Electrochemical Oxidation Technique Research Articles

Study on the efficient electrocatalytic depolymerization of α-O-4 bond in lignin assisted by simple electrolyte

Lignin is anticipated to serve as a replacement for dwindling fossil fuel resources owing to its abundant sources and renewable nature. The electrochemical oxidation technique for depolymerizing lignin has garnered significant interest for its environmentally friendly and mild operating conditions. Nevertheless, the current utilization of auxiliary electrolytes, predominantly organic bases, ionic liquids, and other specialized substances, poses a constraint on the widespread adoption of this approach. Furthermore, there is a scarcity of instances where electrochemical technology has been employed to depolymerize the α-O-4 bond in lignin for the production of highly selective acetals. In this study, a sodium chloride/methanol (NaCl/MeOH) system was utilized for the direct depolymerization of the α-O-4 bond in a lignin model molecule, specifically benzyl phenyl ether (BPE). The optimal conditions resulted in a 95.2 % conversion rate of the BPE substrate and a high yield of 94.5 % for the main product, benzaldehyde dimethyl acetal(Bda). This research offers a promising approach for the electrocatalytic depolymerization of α-O-4 bonds in lignin, leading to the selective production of acetal chemicals using a common auxiliary electrolyte at room temperature in just 2 h.

Research Progress of Chromophoric Dissolved Organic Matter (CDOM) in Landfill Leachate by Electrochemical Method

Over the years, industry, agriculture and other human activities have discharged large amounts of organic pollutants into landfills. Among them, color-resistant dissolved organic pollutants have attracted great attention. In order to achieve the safe discharge of wastewater, a variety of treatment technologies have been used to effectively eliminate CDOM in water. In this paper, the most promising electrochemical oxidation (EO) techniques are reviewed, their basic principles are introduced, and the research progress and application status of electrode materials and electrochemical reactors are introduced. At the same time, the substance composition and detection method of CDOM are discussed. Finally, the performance of EO technology to remove CDOM is summarized. However, we should note that electrode optimization has always been the core of EO technology improvement, and the combination of updated electrode material iteration and treatment process has broad prospects for the wide application of EO technology.

A simple strategy towards construction of copper foam-based robust superhydrophobic coating based on perpendicular nanopins for long-lasting delayed icing and reduced frosting

Icing/frosting poses a significant problem for materials used in everyday applications. In recent years, anti-icing methods utilizing superhydrophobic materials have become popular. These materials have superhydrophobic surfaces with air-solid composite structures, which can prevent icing/frosting by creating air cushions in the micro- and nano-scales of the rough structure. However, long-term protection of the substrate is challenging due to air leakage from the air cushion and the breakdown of the superhydrophobic coating. The use of superhydrophobic materials in cold environments is also greatly limited by this shortcoming. In this paper, superhydrophobic copper foam (SHS CF) was created by using electrochemical oxidation and impregnation techniques and subsequent modified by fluorosilane coupling agent on the copper foam surface to reduce surface particle activity through condensation reactions, achieving a superhydrophobicity with a water contact angle of up to 170±2°. Furthermore, gas was utilized to form a specific rough structure by combining with Cu(OH)2 micro-nanopins, leading to the development of long-lasting gas in SHS CF (LAG-SHS CF). The LAG-SHS CF exhibited impressive anti-frost characteristics, with a delayed icing time of approximately 2171 s. Notably, the SHS CF retained strong wetting capabilities and excellent resistance to abrasion, UV, acid, and alkali even after the removal of LAG, which was ascribed to the fact that the composite structure effectively reduces the solid-liquid contact area and has a high roughness. These properties provide a solid foundation for the application of LAG-SHS CF. The findings of this study contribute to the creation of new materials with anti-icing and anti-frost properties.

Integrated Electrochemical Oxidation and Biodegradation for Remediation of a Neonicotinoid Insecticide Pollutant.

A novel integrated electrochemical oxidation (EO) and bacterial degradation (BD) technique was employed for the remediation of the chloropyridinyl and chlorothiazolyl classes of neonicotinoid (NEO) insecticides in the environment. Imidacloprid (IM), clothianidin (CL), acetamiprid (AC), and thiamethoxam (TH) were chosen as the target NEOs. Pseudomonas oleovorans SA2, identified through 16S rRNA gene analysis, exhibited the potential for BD. In EO, for the selected NEOs, the total percentage of chemical oxygen demand (COD) was noted in a range of 58-69%, respectively. Subsequently, in the biodegradation of EO-treated NEOs (BEO) phase, a higher percentage (80%) of total organic carbon removal was achieved. The optimum concentration of NEOs was found to be 200 ppm (62%) for EO, while for BEO, the COD efficiency was increased up to 79%. Fourier-transform infrared spectroscopy confirms that the heterocyclic group and aromatic ring were degraded in the EO and further utilized by SA2. Gas chromatography-mass spectroscopy indicated up to 96% degradation of IM and other NEOs in BD (BEO) compared to that of EO (73%). New intermediate molecules such as silanediamine, 1,1-dimethyl-n,n'-diphenyl produced during the EO process served as carbon sources for bacterial growth and further mineralized. As a result, BEO enhanced the removal of NEOs with a higher efficiency of COD and a lower consumption of energy. The removal efficiency of the NEOs by the integrated approach was achieved in the order of AC > CL > IM > TH. This synergistic EO and BD approach holds promise for the efficient detoxification of NEOs from polluted environments.

Development of Ti4O7 reactive electrochemical membrane and electrochemical oxidation of naphthols in aqueous solution

Naphthols (NAPs), commonly used phenolic compounds, have significant impact on environmental risk and human health, necessitating advanced treatment methods for their degradation. In this study, a Ti4O7 reactive electrochemical membrane (REM) was developed for the electrochemical oxidation of NAPs. The Ti4O7 REM presented a porosity of 42.18 ± 2.3% and a median pore diameter of 1.21 µm. High permeability (846 LMH bar−1) was achieved at relatively low transmembrane pressure and resulted in a convection-enhanced rate constant for Fe (CN)64- oxidation of 1.7 × 10−4 m/s. The increase in current density and decrease in plate spacing had a positive influence on NAPs degradation. The TOC removal efficiencies of 1-naphthol (1-NAP) and 2-naphthol (2-NAP) were 68.6% and 63.5%, respectively at the current density of 6 mA/cm2 and plate spacing of 10 mm. Additionally, quantum chemical calculation using density functional theory (DFT) was employed to identify the active sites of NAPs through atom charge and frontier electron density (FED) calculations. Results showed that C14 and C10 were identified as the active sites for 1-NAP, while C9 and C13 were the active sites for 2-NAP. Hydroxyl radical and sulfate radical produced on the electrode surface were the main oxidants for NAPs degradation during the electro-oxidation process. The degradation pathway included hydroxylation, oxygenation, decarbonylation, and ring-open processes, which was in agreement with the theoretical calculations. Furthermore, the quantitative structure-activity relationship (QSAR) predictive model was used to assess the toxicity changes during the electrochemical oxidation process of NAPs, suggesting that the toxicity of intermediates increased at the beginning and significantly reduced at the end. This comprehensive study provides practical and theoretical insights into the application of electrochemical oxidation technique for the reduction of refractory compounds in wastewater.

An integrated approach for the assessment of the electrochemical oxidation of diclofenac: By-product identification, microbiological and eco-genotoxicological evaluation

Diclofenac (DCF), a contaminant of emerging concern, is a non-steroidal anti-inflammatory drug widely detected in water bodies, which demonstrated harmful acute and chronic toxicity toward algae, zooplankton and aquatic invertebrates, therefore its removal from impacted water is necessary. DCF is recalcitrant toward traditional treatment technologies, thus, innovative approaches are required. Among them, electrochemical oxidation (EO) has shown promising results. In this research, an innovative multidisciplinary approach is proposed to assess the electrochemical oxidation (EO) of diclofenac from wastewater by integrating the investigations on the removal efficiency and by-product identification with the disinfection capacity and the assessment of the effect on environmental geno-toxicity of by-products generated through the oxidation.The electrochemical treatment successfully degraded DCF by achieving >98 % removal efficiency, operating with NaCl 0.02 M at 50 A m−2. By-product identification analyses showed the formation of five DCF parental compounds generated by decarboxylic and CN cleavage reactions.The disinfection capacity of the EO technique was evaluated by carrying out microbiological tests on pathogens generally found in aquatic environments, including two rod-shaped Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli), one rod-shaped Gram-positive bacterium (Bacillus atrophaeus), and one Gram-positive coccus (Enterococcus hirae).Eco-toxicity was evaluated in freshwater organisms (algae, rotifers and crustaceans) belonging to two trophic levels through acute and chronic tests. Genotoxicity tests were carried out by Comet assay, and relative expression levels of catalase, manganese and copper superoxide dismutase genes in crustaceans. Results highlight the effectiveness of EO for the degradation of diclofenac and the inactivation of pathogens; however, the downstream mixture results in being harmful to the aquatic ecosystem.

Characterization and mechanism of p-nitrophenol removal based on modified nanoscale zero-valent iron electrocoagulation

p-Nitrophenol (PNP) is a toxic chemical and is difficult to degrade naturally when it enters the environment. It is of great importance to develop methods to remove PNP efficiently and safely. Electrocoagulation has been widely used for the removal of PNP, but challenges remain in the improvement of anode materials and solid-liquid separation of PNP-containing precipitates. In this work, the characteristics and mechanism of activated biochar (ABC) and sulfide dual-modified nanoscale zero-valent iron (nZVI) electrocoagulation anode for the removal of PNP were systematically investigated. The synergistic effect of magnetic iron oxide generated by zero-valent iron oxidation and electrochemical oxidation technique was used to rapidly reduce the PNP concentration for water purification. The results showed that the modified nZVI anode had higher electrocoagulation activity than the iron sheet anode, and the S-nZNI/ABC anode had the highest PNP removal efficiency. The main component of the precipitate after the reaction was Fe3O4, which facilitated the magnetic solid-liquid separation of the precipitate and scum. The seed germination test confirmed that the electrocoagulation material synthesized in this work had almost no adverse effects on the ecological environment. The electrocoagulation process had good degradation performance for PNP, which could significantly attenuate the ecotoxicity of PNP in the aquatic environment and thus improve the water quality. It is expected that this work may provide design references and ideas for the efficient degradation of PNP and the application of electrocoagulation.

Wet removal of elemental mercury by acid-assisted electrochemical oxidation method

As a global pollutant, mercury emission is increasingly restricted in recent years. It is urgent to explore a new and efficient mercury removal technology for coal-fired power plants. A new acid-assisted electrochemical oxidation (AEO) technique for mercury removal was proposed using platinum plate as cathode and fluorine-doped tin dioxide (FTO) glass as anode. The effects of acid type, acid concentration, applied direct current (DC) voltage, electrolyte type, SO2, NO and O2 on the Hg0 removal efficiency were carried out. The results indicated that the mercury removal efficiency increased with the increase of DC voltage and nitric acid concentration. When the concentration of nitric acid increased to 0.15 mol/L, the mercury removal efficiency remained unchanged. SO2 and NO inhibited the removal of Hg0 in AEO system, but the inhibition was reversible. Compared with the mercury removal efficiency under single experimental conditions, the mercury removal efficiency of electrochemical oxidation can reach 96% under the experimental conditions of 0.1 mol/L nitric acid and 4V DC voltage, suggesting that the synergistic effect of nitric acid and DC voltage plays a key role. According to the experimental results, the mechanism of Hg0 removal in AEO system was analyzed. At the anode, Hg0 was oxidized by hydroxyl radical (.OH) generated by the oxidation reaction on the anode surface. At the cathode, dissolved oxygen or O2 adsorbed on the surface of Pt is reduced to form anionic superoxide radicals (.O−2). Moreover, parts of .O−2 would produce .OH with the aid of electron at acidic condition. Free radicals capture experiments showed that .O−2 and .OH were the main active substances for the removal of Hg0 by acid-assisted electrochemical method. The research is helpful for the development of effective electrochemical techniques for industrial mercury removal and recycling of industrial acid waste.

Controlled Delivery of Celecoxib-β-Cyclodextrin Complexes from the Nanostructured Titanium Dioxide Layers.

Considering the potential of nanostructured titanium dioxide layers as drug delivery systems, it is advisable to indicate the possibility of creating a functional drug delivery system based on anodic TiO2 for celecoxib as an alternative anti-inflammatory drug and its inclusion complex with β-cyclodextrin. First, the optimal composition of celecoxib-β-cyclodextrin complexes was synthesized and determined. The effectiveness of the complexation was quantified using isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR) nuclear magnetic resonance (1H NMR), and scanning electron microscopy (SEM). Then, nanostructured titanium dioxide layers (TiO2) were synthesized using the electrochemical oxidation technique. The TiO2 layers with pore diameters of 60 nm and layer thickness of 1.60 µm were used as drug delivery systems. The samples were modified with pure celecoxib and the β-cyclodextrin-celecoxib complex. The release profiles shown effective drug release from such layers during 24 h. After the initial burst release, the drug was continuously released from the pores. The presented results confirm that the use of nanostructured TiO2 as a drug delivery system can be effectively used in more complicated systems composed of β-cyclodextrin-celecoxib complexes, making such drugs available for pain treatment, e.g., for orthopedic surgeries.

Electrochemical oxidation technique to pharmaceutical pollutants removal

Human progress in medical science and drug production has improved the growth process and increased human lifespan. Most of the drugs used are to control or prevent common human diseases. These drugs can be produced in different ways such as synthetic, chemical, biological, etc. On the other hand, pharmaceutical companies have a large volume of pharmaceutical effluents and wastewater that enters the environment and harms nature and human life. The main problems of entering the pharmaceutical effluent into the environmental cycle are the creation of drug resistance against the active substance of the drugs and the occurrence of abnormalities in the next generations. Therefore, the process of pharmaceutical wastewater treatment is used to reduce the level of pharmaceutical pollutants in order to enter the pharmaceutical wastewater into the environmental cycle. Until recently, filtration, passing through reverse osmosis and ion exchange resins, cleaning facilities, etc., have been various methods to remove pharmaceutical pollutants. Due to the low efficiency of the usual and old systems, the use of new methods has attracted more attention. In this article, the aim is to investigate the electrochemical oxidation method in order to remove the active ingredient of some commonly used drugs (aspirin, atorvastatin, metformin, metronidazole and ibuprofen) from the wastewater of pharmaceuticals. Therefore, in order to observe the initial conditions of the samples, a cyclic voltammetry diagram with a scanning rate of 100 mV/s has been performed. Next, by using the chronoamperometry process and applying a constant potential, the desired drugs were subjected to the electrochemical process of oxidation.As a result, the re-examined samples were subjected to cyclic voltammetry test to determine the conditions of sample oxidation peaks as well as the removal efficiency of the samples by examining the surface under the initial and final voltammetry graph. The results indicate that this method for removing selected drugs has a high removal efficiency of about 70% and 100% for atorvastatin samples. Therefore, this method is accurate, reproducible (RSD 2%), efficient, easy and economical and can be used in drug manufacturing industries. This method is used in a wide range of drug concentration. This means that by increasing the concentration of the drug, without the need to change the equipment used and the applied potential, by spending more time in the oxidation process, it is possible to remove very high amounts of the drug (more than 1000 ppm).

Copper and Copper Oxides Nanoparticles Synthesized by Electrochemical Technique in Chitosan Solution

A synthesis of chitosan copper and copper oxides nanoparticles (Cs-Cu, CuO) NPs via electrochemical technique has been reported. Chitosan copper complexes were prepared by electrochemical oxidation technique at duration time followed by reduction using different reducing agents for producing chitosan copper nanoparticles, Cs used as stabilizer and capping agent. The nanocomposites were characterized by using ultraviolet-visible spectroscopy (UV-vis). Transmission electron microscope (TEM) images were investigated emphasized formation the formation of NPs with different shapes. The average size of formed NPs is 28 nm. X-ray diffraction (XRD) is used to investigate the formation of the crystalline structure of prepared samples exhibited presence of copper and copper oxides in the formed complexes and nanocomposites. Analysis of FTIR showed chelation of Cu+2 with chitosan in complex form and electrostatic interaction between chitosan and copper nanoparticles.

Micromechanical properties of interfacial transition zone between carbon fibers and UHPC matrix based on nano-scratching tests

Ultra high performance concrete (UHPC) can be prepared by using carbon fiber (CF), instead of steel fiber, as reinforcement and indeed avoid the corrosion of steel fiber. The properties of CF/matrix interface play a key role on the composite performances. However, the properties of interface between CFs with different surface treatments and UHPC matrix are not yet clear. The denser matrix of UHPC makes the CF/matrix interface obviously different from that of ordinary concrete and more difficult to be characterized quantitatively. In this study, micromechanical properties of CF/matrix interface in UHPC were quantified using nano-scratch technique. Fracture toughness of the interface between UHPC matrix and CFs modified with electrochemical oxidation technique was higher than that of unmodified CF by about 51%. Moreover, the thickness of the interface transition zone decreased by more than 50%. Compared with the UHPC matrix without adding silica fume, 15% (by weight of cement) silica fume added to the UHPC matrix make the fracture toughness of CF/matrix interface increased by 17% and the interfacial thickness decreased by 37%.

Polishing of treated textile effluent using combined electrochemical oxidation and ozonation technique

Polishing of treated textile effluent using combined electrochemical oxidation and ozonation technique

A Review of Hybrid Process Development Based on Electrochemical and Advanced Oxidation Processes for the Treatment of Industrial Wastewater

Nowadays, increased human activity, industrialization, and urbanization result in the production of enormous quantities of wastewater. Generally, physicochemical and biological methods are employed to treat industrial effluent and wastewater and have demonstrated high efficacy in removing pollutants. However, some industrial effluent and wastewater contain contaminants that are extremely difficult to remove using standard physicochemical and biological processes. Previously, electrochemical and hybrid advanced oxidation processes (AOP) were considered a viable and promising alternative for achieving an adequate effluent treatment strategy in such instances. These processes rely on the production of hydroxyl radicals, which are highly reactive oxidants that efficiently break down contaminants found in wastewater and industrial effluent. This review focuses on the removal of contaminants from industrial effluents and wastewater through the integration of electrochemical and advanced oxidation techniques. These processes include electrooxidation, electrocoagulation/electroflocculation, electroflotation, photo-Fenton, ozone-photo-Fenton, sono-photo-Fenton, photo-electro-Fenton, ozone/electrocoagulation, sono-electrocoagulation, and peroxi/photo/electrocoagulation. The data acquired from over 150 published articles, most of which were laboratory experiments, demonstrated that the hybrid process is more effective in removing contaminants from industrial effluent and wastewater than standalone processes.

The Taguchi Approach in Studying and Optimizing the Electro-Fenton Oxidation to Reduce Organic Contaminants in Refinery Wastewater Using Novel Electrodes

This study investigated the degradation of organic pollutants using an advanced electrochemical oxidation technique in a batch reactor cell consisting of a graphite anode, modified by electrodeposition of PbO2, and a graphene-modified carbon fiber cathode. The experiment was designed by the Taguchi design approach with an orthogonal array of L18 to study and optimize the degradation of Chemical Oxygen Demand (COD) by the electro-Fenton oxidation process. Four process parameters, Current Density (CD), Temperature, Fe2+ concentration, and time were measured at different levels. The impact of each factor was analyzed by analysis of variance (ANOVA). Furthermore, a linear model analysis was applied for the Signal-to-Noise (S/N) ratio and mean values, obtaining the optimal conditions. The most significant parameter of the COD removal efficiency was time, and the least one was temperature.

High capacity and inexpensive multivalent cathode materials for aqueous rechargeable Zn-ion battery fabricated via in situ electrochemical oxidation of VO2 nanorods

For large-scale energy storage, aqueous rechargeable zinc-ion batteries are one of the most promising battery systems to replace lithium-ion batteries. In this study, a facile and scalable hydrothermal method is used to prepare VO2 nanorods, which are ball-milled with carbon black to prepare VO2@C nanoparticles. Characterizations using several advanced techniques confirm the successful synthesis of pure VO2 nanorods. Prior to electrochemical measurements, the VO2@C nanostructured cathode materials are transformed into V2O5·nH2O via an in situ electrochemical oxidation technique. The VO2@C/Zn aqueous zinc-ion full cell exhibits a reversible capacity of 300 mA h g−1 and a retention capacity of 85% after 1000 cycles at a current density of 5 A g−1 with a 2 M ZnSO4 electrolyte. The full cell also retains a remarkable capacity of 159 mA h g−1, even after 4000 galvanostatic charge–discharge cycles at 5 A g−1. The cell also shows excellent rate capabilities at a wide range of current densities from 0.1 to 20 A g−1, with a reversible discharge capacity and Coulombic efficiency of 100 mA h g−1 and 99%, respectively, at 20 A g−1. The remarkable performance is attributed to the nanoscale size of the prepared nanorods and the in situ electrochemical transformation.

Recent Progress in the Fabrication and Optical Properties of Nanoporous Anodic Alumina.

The fabrication of a thick oxide layer onto an aluminum surface via anodization has been a subject of intense research activity for more than a century, largely due to protective and decorative applications. The capability to create well-defined pores via a cost-effective electrochemical oxidation technique onto the surface has made a major renaissance in the field, as the porous surfaces exhibit remarkably different properties compared to a bulk oxide layer. Amongst the various nanoporous structures being investigated, nanoporous anodic alumina (NAA) with well-organized and highly ordered hexagonal honeycomb-like pores has emerged as the most popular nanomaterial due to its wide range of applications, ranging from corrosion resistance to bacterial repelling surfaces. As compared to conventional nanostructure fabrication, the electrochemical anodization route of NAA with well-controlled pore parameters offers an economical route for fabricating nanoscale materials. The review comprehensively reflects the progress made in the fabrication route of NAA to obtain the material with desired pore properties, with a special emphasis on self-organization and pore growth kinetics. Detailed accounts of the various conditions that can play an important role in pore growth kinetics and pore parameters are presented. Further, recent developments in the field of controlling optical properties of NAA are discussed. A critical outlook on the future trends of the fabrication of NAA and its optical properties on the emerging nanomaterials, sensors, and devices are also outlined.

Degradation of hexafluoropropylene oxide tetrameric acid (HFPO-TeA) using electrocatalytic ozone technique

Hexafluoropropylene oxide tetrameric acid (HFPO-TeA) is an alternative to perfluorooctanecarboxylic acid (PFOA) and is commonly used in the production of perfluoropolymers. In this study, the performances of ozone oxidation, electrochemical oxidation, and electrocatalytic ozone techniques in the degradation of HFPO-TeA were compared. The experimental results indicated that the electrocatalytic ozone technique was best. The effects of different current densities, ozone concentrations, electrolyte types, and initial pollutant concentrations on HFPO-TeA degradation were investigated. The results showed that the ratio of HFPO-TeA degradation reached 95.9% after electrolysis for 120 ​min for an initial HFPO-TeA concentration of 100 ​mg/L, a reaction volume of 120 ​mL, an applied current density of 10 ​mA/cm2, and an ozone concentration of 20 ​mg/L. The intermediate products detected were hexafluoropropylene oxide dimeric acid [C3F7OCF(CF3)COO−], pentafluoropropionic acid [C2F5COO−], and trifluoroacetic acid [CF3COO−]. The mechanisms involved in HFPO-TeA degradation include direct electron transfer, indirect oxidation mediated by hydroxyl radicals (·OH), and ozone oxidation.

Electrochemical degradation of indigo carmine by low voltage pulse electrolysis

Degradation of indigo carmine (IC) in aqueous solution via electrochemical oxidation (EO) was investigated by low voltage pulse electrolysis. The effects of experimental operating variables on total organic carbon(TOC) removal efficiency were studied, including initial pH, NaCl addition, charging voltage/frequency, and initial concentration of IC. The IC removal efficiency (in TOC) was higher under highly acidic or alkaline conditions, increased with the NaCl addition and an increase in charging voltage or frequency, but decreased with an increase in the initial concentration of IC. Intermediates formed during the degradation such as isatin-5-sulfonic acid (m/z = 226), 2-amino-α-oxo-5-sulfo-benzeneacetic acid (m/z = 242), 2-amino-5-sulfobenzoic acid (m/z = 198), and 2-amino-5-hydroxybenzoic acid (m/z = 152) were identified, on the basis of which a degradation pathway was proposed for the electrochemical degradation of IC in aqueous solution. The electrical energy consumption (Ec) in electrocatalytic oxidation was 159 kWh/kgTOC and the current efficiency is 15.3%. The EO technique on the basis of low voltage pulse electrolysis may be a promising approach to treatment of textile wastewater.

Synthesis and Photoelectrocatalytic Activity of Anodic Nanostructured TiO₂ Films

Nanostructured titanium dioxide films were prepared by electrochemical oxidation technique, anodization voltage effect on structure morphology, optical and photoelectrocatalytic performances of the nanotubes were studied. The anodization voltage is shown to significantly affect structure of nanofilms and, accordingly, their photoelectrocatalytic activity. An active heterojunction photoanode was synthesised with electrodeposition of Cu₂O onanodized TiO₂. The anode photoelectroact ivityunder bias 1V (Ag/AgCl/3,5M KCl) is found to be 15 % higher than that of the original nanostructured TiO₂ film