is noted that this performance still requires enhancement when compared to 93 % of MB degradation within 13 Figure 6.
Schematic representation of charge separation in graphene oxide (GO)-CuMoO4 Photogenerated transfer from CuMoO4 to the GO sheets .
cting as electron acceptor.
to form superoxide radicals, while holes remain on CuMoO4 to generate recombination .
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 250 and 60 min, respectively, under visible-light These results surpassed the performance of pure g-C3N4 or CuMoO4 alone.
The superior performance of g-C3N4/CuMoO4 is attributed to formation of heterojunction charge transfer mechanism.
Upon light excitation, electrons from the conduction band (CB) of CuMoO4 recombine with holes from the valence band (VB) of g-C3N4 at the interface, effectively leaving behind strong oxidation holes in CuMoO4 (VB) and strong reduction electrons in g-C3N4 (CB).
This direct mechanism preserves the high redox power of both semiconductors, unlike a conventional Type-II heterojunction.
Consistent with the scavenger protocols described in Section 2, trapping experiments on the composite confirmed that NOH and O2A- remain the primary active species, but with significantly enhanced yield due to the Z-scheme spatial separation of charge carriers.
Additionally, g-C3N4/CuMoO4 showed significantly reduced photoluminescence and a higher photocurrent than either component, reflecting efficient charge separation.
The composite was stable over 5 cycles with negligible activity loss.
g-C3N4/CuMoO4 modification with CuMoO4 extending the visible absorption of g-C3N4 into deeper wavelengths, while g-C3N4, with its conductive A-structure shuttles electrons away .
One limitation is that the synthesis requires careful control to achieve intimate contact between phases.
Otherwise, charge transfer may be insufficient .
Nevertheless, g-C3N4/CuMoO4 heterojunction strategy is a powerful way to leverage the strength of multiple semiconductors strengths in one system.
pAen heterojunctions Coupling CuMoO4 metal-oxide semiconductor can form a classic p-n junction, facilitating charge separation via the built-in electric field at the interface .
ZnO/CuMoO4 composite was fabricated using a green hydrothermal method with Bambusa vulgaris leaf extract .
Pure ZnO is n-type semiconductor with a band gap.
Eg of 3.
2 eV, primarily absorbs UV light .
, but when coupled with CuMoO4, the ZnO/CuMoO4 composite showed a broadened absorption into visible light, with a band gap of ZnO/CuMoO4 heterojunction achieved 93.
4 % dye degradation in 120 min under visible light, compared to only 55.
% by ZnO alone.
Kinetic analysis indicated a reaction rate constant 3 times higher for the ZnO/CuMoO4 composite than the bare ZnO.
The enhancement can be explained by two factors, on account of enlarged light absorption by the presence of CuMoO4 that enabled utilization of visible wavelengths .
that ZnO cannot absorb and suppressed charge recombination .
The construction of p-n junction at the ZnO/CuMoO4 interface creates an internal electric field that drives photogenerated electrons from CuMoO4 to the n-ZnO and holes from ZnO to the p-CuMoO4 .
This charge separation mechanism was evidenced by the reduction of photoluminescence and higher photocatalytic efficiency ZnO/CuMoO4 The ZnO/CuMoO4 heterostructure leveraged the complementary properties of a wide-bandgap n-type and a narrow-bandgap ptype semiconductor.
Beyond the ZnO/CuMoO4 system, recent investigations have expanded to diverse metal oxide heterojunctions to overcome the limitations of single-component CuMoO4.
A comparative analysis of these systems reveals distinct advantages depending on the band alignment strategy employed.
For instance.
TiO2/CuMoO4 composites have been shown to significantly enhance photocatalytic performance through a Type-II heterojunction mechanism.
In this configuration, the specific band alignment allows photogenerated electrons to transfer from the conduction band of CuMoO4 to that of TiO2, effectively suppressing charge recombination.
This synergy resulted in a 4-chlorophenol degradation efficiency of 96.
9 % under visible light, far surpassing pristine TiO2 .
Similarly, the coupling of CuMoO4 with Bi-based oxides, such as in the CuMoO4/Bi2WO6 system, utilizes a Z-scheme or p-n junction approach to maximize redox potential.
Studies indicate that such heterojunctions can achieve degradation rates for RhB that are nearly double those of the individual components by preserving the strong oxidative ability of holes in the valence band of CuMoO4 while facilitating electron transport .
Furthermore, recent work on Co3O4/CuMoO4 hybrid microflowers highlights the role of morphological synergy in heterojunctions.
This system utilizes the p-type conductivity of Co3O4 to create a p-n junction with n-type CuMoO4, which not only improves charge separation via an internal electric field but also lowers the activation energy for catalytic reactions.
This specific coupling has demonstrated high catalytic turnover frequencies in hydrolytic applications, suggesting its versatility for complex wastewater treatments .
In contrast, doping strategies, such as Y-doped CuMoO4, offer an alternative route by modulating the intrinsic bandgap .
owering it to 1.
39 eV) and increasing charge migration five-fold without forming a secondary phase .
Collectively, these findings suggest .
ike TiO2/CuMoO.
are effective for general organic pollutants, more complex Z-scheme or p-n junction designs .
ike Bi2WO6/CuMoO4 or Co3O4/CuMoO.
provide superior redox capabilities for recalcitrant Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 251 compounds, dictating the choice of modifier based on the specific target pollutant.
Surface-Defect Engineering Oxygen-Vacancy Creating oxygen vacancies or other surface defects on CuMoO4 can profoundly affect its optical absorption and catalytic sites.
Unlike bulk doping in Section 3.
3, this strategy focuses on generating non-stoichiometric surfaces that often exhibit color centers of F-center like behavior .
This phenomenon induces plasmonic absorption due to free electrons in vacancy sites and an example of such modulation is Cu-rich CuMoO4 photocatalysts .
It was found that the Cu1xMoO4 .
here x > .
samples contained Cu or metallic Cu and had oxygen-deficient areas.
These features caused a new light absorption band to appear around 600 nm.
The presence of these oxygen-vacancyinduced states extends the light absorption into the orange-red region and provides localized electronic states that can participate in redox reactions .
Unlike the bulk recombination limitations described in Section 2, these surface oxygen vacancies act as charge carrier traps that effectively prolong the lifetime of photogenerated electrons and holes .
In CuMoO4, an appropriate concentration of oxygen vacancies can thus improve photocatalysis by increasing visiblelight absorption and by capturing electrons or holes, to prevent premature recombination.
However, it is critical to achieve a balance because an excessive oxygen vacancy could turn CuMoO4 into a metallic, heavily carrier-damped material or create recombination centers if they aggregate .
Techniques to introduce surface oxygen vacancies include annealing CuMoO4 in a mildly reductive atmosphere or employing vacuum UV irradiation .
In summary, surface-defect engineering via Cu/Mo stoichiometry changes or reduction treatments can synthesize CuMoO4 with a plasmonic 600 nm band and enhanced visiblelight activity.
This strategy, with a proper control, complements the other modifications.
For instance, one could create oxygen vacancies in situ during the formation of CuMoO4 heterojunctions or doped systems to further boost performance.
explicitly introducing and characterizing such defects, for example via XPS O 1s peak shifts or electron paramagnetic resonance (EPR) signals, researchers can correlate defect density with photocatalytic rates.
Each modification strategy above offers distinct advantages and has certain limitations.
Morphology control is relatively straightforward but typically yields only incremental gains, it mainly optimizes surface area and facet exposure.
Noble-metal decoration introduces strong visiblelight absorption and improved charge separation via LSPR, but at the cost of using precious metals and potential stability issues, namely Ag or Au Doping co-doping fundamentally alter the band structure of CuMoO4 and create active defect sites.
This can dramatically improve performance via band gap narrowing from 1.
97 to 1.
44 eV, but unwanted phases should be avoided.
Dopants should be prevented from leaching into the solution, to align with green chemistry principles.
Heterostructure construction is arguably the most impactful strategy for boosting photocatalytic efficiency.
forming p-n junction systems, researchers have achieved order-of-magnitude increases in reaction rates .
The composite catalysts harness broader sunlight spectrum and greatly suppress charge recombination, which is reflected in superior pollutant removal efficiencies.
The tradeoff is that multi-component systems can be more complex to synthesize and optimize.
Finally, surface-defect engineering is an approach that can be used in tandem with any of the above.
Oxygen vacancies, for example, could be introduced in a CuMoO4/ZnO composite to further extend its absorption and reactivity.
When comparing across strategies, heterojunction-based modifications, especially with carbon materials or coupled semiconductors stand out for achieving the highest photocatalytic rates under visible light.
Table 1 shows the summary of modification strategies of CuMoO4-based materials and related experimental conditions for degradation of various pollutants.
Synthesis Methods of Copper Molybdatebased Materials The efficacy of CuMoO4-based materials as photocatalysts is profoundly influenced by their physicochemical properties, such as crystal structure, particle size, morphology, surface area and defect chemistry .
These properties are critically dependent on the chosen synthesis A diverse array of synthesis techniques has been explored to fabricate CuMoO4 materials with tailored characteristics suitable for photocatalytic applications.
This review section comprehensively discusses various synthesis routes reported for CuMoO4-based materials, including hydrothermal .
, co-precipitation .
, thermal-decomposition to precipitation .
and solid-state high-temperature .
The choice of synthesis technique is guided by the desired characteristics and intended applications of the CuMoO4 material.
1 Hydrothermal Method The hydrothermal method involves chemical reactions of substances in a sealed, heated aqueous solution or other solvents, above ambient temperature and pressure .
This technique Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 252 facilitates the dissolution of precursors, promotes nucleation and allows for the controlled growth of crystalline materials, often with unique morphologies .
A sea-urchin hollow CuMoO4-CoMoO4 hybrid microsphere were synthesized via a template-free hydrothermal approach .
The synthesis utilized 1 mmol of CuCl2UI2H2O, 1 mmol of CoCl2UI6H2O, and 4 mmol of Na2MoO4UI2H2O as precursors, dissolved in 30 ml of distilled water.
The mixture was stirred for 30 min, then transferred to a 50 mL Teflon-lined stainless-steel autoclave and heated at 180 oC for 12 hours.
Postsynthesis, the precipitate was collected, washed with distilled water and absolute ethanol, dried in a vacuum oven at 60 oC for 12 hours and finally calcined in air at 500 oC for 4 hours.
The resulting materials exhibited a sea-urchin like hollow microsphere morphology with numerous nanorods on the surface.
It was found that hydrothermal synthesis of CuMoO4 is optimized at the heating of 180 AC for 10 hours (Figure 7 .
) .
Below 150 AC the reaction stops at Cu3Mo2O9, which shows weak XRD peaks and hardly breaks down RhB (Figure 7 .
Above 200 AC, the crystals stop getting better and start to grow too big, so activity flattens For the photocatalytic degradation of RhB or 1H-benzotriazole, the optimal hydrothermal conditions were found to be at a temperature of 180 AC and a reaction time of 10 hours, corresponding to the high purity and highly Figure 7.
X-ray Diffraction (XRD) patterns tracking the crystallinity of CuMoO4 with .
the amorphous precursor state and .
the evolution of crystalline phases at 180 oC over different hydrothermal durations .
-14 hour.
, identifying 10 hours as the optimal duration for high-purity phase formation .
Table 1.
Summary of reported modification strategies for CuMoO4-based photocatalysts, detailing synthesis methods, target pollutants, light sources, and degradation efficiencies.
(N.
: Not Specified.
Light Initial Catalyst .
LAA)
Visible wattage not 5 y 10-6
Degradatio
(%)
CuMoO4 doped into AlPO4
2-NA/4-NA
UV-visible .
ower not One-pot Z-scheme RhB/ Ciprofloxacin Visible wattage not ZnO/CuMoO4 .
Hydrothermal microwave ZnO MB/RhB UV lamp, wattage not CuMoO4 Solid-state 550 AC Doping into Bi2Ti4O11 alloy Thymol blue UV .
amp details not CuMoO4based Synthesis Modification / ZnO/CuMoO4 Two-phase bio-interface (BVLE) ZnO CuMAP2 (CuMoO4doped AlPO.
Solid-solution CuMoO4@gC3N4 (CMC) Pollutant.
Time .
Ref.
98 / 97
92 / 84
3 ppm 50 % (T.
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 253 crystalline CuMoO4 whose exposed facets drive efficient visible-light catalysis.
In this study, the band gap of the CuMoO4 synthesized under these conditions was estimated to be 1.
97 eV and it was characterized as an indirect band gap semiconductor .
The study also acknowledged the existence of six known polymorphs of CuMoO4, including the lowtemperature -CuMoO4 and high-temperature CuMoO4, with the room-temperature triclinic .
being the focus of this A thermal analysis in Figure 8 indicated a phase transition around 570 oC.
These findings highlight that hydrothermal temperature is a crucial parameter for tailoring not only the crystallinity but also potentially the polymorphic phase of CuMoO4.
Different polymorphs can possess distinct electronic structures and surface characteristics, which would directly impact their photocatalytic 2 Co-precipitation Method Direct chemical precipitation is a widely used method for synthesizing inorganic materials, involving the formation of a solid product from a solution phase .
This occurs when precursor solutions containing copper and molybdate ions are mixed, leading to a reaction that yields an insoluble copper molybdate compound.
Coprecipitation refers to the simultaneous precipitation of both copper and molybdate Variations of this method include surfactant-free or surfactant-assisted approaches, with subsequent steps typically involving washing, drying and often calcination to obtain the final material.
CuMoO4 nanoparticles was also prepared through a co-precipitation method as a component for CuMoO4/ZnO nanocomposites .
The precursors used were 3 M CuSO4 and sodium dodecyl sulfate (SDS) as a surfactant, dissolved in deionized water and an aqueous solution of (NH.
6Mo7O24UIH2O.
The molybdate-based solution was added dropwise to the copper-based solution and the mixture was heated to 65 AC for 2 hours.
The greenish precipitate obtained was washed and dried in a vacuum at 60 AC.
The average particle size of these CuMoO4 nanoparticles was reported to be 190 nm and XRD confirmed the CuMoO4 phase (JCPDS: 85-1.
Notably.
FTIR analysis detected the presence of C-C bonds from unwashed SDS on the CuMoO4 material.
The CuMoO4/ZnO demonstrated photocatalytic activity, degrading 92 % of MB and 84 % of RhB under UV irradiation after 70 min.
Pure CuMoO4 synthesized by this coprecipitation method showed 66 % degradation of MB and 59 % degradation of RhB under similar While the ZnO/CuMoO4 system demonstrates the efficacy of co-precipitation in forming effective heterojunctions, the versatility of this synthesis method is further evidenced by its successful application in other composite systems.
For instance, recent studies on Ag-doped CuMoO4 synthesized via co-precipitation have shown that this method allows for the precise incorporation of noble metal dopants into the lattice structure without inducing phase segregation.
The coprecipitation route facilitates a uniform distribution of Ag nanoparticles .
anging from 60120 n.
, which act as electron sinks.
This structural integration, achieved specifically through the controlled supersaturation inherent to co-precipitation, resulted in a MB degradation efficiency of nearly 99 % under visible light, significantly higher than that of pure CuMoO4.
The ability of this method to maintain stoichiometry at low temperatures prevents the agglomeration often seen in solid-state routes, thereby preserving the active surface sites required for dye adsorption .
Furthermore, the co-precipitation technique has proven vital in constructing g-C3N4/CuMoO4 composites, where it addresses the common challenge of poor interfacial contact between the organic nitride nanosheets and the inorganic Unlike physical mixing, in-situ coprecipitation allows CuMoO4 nuclei to grow directly onto the g-C3N4 framework.
This intimate contact, fostered by the gradual precipitation Z-scheme heterojunction that promotes efficient charge Comparative data indicates that such co-precipitated g-C3N4/CuMoO4 hybrids achieve degradation rates for cationic dyes .
ike MB) that 3 to 1.
5 times faster than their physically mixed counterparts .
Thus, the co- Figure 8.
Thermal analysis (TG/DTA) of the CuMoO4 precursor.
The curves indicate weight loss events and heat flow changes, revealing a distinct phase transition and crystallization event occurring at approximately 570 oC.
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 254 precipitation method is not merely a fabrication route but a critical strategy for engineering the interface quality essential for high-performance 3 Thermal-decomposition Method This strategies where thermal decomposition is a key step, either occurring before or after a precipitation event, to yield the final CuMoO4 One approach involves thermally decomposing initial precursors to generate reactive species that subsequently precipitate as CuMoO4 nanoparticles (NP.
, a synthesis route decomposition to precipitation method .
, as Figure Different concentrations from 0.
1 M, 0.
2 M, and 0.
3 M were used, which affected the band gap of the resulting CuMoO4 .
97 eV, 1.
86 eV, and 1.
44 eV.
The 0.
3 M CuMoO4 NPs exhibited superior photocatalytic efficiency for MB degradation, attributed to a low electron-hole recombination rate.
A more commonly encountered route precipitates an intermediate precursor that is then thermally decomposed .
alcined or sintere.
to yield the final CuMoO4 material.
The strategy of precipitating an intermediate followed by thermal decomposition is a prevalent and effective means of producing crystalline CuMoO4-based materials, often allowing for good morphological control .
The thermal decomposition step is crucial for phase formation, enhancement of crystallinity and removal of volatile components from the precipitated precursor .
This twostep approach can offer superior control over the final properties of the synthesized materials, compared to direct high-temperature methods, as the characteristics of the precursor such as size and shape can be tailored first, often influencing the morphology of final product.
The alternative thermal decomposition-precipitation sequence .
is less conventional for molybdates and requires further clarification of its specific mechanism and experimental details.
4 Solid-State High-Temperature Reaction The solid-state reaction typically involves intimately mixing solid precursors .
ften metal oxides or salt.
in stoichiometric proportions, followed by one or more high-temperature calcination or sintering steps .
These elevated temperatures facilitate solid-state diffusion and chemical reaction between the components, leading to the formation of the desired compound.
Polycrystalline -CuMoO4 photocatalysts were synthesized by a conventional solid-state reaction using high-purity CuO and MoO3 as precursors .
These precursors were mixed stoichiometrically and meticulously ground in an agate mortar.
The mixture was then sealed in platinum crucibles and subjected to a first heat treatment at 500 oC for 16 hours.
After this step.
Figure 9.
Schematic workflow of the thermal-decomposition synthesis route for CuMoO4 nanoparticles.
The process involves the initial reaction of molybdate and copper precursors to form an intermediate precipitate, followed by washing, drying and calcination at 500 oC to achieve the final crystalline product .
Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 255 the samples were ground again and then underwent a second heat treatment at 650 oC for 14 hours to ensure homogeneity and complete reaction for -CuMoO4 formation.
Finally, the reaction products were cooled at a rate of 393 K/h to room temperature.
XRD analysis as shown in Figure 10 confirmed the formation of -CuMoO4, which crystallized in the triclinic system with the ycEycE1 space group.
A minor secondary phase of approximately 2 % MoO3 was also detected.
Solid-state synthesis is effective for producing highly crystalline and thermodynamically stable phases of CuMoO4, such as the -CuMoO4.
However, a general characteristic of this method is the production of materials with relatively larger particle sizes and consequently lower specific surface areas compared to those typically obtained via wet-chemical routes .
This can be a disadvantage for photocatalytic applications where a high surface area is often crucial for providing sufficient active sites .
The main advantages of solid-state reactions lie in their simplicity for bulk powder synthesis and their ability to achieve thermodynamic equilibrium phases .
This section reviews a range of synthesis methodologies for CuMoO4-based photocatalysts, encompassing hydrothermal techniques, coprecipitation, thermal decomposition involving precipitation and solid-state high-temperature Each method presents distinct advantages and challenges in terms of controlling crucial physicochemical properties that dictate photocatalytic efficacy.
A notable observation wet-chemical .
recipitation, hydrothermal routes involving precursor formation and methods leading to intermediate compound.
is the frequent and often critical role of post-synthesis calcination or Figure 10.
Observed .
ed dot.
and calculated .
lack lin.
X-ray diffraction patterns from the Rietveld refinement of solid-state synthesized CuMoO4.
The analysis confirms the sample crystallizes in the triclinic system .
pace group P.
with a minor MoO3 impurity phase .
This thermal treatment step is essential for achieving the desired crystalline phase, removing volatile impurities or solvent photocatalytic potential of the CuMoO4 material.
The temperature and duration of calcination are themselves critical parameters influencing the final properties .
The selection of an appropriate synthesis strategy is of importance it directly affects the characteristics of the material and consequently, its performance in the photocatalytic degradation of persistent organic pollutants.
Understanding the relationship between synthesis parameters, post-synthesis treatments and the resultant structural and electronic properties is vital for the rational design and reproducible fabrication of highly efficient CuMoO4-based photocatalysts.
Future research should continue to focus on establishing clearer structure-property-activity relationships that are directly linked to specific and well-documented synthesis protocols of CuMoO4-based materials.
The following Table 2 summarizes the key details from the discussed synthesis methods for CuMoO4-based materials as reported in the provided literature.
Stability.
Recyclability and Practical Application While the initial photocatalytic activity of CuMoO4 is promising, its practical industrial application hinges on long-term stability and A primary concern for copper-based photocatalysts is the potential leaching of Cu2 ions into the treated effluent, which can lead to secondary pollution.
Although CuMoO4 is generally stable at neutral pH, acidic conditions .
H < .
can accelerate the dissolution of the copper sub-lattice .
Most studies evaluate recyclability over 4 to 5 consecutive cycles, typically reporting a minor efficiency loss of < 5%, which is often attributed to the physical loss of catalyst powder during recovery rather than chemical deactivation .
However, rigorous quantification of dissolved copper in the final effluent is frequently omitted in the literature.
Recent work .
highlighted that while Mo-based phases can suffer from leaching, optimizing the synthesis method .
, sol-gel vs.
co-precipitatio.
and incorporating carbonaceous supports .
ike graphene oxide or biocha.
can significantly enhance chemical stability by shielding the active sites from photocorrosion .
Furthermore, a significant gap remains between laboratory results and real-world application.
The vast majority of current research utilizes simulated wastewater containing single model dyes such as MB or RhB in deionized water.
In contrast, real industrial effluents contain complex mixtures of inorganic ions (Cl-.
SO42-.
CO32-), natural organic Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 256 matter and varying pH levels, all of which can act as radical scavengers and deactivate surface active sites.
Future research must prioritize testing in real wastewater matrices and exploring scalable reactor designs, such as immobilized catalyst beds or continuous flow systems, to validate the techno-economic viability of CuMoO4 Conclusion and Outlook Photocatalytic degradation of refractory organics using CuMoO4-based materials has progressed rapidly over the past six years, moving sophisticated, multi-component architectures under visible irradiation.
A comparative analysis Table 2.
Comparative overview of synthesis methodologies for CuMoO4-based materials.
The table lists precursor materials, reaction conditions and resulting morphological properties for hydrothermal, coprecipitation, thermal-decomposition and solid-state routes.
Synthesis Method Specific CuMoO4 Material / Phase Copper Precursor .
Molybdenu m Precursor .
Solvent .
/ Medium Key Reaction Parameters PostSynthesis Treatment Morpholog y / Size Ref.
Conventional Hydrothermal CuMoO4
AeCoMoO4
CuCl2UI2H2O
Na2MoO4UI2
H2O
Distilled water .
180 AC, 12 hours (Coprecursor:
CoCl2UI6H2O, 1 Washed, dried .
AC, 12 h, calcined .
AC, 4 hours.
Sea-urchinlike hollow es with on surface .
TemperatureControlled AuinsituAy Hydrothermal CuMoO4 Optimal: 180 AC, 10 hours.
Disparate lead to .
Direct Chemical Precipitation (SurfactantFre.
CuMoO4
Cupric
[(CH3COO)2C
uAH2O] Sodium [Na2MoO.
Doubledistilled Room Washed .
ater, ethano.
, airdried .
, calcined .
AC, 5 hour.
Rock-like .
Direct Chemical Precipitation (Coprecipitation Surfactan.
CuMoO4 3M CuSO4 (NH.
6Mo7O 24UIH2O .
Deionize d water Heated to 65 AC for 2 hours.
SDS as Dropwise Washed, dried .
acuum, 60
AC)
Average .
ThermalDecomposition CuMoO4 NPs Cu precursor .
1, 0.
2, 0.
ot Details of steps not Nanopartic .
Solid-State HighTemperature Reaction
CuMoO4
CuO (Ou99%) MoO3
(Ou99%) Solid
Mixed, heat: 773 K
AC), 16
Ground.
heat: 923 K
AC), 14
Cooled 393 K/h.
None Polycrystal line powder article size not .
Sonochemical CuMoO4 Cu(NO.
2A6 H2O
(NH.
CIMoCNO 24A4H2O Distilled water .
Ultrasonic .
robe, 20 kHz, 50 W) Filtered, washed with at 60 AC for 1 Spherical es, 50Ae55 Copyright A 2026.
ISSN 1978-2993 Bulletin of Chemical Reaction Engineering & Catalysis, 21 .
, 2026, 257 of > 60 studies reveal that morphology alone typically yields less than a twofold increase in It is recommended that combining shape control with heterojunction formation or defect engineering can boost rate constants and quantum yields by nearly ten times.
Another important finding is that band-structure adjustments via such as creating oxygen vacancies or co-doping with aluminum or phosphorus would narrow the band gap, introduce electron-hole recombination, enhancing sunlight utilization without sacrificing redox power.
Another major finding from this review is the incorporation of plasmonic or single-atom co-catalysts which accelerates interfacial reactions.
This approach however poses cost and stability challenges, from nanoparticle aggregation to copper leaching, which drives the search for lower-cost, more durable alternatives like copper-rich defect phases or carbon-based additives.
To date, hierarchical heterojunctions deliver the best balance of broad light absorption and strong redox capability, achieving over 95 % removal of antibiotics and dyes in 30 to 70 min under natural or simulated sunlight.
Despite these advances, there is an issue posed by the mechanistic precision.
In-situ spectroscopies (EPR.
XPS.
ATR-FTIR) and timeresolved photoluminescence are ideal, coupled with density-functional theory (DFT) to map charge-carrier dynamics, identify true active sites and predict optimal compositional spaces.
Furthermore, bridging the gap between laboratory efficiency and industrial viability will require a shift from simple dye-degradation studies to rigorous pilot-scale evaluations Addressing these combined fundamental and engineering challenges will pave the way for robust, low-cost CuMoO4 photocatalysts capable of broad environmental application and aligning with sustainable-development goals (SDG).
CRedit Author Statement Author Contributions: H.
Abdullah: funding acquisition, investigation and formal analysis.
Jusoh: investigation.
Safie: investigation.
Nasaruddin: formal Khan: investigation.
Arifin:
project administration, & All authors have read and agreed to the published version of the manuscript.
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Acknowledgment