Photoelectrocatalytic Oxidation Research Articles

A chemoenzymatic cascade for sustainable production of chiral N-arylated aspartic acids from furfural and waste

Both biomass valorization and waste upcycling are important routes to sustain the circular bioeconomy. In this work, we present a chemoenzymatic cascade for selective synthesis of chiral N-arylated aspartic acids from biomass-derived furfural and waste nitrophenols (NPs) by merging robust photo- and electrocatalysis with stereoselective biocatalysis. Concurrent photoelectrocatalytic oxidation of furfural into maleic acid (MA) and fumaric acid (FA) was significantly enhanced by combining catalyst and reaction engineering strategies including identification of a powerful photocatalyst meso-tetra(4-carboxyphenyl)porphyrin, continuous flow technique, enhancing dissolved O2 and paired electrosynthesis. The overall space-time yield (STY) approached 2.8 g L−1 h−1 in a fed-batch process, with the product titer of 28.3 g L−1. Besides, photoelectrosynthesis of MA/FA was effectively fueled by sunlight, with the STY of up to 3.6 g L−1 h−1. Both MA selectivity and yield could be facilely improved to around 89% by reducing the buffer concentrations. Paired electrosynthesis strategy not only resulted in greatly improved MA production at the anode, but also enabled NPs upcycling into value-added aminophenols (APs) at the cathode. The products formed in the two electrode chambers were converted into N-arylated (S)-aspartic acids by a bienzymatic cascade. This work presents a multicatalytic approach for integrating selective biomass valorization and waste upcycling towards sustainable manufacture.

Ti-O-Cu Nanotubular Mixed Oxide Grown on a TiCu Alloy as an Efficient Material for Simultaneous Photoelectrocatalytic Oxidation and PMS Activation for Pollutant Degradation.

This study introduces a novel photoelectrocatalytic (PEC) system featuring a Ti-O-Cu mixed nanotubular oxide photoanode for the simultaneous activation of peroxymonosulfate (PMS), targeting the removal of emerging contaminants, such as methylene blue dye, tetracycline, and ibuprofen. The Ti-5.5Cu (atom %) alloy substrate and the nanotubular oxide layer were synthesized through arc melting and electrochemical anodization. The conditions of photoelectrocatalysis-assisted PMS activation (PEC/aPMS) were optimized using experimental design, achieving 90.4% decolorization of methylene blue dye within 30 min under optimal conditions: pH 4, an applied potential of 0.5 V vs Ag/AgCl, and a PMS concentration 50 times the molar concentration of the contaminant, utilizing a 10 W UV LED at 365 nm. In contrast, only 25% decolorization was observed without PMS. Singlet oxygen (1O2) was identified as the primary pathway for PMS activation (nonradical). Additionally, the PEC/aPMS system effectively degraded model contaminants, achieving 52% degradation of ibuprofen, 78% of methylene blue, and 92% of tetracycline in 10 mg L-1 total organic carbon solutions within 60 min under optimized conditions. The electrode exhibited remarkable stability, maintaining its efficiency throughout the experiments. These findings highlight the potential of mixed nanostructured oxide electrodes for developing highly efficient and durable PEC systems with integrated PMS activation for the removal of organic contaminants.

Development of engineered Zn-MOF/g-C3N4 based photoelectrochemical system for real-time sensors and removal of naproxen in wastewater

Naproxen-contaminated water may lead to the accumulation of the drug in aquatic organisms and can pose high risks to an aquatic environment and human beings. Therefore, this work aimed to develop photoelectrochemical sensing and degradation of naproxen (NPX) using zinc-metal organic framework /graphitic carbon nitride thin film-based fluorine-doped tin oxide (Zn-MOF/g-C3N4/FTO) as anode material for the sensing and degradation of naproxen (NPX). The surface morphology, structure, surface property, surface area, optical property, photocurrent, and charge transfer kinetics abilities were studied using different techniques. The nanocomposites showed a superior photocurrent response (0.815 mA cm-2) compared to the original g-C3N4 (0.328 mA cm-2). The photo-anode made of Zn-MOF@g-C3N4/FTO displayed the highest photocurrent value, indicating that the alignment of the two semiconductor bands prevented the quick recombination of electron-hole pairs. Owing to these attractive features, the Zn-MOF/g-C3N4/FTO electrode was applied for photoelectrochemical detection of NPX using chronoamperometry. Interestingly, the nanocomposites-based FTO ascribed a lower detection limit (2.3 ng l-1) with a wide linear range concentration of NPX (0.5 to 200 µg l-1). Additionally, the analytical assessment of repeatability and reproducibility demonstrated robust performance, with commendable relative standard deviations (RSD%) of 2.54 % and 2.40 %, respectively. On the other hand, a remarkable degradation efficiency of 97.52 % was attained when employing a bias potential of 0.1 V during a 2 h photoelectrocatalytic oxidation of NPX. The degradation process was primarily driven by the active participation of holes and hydroxyl radicals in ring opening and subsequent cleavage of by-products. The notable effectiveness of this degradation can be attributed to the combined and synergistic effects of both electrochemical and photocatalytic degradation techniques. The current state demonstrates its effectiveness in the photoelectrochemical sensing and removal of NPX using MOF/g-C3N4 nanocomposites-based electrode materials in wastewater.

Advancing nanoarchitectures of 2D WO3/MXene photoanode for enhanced photoelectrocatalytic oxidation of phenol and arsenic in synthetic wastewater

The photoelectrocatalytic advanced oxidation process (PEAOP) necessitates high-performing and stable photoanodes for the effective oxidation of complex pollutants in industrial wastewater. This study presents the construction of 2D WO3/MXene heteronanostructures for the development of efficient and stable photoanode. The WO3/MXene heterostructure features well-ordered WO3 photoactive sites anchored on micron-sized MXene sheets, providing an increased visible light active catalytic surface area and enhanced electrocatalytic activities for pollutant oxidation. Phenol, a highly toxic compound, was completely oxidized at an applied potential of 0.8 V vs. RHE under visible light irradiation. Systematic optimization of operational conditions for the photoelectrocatalytic oxidation of phenol was conducted. The phenol oxidation mechanism was elucidated via high-performance liquid chromatography (HPLC) analysis and the identification of intermediate compounds. Additionally, a mixed model of phenol and arsenic (III) in polluted water demonstrated the capability of WO3/MXene photoanode for the simultaneous oxidation of both organic and inorganic pollutants, achieving complete conversion of phenol and As(III) to non-toxic As(V). The WO3/MXene photoanode facilitated water oxidation, generating a substantial amount of O2•– and •OH oxidative species, which are crucial for the concurrent oxidation of phenol and arsenic. Recyclability tests demonstrated a 99% retention of performance, confirming the WO3/MXene photoanode's suitability for long-term operation in PEAOPs. The findings suggest that integrating WO3/MXene photoanodes into water purification systems can enhance economic feasibility, reduce energy consumption, and improve efficiency. This PEAOP offers a viable solution to the critical issue of heavy metal and organic chemical pollution in various water bodies, given its scalability and ability to preserve ecosystems while conserving clean water resources.

Partial Photoelectrocatalytic Oxidation of 3‐Methylpiridine in Green Conditions by Nanotube/Nanowire Ti/TiO2 Plates Prepared in Aqueous, Glycerol, or Ethylene Glycol Medium

AbstractNanotube/nanowire structured TiO2 samples on Ti plates were prepared by anodic oxidation in aqueous, glycerol or ethylene glycol medium under different experimental conditions and characterized by XRD, SEM‐EDX, electrochemical methods (photocurrent profiles and electrochemical impedance spectroscopy). The nanostructured TiO2 was built on relatively large Ti plates, and consequently, in some preparation conditions, different morphologic properties were observed in the underside and upside zones of the electrodes, especially in ethylene glycol medium. The electrodes were tested for selective photoelectrocatalytic oxidation of 3‐methylpyridine to 3‐pyridinemethanol, 3‐pyridinemethanal and vitamin B3 in water under UVA irradiation. The best performance was found with the electrode prepared in ethylene glycol/water/NH4F (98/2/0.3 w/w) medium at 36 V potential for 3 h, while the worst was that prepared in aqueous medium which showed the shortest nanostructure length. Unlike photoelectrocatalysis and photocatalysis, no aromatic alcohol/carbonyl products were obtained in electrocatalytic and photolytic experiments. The selectivity values of the products were similar for the various electrodes, while the morphology of the nanotubes/nanowires and their quantity which affects the total active surface area were essential for the substrate conversion. The results also show that the photocurrent intensity, XRD peak intensity, and electrical conductivity are correlated with photoelectrocatalytic activity of the Ti/TiO2 electrodes.

Recent Developments in Nickel-Based Layered Double Hydroxides for Photo(-/)electrocatalytic Water Oxidation.

Layered double hydroxides (LDHs), especially those containing nickel (Ni), are increasingly recognized for their potential in photo(-/)electrocatalytic water oxidation due to the abundant availability of Ni, their corrosion resistance, and their minimal toxicity. This review provides a comprehensive examination of Ni-based LDHs in electrocatalytic (EC), photocatalytic (PC), and photoelectrocatalytic (PEC) water oxidation processes. The review delves into the operational principles, highlighting similarities and distinctions as well as the benefits and limitations associated with each method of water oxidation. It includes a detailed discussion on the synthesis of monolayer, ultrathin, and bulk Ni-based LDHs, focusing on the merits and drawbacks inherent to each synthesis approach. Regarding the EC oxygen evolution reaction (OER), strategies to improve catalytic performance and insights into the structural evolution of Ni-based LDHs during the electrocatalytic process are summarized. Furthermore, the review extensively covers the advancements in Ni-based LDHs for PEC OER, including an analysis of semiconductors paired with Ni-based LDHs to form photoanodes, with a focus on their enhanced activity, stability, and underlying mechanisms facilitated by LDHs. The review concludes by addressing the challenges and prospects in the development of innovative Ni-based LDH catalysts for practical applications. The comprehensive insights provided in this paper will not only stimulate further research but also engage the scientific community, thus driving the field of photo(-/)electrocatalytic water oxidation forward.

Doping of photoactive TiO2 films by DC plasma electrolytic oxidation: Effect of transition metals

Several beneficial features maintain TiO2 in the top list of viable materials for photocatalytic purposes. However, its relatively large band-gap (3.0–3.2 eV) still hampers practical applications under sunlight. This work explores Direct Current (DC) Plasma Electrolytic Oxidation (PEO) of titanium as a fast, easily-scalable and single-step tool to synthesise doped TiO2 photoanodes with controlled morphology, crystalline structure and thickness. Zn-, Cu- and Fe-doped crystalline TiO2 films were obtained in H2SO4 aqueous solutions containing ZnSO4, CuSO4 and FeSO4 precursors, respectively. As-prepared TiO2 films showed a porous and homogeneous sponge-like surface morphology, typical of PEO-produced oxides, and a crystalline phase structure consisting of a mixture of anatase and rutile phases. The anatase content varied in the 54–100 % range and correspondingly the band-gap energy was in the 2.85–3.07 eV range. Doped oxides prepared with a low concentration of the metal precursors showed monochromatic incident-photon-to-current-efficiency (IPCE) values exceeding those obtained with pristine TiO2 by up to 24 %, best performing in the order Zn- > Cu- > Fe-doped TiO2. Photocurrent under polychromatic UV-Vis irradiation showed an analogous trend and the estimated efficiency of solar-light harvesting was in the 0.3–4 % range, with Zn- ≈ Cu- > Fe-doped TiO2. Although the superior performance of the PEO-prepared metal-doped TiO2 could not be fully confirmed by photoelectrocatalytic oxidation tests of organics, the present investigation showed the viability of DC PEO for the synthesis of metal-doped TiO2 photoanodes.

Fabrication of mesoporous titania films and kinetics of photoelectrocatalytic degradation of organic dye

Mesoporous titania films with worm-like patterns were fabricated on indium-tin oxide (ITO) glass by dip-coating skill, and were characterized systematically. Impacts of the process and technical parameters on the formation of the films were investigated. The mesoporous films were characterized by low-angle X-ray diffraction (XRD) and wide-angle XRD, transmission electron microscopy (TEM), scanning electron microscope (SEM), linear sweep voltammograms and nitrogen adsorption/desorption isotherms. Subsequently, the films were used in a photoelectrocatalytic system for the degradation of methyl orange. The influence of operation variables, including pH values, bias potential, light intensity, organics concentration and the mass of the films, on the degradation of the dye was investigated in details. More than 96 % degradation of the organics was achieved in 2 h. The kinetic results for the photoelectrocatalytic oxidation of the organic were also presented in this paper.

Constructing efficient Ti4O7/PbO2 heterostructured photoelectrode for water remediation

Photoelectrocatalytic oxidation (PEC) technology is considered to be an efficient process for the treatment of organic wastewater, and its performance depends on the characteristics of the PEC photoanodes. Therefore, the construction of heterogeneous nanostructured photoelectrodes based on suitable semiconductor materials for fast induced carrier transfer efficiency is essential for a high-performance PEC technique. Herein, titanium suboxide/lead (IV) oxide (Ti4O7/PbO2) ceramic photoelectrode with efficient PEC performance was synthesized by coupling PbO2 nanospheres with Ti4O7 through a hydrothermal method. To maximize the PEC performance of the ceramic electrodes, the Ti4O7/PbO2 nano-heterostructures were optimized by modulating the hydrothermal temperature. The optimized ceramic electrodes possessed a low Tafel slope, a low charge-transfer resistance and a good photocurrent response. Ti4O7/PbO2-110 exhibited an efficient PEC activity (approximately 92.21%) for the degradation of reactive brilliant blue KN-R. The efficient PEC performance of Ti4O7/PbO2-110 arose from the formation of a type II heterojunction between Ti4O7 and PbO2, which achieved efficient photogenerated carrier separation and facilitated the formation of intermediate active species. This work not only validates the efficient performance of Ti4O7/PbO2-110 for PEC water purification but also provides a reference strategy for the preparation of heterostructured ceramic photoelectrodes with a high PEC efficiency.

Enhancing nitrogen removal from wastewater via photoelectrocatalytic oxidation over a Ru/TiO2 system

Water pollution is a significant global environmental concern that threatens the sustainable progress of humanity. In this study, the concepts of photocatalytic oxidation in the cathodic zone (NH4+-N adsorption-NH3-N conversion) and electrochemical oxidation in the anodic zone (NH4+-N direct oxidation + chlorination) were proposed to remove ammoniacal nitrogen, and experimental studies were conducted. The stirring of the test solution during the reaction process enhanced the ammoniacal nitrogen removal efficiency by ∼9% after 90 min of reaction. The removal efficiency of ammoniacal nitrogen was comparatively high at low concentrations. After 60 min of reaction in the presence of 15 mg·L−1 ammonium chloride, the removal efficiency exceeded 95%; the removal efficiency of ionized ammonia increased with increasing current density. After 60 min, the removal efficiency of ammoniacal nitrogen exceeded 80%. Under the same ammoniacal nitrogen concentration conditions, the ammoniacal nitrogen removal efficiency in the test solution increased with the increase in the chlorine ion concentration, and in the absence of chlorine ions, ammoniacal nitrogen removal in the electrochemical reaction environment was insignificant. Under the same power and light conditions, the photoelectrochemical reaction exhibited a ∼15% higher ammoniacal nitrogen removal efficiency than electrochemical oxidation.

Precise Lattice‐Strain Modulation of Hematite Enabled by Gradient Doping of Mn for Enhanced Photoelectrocatalytic Oxidative C─C Bond Scission

The high‐value utilization of biomass feedstock is fascinating but limited by efficient C─H activation to break C─C bonds. Herein, F‐Fe2O3‐Mn photoanodes with modulable compressive strain are fabricated by gradient infusion of Mn into F‐doped hematite (F‐Fe2O3), which is illustrated to be highly efficient for oxidative C─C bond cleavage of various bio‐based 1,2‐diols to produce benzoic acids or aromatic ketones (94.5–97.2% yields) in photoelectrocatalytic (PEC) device, coupling with a high H2 production of 1180 μmol cm−2 (≈96% yield). The gradient doping of Mn species into the photoelectrode bulk results in improved photoexcited carriers separation and transfer efficiency of the photoelectrode (3.41 mA cm−2). On the other hand, the lattice distortion induced by Mn doping also leads to a strain effect on F─Fe2O3─Mn, which can precisely modulate the photoelectrode electronic structure. Control experiments, in situ characterization, and theoretical calculations elaborate that compressive strain is capable of adjusting the position of the d‐band center to facilitate C─H activation, remarkably enabling PEC oxidative C─C bond breaking of 1,2‐diol and the desorption of the oxidized product. This “one‐stone‐two‐bird” strategy presents a straightforward protocol for efficiently breaking C─C bonds in organic and biomass transformations via PEC oxidation.

Research progress on photocatalytic, electrocatalytic and photoelectrocatalytic selective oxidation of 5-hydroxymethylfurfural

This paper summarizes the latest research progress in selective photocatalytic, electrocatalytic, and photoelectrocatalytic oxidation of HMF, along with the reaction mechanisms, advantages, and challenges faced during selective HMF oxidation.

Highly efficient photoelectrocatalytic oxidation of arsenic(iii) with a polyoxometalate-thiacalix[4]arene-based metal–organic complex-modified bismuth vanadate photoanode

A new polyoxometalate-thiacalix[4]arene-based metal–organic photoelectrocatalyst is designed, and then applied to BiVO4 surface modification for enhanced photoelectrocatalytic oxidation of arsenic(iii) under simulated sunlight conditions.

Photoelectrocatalytic chemical oxygen demand analysis using a TiO2 nanotube array photoanode

The chemical oxygen demand (COD) is a widely used parameter to evaluate the quality of water for industrial applications. Currently, the standardized method for COD analysis employs expensive and harmful reagents that require a special treatment for disposal upon use. The photoelectrocatalytic COD detection, based on the photocatalytic activity of a reduced TiO2 nanotube array photoanode (Ti|NT-TiO2) under supply of a low bias potential, represents a fast, cheap and eco-friendly alternative to the standard COD method (CODSTD). Here, Ti|NT-TiO2 was synthesized by the anodization method followed by heat treatment and electrochemical reduction. Potassium hydrogen phthalate, glucose and acetic acid were used as model organic compounds. The photoelectrocatalytic detection of COD (CODPEC) is based on the photoelectrocatalytic oxidation of target compounds on the surface of the reduced Ti|NT-TiO2 under UV illumination. Photocurrent transients were recorded using chronocoulometry, and the net charge (Δq) was plotted as a function of the theoretical COD (CODTH). A linear relationship was found between these two parameters regardless of the model compound. That relationship was used to determine the CODPEC for acetylsalicylic acid and Terasil Blue dye solutions at concentrations within the range of 0–15 mg L−1. A good agreement between CODPEC and CODSTD was achieved. The limit of detection of the method was 3.6 mg L−1 COD, with the linear range established from 0 to 50 mg L−1.

Bench-scale photoelectrocatalytic reactor utilizing rGO-TiO2 photoanodes for the degradation of contaminants of emerging concern in water

Pharmaceuticals and personal care products are contaminants of emerging concern (CEC) in water. Photocatalysis (PC) and photoelectrocatalysis (PEC) are potential advanced oxidation processes for the effective degradation of these contaminants. In this work a bench-scale photoelectrocatalytic reactor utilizing a UVA-LED array was designed and tested for the degradation of diclofenac as a model CEC. Reduced graphene oxide-titanium dioxide (rGO-TiO2) composite, prepared by the photocatalytic reduction of rGO on TiO2, was immobilised on fluorine doped tin oxide (FTO) glass and evaluated as a photoanode. The influence of UVA intensity and rGO:TiO2 ratio on the degradation rate was studied. Surface modification of the TiO2 with 1% rGO gave the highest photocurrent and best degradation rate of diclofenac, as compared to unmodified TiO2. However, following repeat cycles of photoelectrocatalytic treatment there was an observed drop in the photocurrent with rGO-TiO2 anodes and the rate of diclofenac degradation decreased. Raman and XPS analysis indicated the re-oxidation of the rGO. Attempts to regenerate the rGO in-situ by electrochemical reduction did not prove successful, suggesting that the site of photoelectrocatalytic oxidation of rGO was different to the reduction site targeted in the photocatalytic reduction for the formation of the rGO-TiO2 composites.

Sustainable application of electrocatalytic and photo-electrocatalytic oxidation systems for water and wastewater treatment: a review.

Wastewater treatment and reuse have risen as a solution to the water crisis plaguing the world. Global warming-induced climate change, population explosion and fast depletion of groundwater resources are going to exacerbate the present global water problems for the forthcoming future. In this scenario, advanced electrochemical oxidation process (EAOP) utilising electrocatalytic (EC) and photoelectrocatalytic (PEC) technologies have caught hold of the interest of the scientific community. The interest stems from the global water management plans to scale down centralised water and wastewater treatment systems to decentralised and semicentralised treatment systems for better usage efficiency and less resource wastage. In an age of rising water pollution caused by contaminants of emerging concern (CECs), EC and PEC systems were found to be capable of optimal mineralisation of these pollutants rendering them environmentally benign. The present review treads into the conventional electrochemical treatment systems to identify their drawbacks and analyses the scope of the EC and PEC to mitigate them. Probable electrode materials, potential catalysts and optimal operational conditions for such applications were also examined. The review also discusses the possible retrospective application of EC and PEC as point-of-use and point-of-entry treatment systems during the transition from conventional centralised systems to decentralised and semi-centralised water and wastewater treatment systems.

Photoelectro-catalytic oxidation of monoethanolamine: From the study of electrooxidation mechanism to the development of high-efficient Ni-based photoelectro-catalysts

Monoethanolamine (MEA) electrooxidation occurring on Ni catalyst has proven to be a viable tactics for simultaneous MEA degradation and energy recovery. However, the excessively large overpotential (1505 mV) on Ni catalyst either causes high electricity consumption when acquiring H2 from MEA-containing electrolyzer or leads to low energy output when extracting electricity from direct MEA fuel cell. In this context, the reaction mechanism of MEA electrooxidation on Ni-based catalyst is deciphered at first by employing a specially designed three-step electrochemical procedure and in-situ Raman spectroscopy. Electrochemical data deconvolutions indicate the indirect electrochemical-chemical reaction path, via Ni(OH)2/NiOOH mediator, occupies ∼2.5 % of the total catalytic current density at 0.55 V vs. Ag/AgCl and the direct oxidation of MEA ranks the rest ∼97.5 %. To decrease the onset potential of MEA oxidation, a photoelectric-catalytic system including high-efficient Ni-based photoelectric-catalyst, where Ni is intimately coated on TiO2 by in-situ photodeposition to achieve the shortest carrier transport channel between Ni(OH)2 and TiO2, is developed. Results show the overpotential of MEA electrooxidation under illumination significantly drops to 255 mV. Such a Ni@TiO2/FTO electrode also exerts excellent durability toward MEA oxidation.

Sn-Doped Hematite Films as Photoanodes for Photoelectrochemical Alcohol Oxidation

Here, the modification of semiconductor thin film hematite photoanode by doping with Sn ions is reported. Undoped and Sn-doped hematite films are fabricated by the electrochemical deposition of FeOOH from aqueous alkaline electrolyte, followed by calcination in air. The photoanodes were tested in photoelectrocatalytic oxidation of water, methanol, ethylene glycol, and glycerol. It is shown that modification by tin dramatically increased the activity of hematite in the photoelectrochemical oxidation of alcohols upon visible light irradiation. The photoelectrocatalytic activity of Sn-modified hematite increased in the sequence of: H2O < MeOH < C2H2(OH)2 < C3H5(OH)3. The quantum yield of photocurrent in the oxidation of alcohols reached 10%. The relatively low photocurrent yield was ascribed to the recombination of photoexcited holes within the hematite layer and on surface states located at the hematite/electrolyte interface. Intensity-modulated photocurrent spectroscopy (IMPS) was used to quantify the recombination losses of holes via surface states. The IMPS results suggested that the hole acceptor in the electrolyte (alcohol) influences photocurrent both by changing the charge transfer rate in the photoelectrooxidation process and by the efficient suppression of the surface recombination of generated holes. Thin-film Sn-modified hematite photoanodes are promising instruments for the photoelectrochemical degradation of organic pollutants.

WO3/Bi2WO6 photoanode enhancement for photoelectrocatalytic water oxidation; scan rate effect optimization in the cyclic voltammetry deposition method

The photoelectrocatalytic approach is a very efficient technology for eliminating microorganisms and organic contaminants. The development of photoanode is widely recognized as a crucial approach to enhancing the efficiency of photoelectrocatalytic cells. The key goal of this methodology is to enhance the efficacy of photoelectrocatalytic oxidation by optimizing composited photoanode fabrication. This research development focuses mainly on fabricating composite WO3/Bi2WO6 semiconductor thin films with high water oxidation efficiency and favorable photoelectrocatalytic E. coli degradation applications. Cyclic voltammetry was utilized to create WO3/Bi2WO6 thin coatings on conducting glass while optimizing the photoelectrocatalytic activity via the scan rate parameter. The characteristics of the developed electrode, including charge transfer resistance, optical properties, morphology, crystal structure, chemical composition, and oxidation numbers, were investigated to improve photoelectrocatalytic activity. It was observed that the scanning rate significantly influenced the characteristics of the WO3/Bi2WO6 electrode and the photoelectrocatalytic activity on water oxidation. It was discovered that the WO3/Bi2WO6 electrode prepared with a scan rate of 25 mV/s exhibited the greatest photoelectrocatalytic water oxidation as well as distinguishing characteristics from other conditions. The decision to utilize decreased scanning rates has been determined to optimize the reaction kinetics and improve the film-forming properties of WO3/Bi2WO6. Significantly, the developed electrode can also be used to eliminate 87.5% of E.coli in 15 minutes via a photoelectrocatalytic catalytic mechanism. The photoanode composed of WO3/Bi2WO6 has promising capabilities in removing microorganisms and organic pollutants, making it a viable candidate for future advancements in wastewater management applications.

WO3‐based Materials for Photocatalytic and Photoelectrocatalytic Selective Oxidation Reactions

AbstractSelective oxidation reactions are crucial in producing various chemicals in the industry. However, most catalytic processes for these reactions use harsh reaction conditions. Recently, heterogeneous photo(electro)catalysis has been considered promising for selective oxidation reactions under mild conditions. Semiconductor materials are frequently used as heterogeneous photocatalysts because they can produce active species that contribute to the oxidation of organic compounds under light irradiation. Among various semiconductor photocatalysts, tungsten oxide (WO3) is one of the most promising candidates due to its advantages, including high stability, wide light adsorption range, proper band structures, and unique catalytic mechanism. This paper reviews the WO3‐based materials for photocatalytic (PC) and photoelectrocatalytic (PEC) selective oxidations. We summarize the strategies for designing WO3 structures, which include morphology control, crystal facet optimization, and defect engineering. Then, the finely designed WO3 structures for PC and PEC oxidation of several typical organic compounds have been discussed based on catalytic mechanism and performance. Finally, we propose the prospects and challenges of WO3 photocatalysts and photoanodes in selective oxidation reactions.