Photoelectrocatalytic Degradation Research Articles

Boron functionalized carbon-based metal-free catalyst for efficient photoelectrocatalytic degradation of pollutants

Boron functionalized carbon-based metal-free catalyst for efficient photoelectrocatalytic degradation of pollutants

Preparation of Bi4Ti3O12/TiO2 by flame spray pyrolysis for photoelectrocatalytic degradation of tetracycline

The negative effects of the irrational use of antibiotics have been increasing attention from the public, making it urgently needed to develop effective techniques for removing antibiotics from wastewater. Simultaneously, the construction of heterogeneous TiO2 photoanodes can be used to enhance photoelectrocatalytic performance. Herein, we used an advanced method, namely one-step flame spray pyrolysis (FSP) to in-situ prepare Bi4Ti3O12/TiO2 heterostructures. The ultra-high temperature characteristics of this method facilitated the high dispersion of Bi species on TiO2, leading to the formation of the Bi4Ti3O12 phase within milliseconds. Bi4Ti3O12 forms a "Z" type heterojunction with TiO2, improving charge separation and enhancing electron transfer efficiency. The photoeletrocatalytic degradation effect of Bi4Ti3O12/TiO2 on tetracycline is significantly improved. Under simulated sunlight irradiation for 75 min and 1V voltage, the removal of tetracycline can reach 99.7%. The recycling degradation experiments demonstrated the remarkable reusability and stability of Bi4Ti3O12/TiO2, while the evaluation of degradation intermediates and toxicity analysis of tetracycline were also conducted. Furthermore, free radical trapping experiments confirmed that hydroxyl radicals and holes play a significant role in the removal of tetracycline.

Novel Ag3PO4/ZnWO4-modified graphite felt electrode for photoelectrocatalytic removal of harmful algae: Performance and mechanism

A novel Ag3PO4/ZnWO4-modified graphite felt electrode (AZW@GF) was prepared by drop coating method and applied to photoelectrocatalytic removal of harmful algae. Results showed that approximately 99.21% of chlorophyll a and 91.57% of Microcystin-LR (MCLR) were degraded by the AZW@GF-Pt photoelectrocatalytic system under the optimal operating conditions with a rate constant of 0.02617 min−1 and 0.01416 min−1, respectively. The calculated synergistic coefficient of photoelectrocatalytic algal removal and MC-LR degradation by the AZW@GF-Pt system was both larger than 1.9. In addition, the experiments of quenching experiments and electron spin resonance (ESR) revealed that the photoelectrocatalytic reaction mainly generated •OH and •O2- for algal removal and MC-LR degradation. Furthermore, the potential pathway for photoelectrocatalytic degradation of MC-LR was proposed. Finally, the photoelectrocatalytic cycle algae removal experiments were carried out on AZW@GF electrode, which was found to maintain the algae removal efficiency at about 91% after three cycles of use, indicating that the photoelectrocatalysis of AZW@GF electrode is an effective emergency algae removal technology.

Ag-TiO2 Photovoltaic Synergistic Field-catalyzed Degradation Performance of Tetracycline

Background: Tetracycline (TC), a commonly used antibiotic, is extensively utilized in the medical sector, leading to a significant annual discharge of tetracycline effluent into the water system, which harms both human health and the environment. background: Tetracycline (TC), a commonly used antibiotic, is extensively utilized in the medical sector, leading to a significant annual discharge of tetracycline effluent into the water system. This harms both human health and the environment. Objective: A novel technique was developed to address the issues of photogenerated carrier complexation and photocatalyst immobilization. Compared to traditional photocatalytic photoelectrodes, the suspended catalyst used in the photovoltaic synergy field is more stable and increases the solidliquid contact area between the catalyst and the pollutant. objective: This paper uses sol-gel-prepared Ag-doped-TiO2 materials for the photoelectrocatalytic degradation of TC. Methods: This paper uses sol-gel-prepared Ag-doped-TiO2 materials for the photoelectric synergistic field-catalyzed degradation of TC. The study examined how the Ag doping ratio, calcination conditions, catalyst injection, pH, electrolytes, and electrolyte injection affected photoelectric synergistic field-catalyzed degradation. The experiments were performed in a photocomposite field with a constant 50 mA current and a 357 nm UV lamp for 60 minutes. The composites underwent characterization using XRD, TEM, and XPS techniques. method: The study examined how the Ag doping ratio, calcination conditions, catalyst injection, pH, electrolytes, and electrolyte injection affected photoelectrocatalytic activity. The experiments were done in a photocomposite field with a constant 50 mA current and a 357 nm UV lamp for 60 minutes. The composites underwent characterization using XRD, TEM, and XPS techniques. Results: Ag-TiO2 photoelectric synergistic field-catalyzed reaction with 357 nm ultraviolet lamp irradiation for 60 min and a constant current of 50 mA degraded 5 mg/LTC under preparation conditions of molar doping ratio of Ti: Ag=100:0.5, roasting temperature of 500 °C, and roasting time of 2 h. The photoelectric synergistic field-catalyzed degradation process achieved a degradation rate of 90.49% for 5 mg/L TC, surpassing the combined degradation rates of electrocatalysis and photocatalysis. The quenching experiments demonstrated that the degradation rate of TC decreased from 90.49% in the absence of a quencher to 53.23%, 42.58%, and 74.52%. The presence of •OH had a more significant impact than h+ and •O2-. Conclusion: The findings suggest that Ag-TiO2 significantly enhanced the efficacy of photoelectric synergistic field-catalyzed degradation and can be employed to treat high-saline and lowconcentration TC. This establishes a benchmark for using photoelectrocatalytic materials based on titanium in treating organic wastewater. result: Ag-TiO2 photoelectrocatalytic reaction with 357 nm ultraviolet lamp irradiation for 60 min and constant current (50 mA) degraded 5 mg/LTC under preparation conditions of molar doping ratio of Ti: Ag=100:0.5, roasting temperature of 500 °C, and roasting time of 2 h. The photoelectrocatalytic process achieved a degradation rate of 90.49 % for 5 mg/L TC, surpassing the combined degradation rates of electrocatalysis and photocatalysis. The quenching experiments demonstrated that the degradation rate of TC decreased from 90.49 % in the absence of a quencher to 53.23 %, 42.58 %, and 74.52 %. The presence of •OH had a more significant impact than h+ and •O2-.

Constructing core-shell structured Co3O4–MnWO4 composite photoelectrode with superior PEC water purification performance

Semiconductor photoelectrocatalytic (PEC) technology is one of the most effective methods for removing organic pollutants from wastewater in advanced oxidation processes(AOPs). The selection of suitable semiconductor materials as photoanodes is a crucial factor for achieving superior PEC performance. Here, a core-shell structured Co3O4–MnWO4 architecture is created by enveloping MnWO4 nanoparticles onto the surface of Co3O4 nanowires through a two-step hydrothermal process. The optimized Co3O4–MnWO4-5 photoelectrode showed superior PEC degradation efficiency for KN-R (∼91.2% in 2 h) and durable stability (the accelerated lifetime reached ∼9100 s at a current density of 50 mA cm−2). Three actual wastewaters were also collected to verify the practical applicability of the photoelectrode.The energy consumption was measured at 4.48 kWhm−3, with a COD removal efficiency of 83% and a decolorization rate of 98%. These results demonstrate the excellent performance and promising application of the photoelectrode. The enhancement of PEC performance for the core-shell structured Co3O4–MnWO4 architecture can be attributed to the suitable energy band structure of the Co3O4–MnWO4 composite, higher OEP, larger electrochemical active surface area, accelerated transport of interface carriers, and lower charge transfer resistance. The energy band structure of the Co3O4–MnWO4 composite showed a strong redox ability to induce electrons/holes (e−/h+), which enhances the generation of intermediate active species (hydroxyl radical ·OH and superoxide radicals ·O2-). Therefore, the rationally designed core-shell structured Co3O4–MnWO4 architecture exhibited excellent practical applicability in the degradation of organic pollutants.

LDH/MXene Synergistic Carrier Separation Effects to Improve the Photoelectric Catalytic Activities of Bi2WO6 Nanosheet Arrays.

Photoelectric catalysis is a green and efficient way to degrade pollutants, which has been paid more and more attention by researchers. Among them, Bi2WO3 has been proved to have excellent photocatalytic oxidation activity on its {001} facets. In this study, {001}-oriented facets with high exposure were successfully integrated into Bi2WO6 nanoplate arrays (Bi2WO6 NAs) to create a photoelectrode. This structure was grown in situ on an indium tin oxide (ITO) substrate. To promote photogenerated carrier separation efficiency and reduce agglomeration of Bi2WO6 photocatalysts, the electrochemical deposition of NiFe-layered double hydroxide (NiFe-LDH) and Ti3C2 (MXene) were introduced in this research to synergistically catalyze pollutant degradation. Morphology, spectral characterization, and electrochemical analysis jointly confirmed that the outstanding performance of hole capture behavior with LDH and electron conduction properties with MXene were the main reasons for the improvement in catalytic activity of the photoelectrode. Taking bisphenol A (BPA) as the model pollutant, the rate constant k of the NiFe-LDH/Ti3C2/Bi2WO6 NAs photoelectrode reaches 0.00196 min-1 under photoelectrocatalytic (PEC) conditions, which is 4.5 times that of the pure Bi2WO6 NAs photoelectrode. This work provides a new way to improve the reaction kinetics of the PEC degradation of pollutants.

Robust photoelectrocatalytic degradation of antibiotics by organic-inorganic PDISA/Bi2WO6 S-scheme heterojunction membrane

Ensuring the stability of the photoelectrode is paramount for optimal photoelectrocatalysis performance. In this investigation, a hybrid nanofiber film, incorporating the π-π conjugated self-assembly of perylene diimide monomers (PDISA) with Bi2WO6 (PDISA/Bi2WO6), was fabricated through the electrospinning process. Subsequently, this flexible electrospun film was pressed onto a Ni mesh to create a robust PDISA/Bi2WO6 electrode membrane. Results from photoelectrocatalytic studies reveal that the devised PDISA/Bi2WO6 photoanode significantly enhances the photoelectrocatalytic degradation efficiency of tetracycline (TC) and ciprofloxacin (CIP). Specifically, the apparent rate constants for the photoelectrocatalytic degradation of TC by 30%PDISA/Bi2WO6, compared to pristine PDISA and Bi2WO6, are elevated by 1.9 and 2.0 times, respectively. Moreover, the reaction rates of the photoelectrocatalytic (PEC) process surpass those of photocatalysis (PC) and electrocatalysis (EC) by 1.9 times and 8.0 times, respectively. Impressively, even after five cycles of PEC degradation of TC, the photoelectrode maintains 98.4% of its initial degradation rate, indicating its exceptional stability. These improvements in degradation efficiency and stability are attributed to the creation of the PDISA/Bi2WO6 S-scheme heterojunction membrane photoanode and the synergistic effects of photoelectrocatalysis.

Rod-like BiVO4 with two-phase structure to boost photoelectrocatalytic degradation activity for tetracycline via the p-n junction

Bismuth vanadate (BiVO4) as a potential photoanode is widely applied in photoelectrocatalytic (PEC) degradation flied. However, it is inhibited due to easy recombination of the photogenerated carries. Herein, rod-like morphology BiVO4 with monoclinic and tetragonal phase structure (R-BVO) are prepared using hydrothermal approach. Density functional theory (DFT) calculation confirms that the build-in electron field is constituted at contact interface of two-phase structure. Benefiting from the one-dimensional conduction of rod like morphology and the p-n junction formed by two-phase structure, R-BVO indicates outstanding photocurrent, the applied bias photo-to-current efficiency (ABPE) and the incident photoelectron conversion efficiency (IPCE). Compared with the single phase structure particle BiVO4 (P-BVO), the PEC degradation rate for TC of R-BVO is 96.4 %, which is 1.4 times of P-BVO. Equally importantly, the Ni foam is used as conducting substrate owing to its low cost and practicability, moreover, it is not only easy to determine catalyst dosage, but also ensures the tight contact between active substance and substrate, preventing the catalyst from peeling off in reaction. This study puts forward an adventurous strategy for designing effective photoanode materials.

Photoelectrode FTO/ Anodized TiO2 Production and Characterization for Methylene Blue Affected Photoelectrochemical Decomposition

Background: The production of thin film TiO2 nanostructured systems for electrocatalytic, photocatalytic, and photoelectrocatalytic applications has been an essential topic in recent years. Due to the light-sensitive effect of TiO2, it can be produced by various methods and used as a photoelectrode to remove dye. Using magnetron sputtering, Ti thin films can be deposited on different substrates and converted into transparent TiO2 structures by electrochemical anodization. Methods: In this study, the thin Ti film was produced using a magnetic spraying technique on the FTO substrate, and then an anodic TiO2 structure was obtained by the anodization technique. TiO2 films produced by the anodizing technique were used as a photoelectrode for the degradation of MB. The reactor contained 400 mL of 20 mg/L MB solution at 20 °C. The produced photoelectrode was characterized by the SEM/EDS, FTIR, XRD, and UV-Vis Spectrophotometer analyses. Results: The EDS analysis confirmed the presence of titanium and oxygen in the FTO/ Anodized TiO2 photoelectrode. The XRD results showed that all the peaks of the produced FTO/ Anodic TiO2 were associated with the anatase phase of TiO2. According to the FTIR spectroscopy, the functional groups of the anodized TiO2 were obtained for the FTO/ Anodized TiO2. The electrocatalytic, photocatalytic, and photoelectrocatalytic degradation experiments were performed with the degradation of the dye solution of MB on the FTO/ Anodic TiO2 photoelectrode, and the rates of dye degradation were determined as 17.12%, 64.67%, and 82.12%, respectively Conclusion: This study showed that the methylene blue dye of FTO/ Anodic TiO2 is a suitable photoelectrode for electrocatalytic, photocatalytic, and photoelectrocatalytic degradation.

Photoelectrocatalytic degradation of high-density polyethylene microplastics on TiO2-modified boron-doped diamond photoanode

Microplastic (MP) accumulation in the environment is accelerating rapidly, which has led to their effects on both the ecosystem and human life garnering much attention. This study is the first to examine the degradation of high-density polyethylene (HDPE) MPs via photoelectrocatalysis (PEC) using a TiO2-modified boron-doped diamond (BDD/TiO2) photoanode. This study was divided into three stages: (i)preparation of the photoanode through electrophoretic deposition of synthetic TiO2 nanoparticles on a BDD electrode; (ii) characterization of the modified photoanode using electrochemical, structural, and optical techniques; and (iii) degradation of HDPE MPs by electrochemical oxidation and photoelectrocatalysis on bare and modified BDD electrodes under dark and UV light conditions. The results indicate that the PEC technique degraded 89.91± 0.08% of HDPE MPs in a 10-h reaction and was more efficient at a lower current density (6.89 mA cm-1) with the BDD/TiO2 photoanode compared to electrochemical oxidation on bare BDD.

Fabrication of WO3 nanorod arrays modified by BiOBr and their enhanced photoelectrocatalytic activity

BiOBr/WO3 nanorod array (NRA) composite photoelectrodes were successfully prepared using a solvothermal method. The instrumental characterisation of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, incident photoelectric conversion efficiency and ultraviolet diffuse reflectance indicates that the obtained BiOBr/WO3 NRAs exhibit good crystallinity and purity, and they can utilise light with wavelengths less than approximately 440 nm. On the surface of the WO3 nanorods, BiOBr thin nanosheets grow uniformly with strong adhesion and a 3D structure. The composite photoelectrode loaded with an appropriate amount of BiOBr (labelled BW-1 NRA) exhibits the best photoelectrocatalytic (PEC) activity. The PEC degradation efficiency of 10 mg/L of bisphenol A reached 95.7 % after 3 h at 1.0 V bias voltage. This value is 2.8 times that of individual photocatalytic degradation. After four times of recycling, the decrease in catalytic activity is insignificant, indicating the good stability of the catalyst. By analysing the results of the photoelectrochemical properties, band structures and types of free radicals, a conclusion is drawn that the excellent catalytic performance of BW-1 NRA is ascribed to the following aspects. (1) The formation of the p–n heterojunction by BiOBr and WO3 can effectively separate photogenerated electrons and holes. (2) Bias drives the migration of photogenerated electrons to the external circuit, further preventing the recombination of photogenerated electrons and holes. (3) The 3D structure of the photoelectrode has a large specific surface area and multiple active sites, improving light absorption and utilisation efficiency.

Surface-surface contacted direct Z-scheme TiO2-BiVO4-PI heterostructure for enhanced photoelectrocatalytic degradation of bisphenols under solar driven

Bisphenols (BPs) are a series of widely used endocrine disruptors, which potentially harm the environment and human health. In this work, a novel Z-scheme TiO2-BiVO4-PI heterostructure was synthesized, characterized, and used for the simulated sunlight-driven photoelectrocatalytic degradation of BPs. Due to the existence of surface-surface contacted direct Z-scheme between BiVO4 and PI, holes were concentrated on the valence band of BiVO4 and electrons were concentrated on the conduction band of PI, resulting in a stronger redox activity. All six BPs exhibited appreciable degradation following the order of bisphenol A (BPA, 93.5%) > bisphenol B (BPB, 92.7%) > bisphenol AP (BPAP, 85.6%) > bisphenol F (BPF, 75.9%) > bisphenol AF (BPAF, 69.8%) > bisphenol S (BPS, 39.2%), within 120 min under the optimal condition. In the process of degradation, superoxide radicals (·O2−) and hydroxyl radicals (·OH) played dominant roles, and the intermediates of BPs degradation were mainly formed via the substituent shedding or C–C bond breaking of phenol ring, hydroxylation, and ring opening of phenol ring. The ECOSAR program was used to analyze the changes in the toxicity of the intermediates, and it was proved that the toxicity showed a decrease trend during the degradation process. This study provides a Z-scheme mechanism for TiO2-BiVO4-PI, which can degrade BPs and reduce their toxicity effectively.

Unlocking a Type-II CoO@BiVO4 Heterostructure for Wastewater Purification.

Developing a semiconductor-based heterostructure photoanode is crucial in improving the photoelectrocatalytic (PEC) efficiency for degrading refractory organic pollutants. Nevertheless, the PEC performance of the photoanodes is usually restricted by electron/hole pair recombination, oxygen evolution, and slow electron transfer. Herein, a novel CoO@BiVO4 nanowire array film (Ti/CoO@BiVO4) with n-type semiconductor characteristics was prepared via a straightforward hydrothermal method. The optimized Ti/CoO@BiVO4 electrode exhibited excellent PEC decolorization efficiency of active brilliant blue KN-R (∼92.8%) and long-term stability, outperforming recent reports. The insight reason for enhancing the PEC degradation efficiency of the Ti/CoO@BiVO4 electrodes can be attributed to the large electrochemical active area, low charge transfer resistance, and negative flat band potential. The formation of a type-II heterostructure was investigated between CoO and BiVO4 further to promote the generation and separation efficiency of electron/hole pairs, indicating that the optimized Ti/CoO@BiVO4 electrode has the potential for the water PEC degradation ability and superior service life.

SnO2/Fe2O3/Cu2O composites as catalysts for photoelectrocatalytic degradation of benzotriazoles

Benzotriazole (BTA) is a kind of nitrogen-containing organic matter with great impact on the environment and biology. In order to further improve the degradation effect of BTA, SnO2/Fe2O3/Cu2O (SFC) photocatalytic materials have been successfully prepared by one-pot hydrothermal method. According to the material characterization and experimental results, SFC has a uniform distribution of active sites, which is conducive to the efficient degradation of BTA in water. When the pH is 6.68, the dosage is 0.09 g/L, and the time is 40 min, the degradation effect is the best. The removal rate of BTA by SFC reached 99.89 %. The repeatability test showed that the removal rate of SFC can reach more than 99.27 % after five cycles of experiments.Through PL, UV–Vis and i-t curve analysis, it proved the main mechanism of degradation of BTA by PEC enhanced by SFC. Finally, the possible degradation pathways of BTA were speculated, which provided a new technical support and theoretical basis for the effective treatment of wastewater containing BTA.

Light concentration and electron transfer in plasmonic-photonic Ag,Au modified Mo-BiVO4 inverse opal photoelectrocatalysts.

Plasmonic photocatalysis based on metal-semiconductor heterojunctions is considered a key strategy to evade the inherent limitations of poor light harvesting and charge separation of semiconductor photocatalysts. It can be profitably combined with three-dimensional photonic crystals (PCs) that offer an ideal scaffold for loading plasmonic nanoparticles and a unique architecture to intensify photon capture. In this work, Mo-doped BiVO4 inverse opals were applied as visible light-responsive photonic hosts of Ag and/or Au plasmonic nanoparticles in order to exploit the synergy of plasmonic and photonic amplification effects with interfacial charge transfer for the photoelectrocatalytic degradation of recalcitrant pharmaceutical contaminants under visible light. Photoelectrochemical evaluation indicated a major contribution from hot spot-assisted local field enhancement, most pronounced for Ag/Mo-BiVO4 PCs due to the spectral overlap of the localized surface plasmon resonance with the electronic absorption and blue-edge slow photon region of Mo-BiVO4 PCs, in contrast to weak plasmonic sensitization effects for the Au-modified PCs. The diverse band alignment at the metal-semiconductor interfaces resulted in the enhanced photoelectrocatalytic degradation of tetracycline broad spectrum antibiotic by Ag/Mo-BiVO4 and the refractory ibuprofen drug by (Ag,Au)/Mo-BiVO4, attributed to the enhanced charge separation by electron transfer toward Ag nanoparticles. Combination of visible light activated semiconductor PCs and plasmonic nanoparticles with suitable band alignment and photonic band gap may provide a versatile approach for the rational design of efficient plasmonic-photonic photoeletrocatalysts.

Effluent toxicity study using biomarkers for ciprofloxacin photoelectrocatalytic degradation by bismuth-doped titanium dioxide nanotubes

ABSTRACT Ciprofloxacin hydrochloride (CIP) is a broad-spectrum synthetic antibiotic often found in domestic sewage and industrial waste due to the inefficiency of conventional treatments. Given the potential risk of drug accumulation, this study presents coatings of titanium dioxide nanotubes (TiO2) doped with different bismuth (Bi) concentrations to degrade CIP through photocatalytic and photoelectrochemical processes. Characterization studies revealed that bismuth (Bi) doping affected the morphology of the materials, with concentrations of 0.01 and 0.05 mol L−1, resulting in collapsed materials with a smaller active surface area. Photocatalysis tests for all the materials exhibited a similar degree of efficiency to photolysis, approximately 33%. Ecotoxicity tests using the biomarkers Lactuca sativa L., Lemna minor, and Artemia salina indicated that, although they were similar to photolysis in terms of efficiency, the effluents generated when employing the doped catalysts showed lower levels of toxicity, with the best results achieved for the material doped with 0.005 mol L−1 of Bi, with a toxicity level approximately 40% lower. Photoelectrocatalysis proved to be the most efficient CIP degradation technique. The highest degradation rate was observed for materials doped with 0.005 mol L−1 of Bi, with an efficiency of 46%, which is 1.4 times more efficient than photolysis. These results demonstrate that materials doped with low amounts of Bi can be effectively used as photoanodes for drug degradation, as their performance is superior, and the final product generated exhibits low toxicity to living organisms.

The improvement of photocatalytic activity of BiVO4 modified with Co(OH)2 nanoflake arrays for photocatalytic and photo-electrocatalytic desulfurization

Various and economical pure BiVO4 and Co(OH)2 nanoflake deposited BiVO4 photocatalysts have been prepared using the electrodeposition technique. Improved photocurrent density of 64 µA/cm2 at 1.0 V vs. Ag/AgCl was shown by Co(OH)2-BiVO4-150 photoanode (BiVO4 after 150 s of cobalt electrodeposition), which is about 8 times higher compared with BiVO4 photoanode. The catalysts prepared have also been used in the photocatalytic oxidation of dibenzothiophene (DBT), which is applied to stimulate fluid catalytic cracking for gasoline production in n-heptane solution. The corresponding parameters in the optimization of oxidative desulfurization of DBT were reaction time, temperature, solvent, DBT concentration and electrical bias voltage. The highest DBT desulfurization efficiency was shown by Co(OH)2-BiVO4-150. Based on the mechanism of photocatalytic oxidation, the superoxide and hydroxyl radicals played major parts in DBT degradation. Co(OH)2-BiVO4-150 photoanode showed better photo-electrocatalytic degradation efficiency, reaching a high 78.3% DBT removal even during the reaction time, in comparison with photocatalysis and electrocatalysis. The photocatalytic degradation system containing Co(OH)2-BiVO4-150 may be recycled six times without any important reduction of photocatalytic activity. This procedure introduces a simple and sustainable approach for the modification of BiVO4 to improve its photoelectrochemical and photocatalytic activity.

Photo-electrocatalytic degradation of remdesivir from aqueous solutions using Ni-doped ZnO nanocomposite: Kinetic, degradation pathway, toxicity reduction and reusability

Currently, there has been increasing interest in developing active photocatalysts for the treatment of wastewaters. In this study, Nickel (Ni)-doped Zinc oxide on a fluorine tin oxide (ZnO/FTO) was synthesized and utilized as an electrocatalyst for efficient degradation and mineralization of remdesivir (REMD). Ni-ZnO/FTO electrode was characterized using XRD, SEM, EDX, LSV, and DRS analyses. The influence of operational parameters on the degradation efficiency procedure was explored in a batch photo-reactor and their optimum values were selected. At optimized conditions (e.g. initial REMD concentration = 1 mg/L, electrolyte concentration = 0.1 g/L, current intensity = 0.03 A, and pH = 7), within 2 h under UV-A, the removal efficiency of initial REMD concentration was 92 %, whereas TOC and COD removal efficiency were found as 80.1 % and 69.5 %, respectively. The assessment of the degradation rate within 2 h indicates that REMD degradation obeyed first order kinetic model. Additionally, in the comparison of degradation and mineralization efficiency of electrolysis, photolysis and photocatalytic and photoelectrocatalysis (PECP) processes for REMD removal, PECP gave the highest efficiency. The toxicity evaluations showed that the toxicity of solutions treated by the proposed PEC process significantly decreased in comparison with untreated controls. Based on reusability investigations, Ni-ZnO/FTO can be reused for at least five repetitive times with suitable efficiency. Moreover, by taking into account all results, it was concluded that the affordability, high potentiality, and well regenerability of Ni-ZnO/FTO make it an attractive electrocatalyst in terms of drug-containing wastewater treatment.

Electrochemical Sensing and Photoelectrodegradation of Pentachlorophenol using Co‐, Mn‐ and Zn‐Porphyrins

AbstractIn this work, we present Zn, CoII, and MnIII metalated meso‐tetra‐[4‐(methylthio) phenyl] porphyrin ([Zn(TMtPP)], [CoII(TMtPP], and [MnIII(TMtPP)Cl]) as electrocatalysts and photoelectrocatalysts for electrochemical detection and photoelectrocatalytic degradation of pentachlorophenol (PCP). The complexes were characterized using UV‐visible spectroscopy, mass spectroscopy, and elemental analysis. Proton nuclear magnetic resonance (1H NMR) studies were only conducted for the Zn derivative. The electrochemical detection of PCP was carried out using cyclic voltammetry and chronoamperometry. [CoII(TMtPP)] showed better detection limit. For photoelectrocatalytic (PEC) degradation studies of PCP, linear sweep voltammetry and UV‐visible spectra were employed. [Zn(TMtPP)] showed better removal efficiency. The main species responsible for the PEC degradation were found to be superoxide radicals (⋅O2) and electron holes (h+).

Photoelectrocatalytic Processes of TiO2 Film: The Dominating Factors for the Degradation of Methyl Orange and the Understanding of Mechanism.

Various thicknesses of TiO2 films were prepared by the sol-gel method and spin-coating process. These prepared TiO2 films exhibit thickness-dependent photoelectrochemical performance. The 1.09-μm-thickTiO2 film with 20 spin-coating layers (TiO2-20) exhibits the highest short circuit current of 0.21 mAcm-2 and open circuit voltage of 0.58 V among all samples and exhibits a low PEC reaction energy barrier and fast kinetic process. Photoelectrocatalytic (PEC) degradation of methyl orange (MO) by TiO2 films was carried out under UV light. The roles of bias, film thickness, pH value, and ion properties were systematically studied because they are the four most important factors dominating the PEC performance of TiO2 films. The optimized values of bias, film thickness, and pH are 1.0 V, 1.09 μm, and 12, respectively, which were obtained according to the data of the PEC degradation of MO. The effect of ion properties on the PEC efficiency of TiO2-20 was also analyzed by using halide as targeted ions. The "activated" halide ions significantly promoted the PEC efficiency and the order was determined as Br > Cl > F. The PEC efficiency increased with increasing Cl content, up until the optimized value of 30 × 10-3 M. Finally, a complete degradation of MO by TiO2-20 was achieved in 1.5 h, with total optimization of the four factors: 1.0 V bias, 1.09-μm-thick, pH 12, and 30 × 10-3 M Cl ion content. The roles of reactive oxygen species and electric charge of photoelectrodes were also explored based on photoelectrochemical characterizations and membrane-separated reactors. Hydrogen peroxide, superoxide radical, and hydroxyl radical were found responsible for the decolorization of MO.