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PHOTOELECTROCHEMICAL ANALYSIS OF TITANIUM DIOXIDE BY USING OXALIC ACID AS A SACRIFICIAL DONOR
摘要： Photoelectrochemical (PEC) water splitting is a very promising green method to produce solar fuel. Titanium dioxide (TiO2) has been widely used as photocatalyst for this type of reaction. Improving the performance of TiO2 for PEC water splitting has been ongoing and addition of sacrificial donor especially from waste is an attractive option to achieve this. Oxalic acid is one component in organic waste stream that can be used as sacrificial donor. The TiO2 thin films has been fabricated by coating TiO2 paste on Fluorine Tin oxide (FTO) glass surface. The morphology of the TiO2 thin films were porous and rough with uniform particles size with crystallite size of about 20 nm and dominant anatase peak. The TiO2 photoelectrode undergo PEC testing to measure its photolectroactivity by using oxalic acid as a sacrificial donor in two different type of electrolytes which are distilled water and sodium sulfate (NA2SO4) aqueous solution. The photocurrent produced without addition of oxalic acid is much lower than with the acid. The saturation photocurrent for aqueous NA2SO4 solution and water electrolyte is 0.1 mA/cm2 and negligible respectively. While the photocurrent for addition of oxalic acid in NA2SO4 aqueous solution is 0.5 mA/cm2 and the photocurrent for oxalic acid in water only is 0.9 mA/cm2, which is almost double compared to in NA2SO4 and tenfold in water only. The highest photocurrent produced by TiO2 photoelectrode is by addition of oxalic acid in aqueous (H2O) electrolyte.
关键词： photoelectrochemical cell,titanium dioxide,donor,oxalic acid,Water splitting
更新于2025-09-04 15:30:14
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Fabrication of SnS <sub/>2</sub> /SnS Heterojunction with Enhanced Light-Assisted Electrochemical Water Splitting Performance
摘要： Semiconducting metal sul?des have raised strong research interest among researchers as a promising candidate for light-assisted electrochemical water splitting, because they have wide band gap. In order to harvest more light wavelengths for improvement of light-assisted electrochemical water splitting capacity, we fabricated SnS2/SnS heterojunction nanosheets via facile and environmental route. The SnS2/SnS heterojunction nanosheets were used as photo-electrocatalytic material which exhibited low over potential of ?0.64 V at the current density of 10 mA · cm?2 in 0.5 M NaSO4 solution. Moreover, the SnS and SnS2 nanosheets displayed high over potential values of ?0.80 and ?0.88 V at the current density of 10 mA · cm?2, respectively. This research ?nding may therefore show the potential for use of SnS2/SnS heterojunction nanosheets as low cost and environmentally friendly photo-electrocatalysis.
关键词： SnS2/SnS Heterojunction,SnS2 Nanosheet,SnS Nanosheet,Light-Assisted Electrochemical Water Splitting
更新于2025-09-04 15:30:14
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Construction of Ti3+ self-doped TiO2/BCN heterojunction with enhanced photoelectrochemical performance for water splitting
摘要： Ti3+ self-doped TiO2/BCN heterojunction (Ti3+-TiO2/BCN) was constructed via a hydrothermal method with using NaBH4 as reducing agent. The BCN nanosheets function as a good support to block the agglomeration of Ti3+-TiO2 nanoparticles, which decreased the recombination of photogenerated charge carriers. The Ti3+-TiO2/BCN sample exhibited enhanced electronic conductivity and absorption in visible light region because of the introduction of Ti3+ and oxygen vacancies (Ov). The as-prepared Ti3+-TiO2/BCN sample showed enhanced photoelectrochemical (PEC) performance as confirmed by analyses of LSV, EIS, Bode plots and M–S. Under the visible light irradiation, the optimally Ti3+ self-doped TiO2/BCN heterojunction sample yield a photocurrent density of ～ 0.69 mA/cm2 at 1.23 V versus RHE, which is over three times as high as BCN and TiO2/BCN at the same conditions.
关键词： hydrothermal method,photoelectrochemical performance,NaBH4,water splitting,Ti3+ self-doped TiO2/BCN heterojunction
更新于2025-09-04 15:30:14
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A two-photon excited O2-Evolving Nanocomposite for Efficient Photodynamic Therapy against hypoxic tumor
摘要： This paper reported on a two-photon excited nanocomposite FCRH to overcome tumor hypoxia for enhanced photodynamic therapy (PDT). Through modified by ruthenium (Ⅱ) complex (Ru(bpy)3 2+) and hyperbranched conjugated copolymer with poly (ethylene glycol) arms (HOP), the water-splitting mediated O2 generation from iron-doped carbon nitride (Fe-C3N4) can be triggered via two-photon irradiation for the first time. While exposured to two-photon laser, Ru(bpy)3 2+ was activated to generate singlet oxygen (1O2) and Fe-C3N4 was triggered to split water for oxygen supply in the mean time. Owing to the injection of photoinduced electrons from excited Ru(bpy)3 2+ to Fe-C3N4, O2 generated by Fe-C3N4 was significantly accelerated. After accumulation of the nanocomposite by enhanced permeability and retention (EPR) effect, FCRH was demonstrated to alleviate the tumorous hypoxia and consequently enhance the antitumor efficacy of PDT. Furthermore, tumor metabolism evaluations explained the capability of the nanocomposite in reducing intratumoral hypoxia. Our results provide a new diagram for ameliorating the hypoxic tumor microenvironment and accelerating 1O2 generation under two-photon excitation, which will find great potential for spatiotemporally controlled tumor treatment in vivo.
关键词： two-photon,water splitting,oxygen generation,tumor hypoxia,photodynamic therapy
更新于2025-09-04 15:30:14
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Water reduction into hydrogen using Rh-doped SrTiO3 photoelectrodes surface-modified by minute amounts of Pt: Insights from heterogeneous kinetic analysis
摘要： In this paper, we report on the photoelectrochemical hydrogen evolution reaction (HER) from water using Rhodium-doped strontium titanate, surface-modified by the addition of minute amounts of platinum nanoparticles. Platinum has been used in an attempt to increase the charge transfer efficiency of the photoelectrode but also to investigate the balancing effect of surface co-catalysis on charge transfer versus recombination processes. The dynamics of the HER in pH-neutral aqueous solutions has been investigated by Photoelectrochemical Impedance Spectroscopy. Experimental impedance data has been analyzed using a model derived from considerations on heterogeneous kinetics. From the best experimental vs. calculation PEIS fits, microscopic rate parameters have been determined over an extended range of electrical potential. The charge transfer (kt ) and recombination (kr) rate constants have been found to vary exponentially with the applied potential. The analysis of the potential dependence of kt led to a Butler-Volmer transfer coefficient of 0.21. The analysis of the potential dependence of the recombination rate constant kr led to the determination of a non-ideality factor b ? 0.04 (b ? 1 for ideal interfaces), demonstrating the strong non-ideal behavior of the interface. Such non-ideal behavior has been attributed to the presence of a high density of surface states. The space charge capacitance under inversion conditions, i.e. when a strong reversed bias is applied and when the surface of this p- semiconductor exhibits a n-type conductivity, has also been measured and analyzed.
关键词： Water splitting,Kinetics,Photoelectrochemistry,Hydrogen
更新于2025-09-04 15:30:14
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Evaluation of electroless Pt deposition and electron beam Pt evaporation on p-GaAs as a photocathode for hydrogen evolution
摘要： This study examines the changes in the photoelectrochemical (PEC) properties with Pt morphology after wet (electroless Pt deposition) and dry (e-beam Pt evaporation) deposition of Pt on p-GaAs. The Pt morphology and composition of the p-GaAs surface differed depending on the Pt deposition method, which in turn affected the optical and PEC properties of Pt on the GaAs electrode. Thus, the findings of this study can help in gaining a clearer understanding of the manner in which these changes affect the operation of a GaAs PEC water-splitting electrode.
关键词： Electrocatalyst,Electron beam evaporation,Gallium arsenide,Water splitting,Electroless deposition,Platinum
更新于2025-09-04 15:30:14
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Bimetallic PtAu Alloy Nanoparticles-Integrated g-C <sub/>3</sub> N <sub/>4</sub> Hybrid as an Efficient Photocatalyst for Water-to-Hydrogen Conversion
摘要： Herein, we report the synthesis of metal (Pt and Au) and metal alloy (PtAu) nanoparticles (NPs) integrated graphitic carbon nitride (g?C3N4) hybrid using a facile solvothermal route for water splitting application. The metal and metal alloy NPs with varying percentages of Pt and Au are found to be in the size range of 3?5 nm and uniformly distributed on the g?C3N4 sheets. The metal and metal alloy NPs act as cocatalyst for g?C3N4 to enhance the photocatalytic activity for hydrogen (H2) generation through higher light absorption and efficient charge separation. The alloy composition plays an important role to maximize the photoactivity, with an optimized PtAu/g?C3N4 sample delivered 1009 μmol g?1 h?1 of H2. The visible light assisted photocatalytic H2 evolution is further investigated with the optimized PtAu alloy NPs integrated g?C3N4. This study presents a robust, stable, and easily synthesizable PtAu/g?C3N4 hybrid material as a promising photocatalyst for H2 generation through water splitting.
关键词： alloy nanoparticles,heterostructure,g?C3N4,water splitting,bimetallic,photoelectrochemical
更新于2025-09-04 15:30:14
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Energy Level Engineering in Transition-Metal Doped Spinel-Structured Nanosheets for Efficient Overall Water Splitting
摘要： Unraveling the role of transition-metal doping on affecting the native spinel-structured nanosheets’ water splitting remains a grand challenge. In this work, a series of spinel-structured nanosheets wrapped hollow nitrogen-doped carbon polyhedrons was constructed, and doped transition-metal domains were deliberately introduced on the surface. Theoretical investigations show that their energy level can be finely tuned via direct transition-metal doping engineering. As a prototype, Fe-doped NiCo2O4 nanosheets wrapped hollow nitrogen-doped carbon polyhedron (Fe-NiCo2O4@HNCP) exhibits outstanding bifunctional electrocatalytic performances with low overpotentials (η = 270 mV for OER, η = 84 mV for HER), low Tafel slopes (b = 42 mV dec-1 for OER, b = 47 mV dec-1 for HER), and high durability. The enhanced performance is attributed to the synergistic effects of energy level matching for electron transfer, and partial charge delocalization-induced rich active sites for reactant adsorption via thermodynamic and kinetic acceleration. This work may open a new pathway to design highly active and stable transtion-metal doped electrocatalysts by manipulated energy levels for efficient overall water splitting.
关键词： energy level engineering,water splitting,electrocatalysts,spinel-structured nanosheets,transition-metal doping
更新于2025-09-04 15:30:14
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Suppression of poisoning of photocathode catalysts in photoelectrochemical cells for highly stable sunlight-driven overall water splitting
摘要： A photoelectrochemical (PEC) cell composed of two semiconductor electrodes, a photocathode, and a photoanode is a potentially effective means of obtaining hydrogen through spontaneous overall water splitting under light irradiation. However, the long-term stability (that is, operation for more than one day) of a PEC cell has not yet been demonstrated. In addition to the corrosion of both photoelectrodes, the gradual migration of heavy metal cations from the photoanode into the electrolyte can also result in degradation of the cell by contamination of the photocathode surface. In the present work, BiVO4-based photoanodes were used in conjunction with two different modifications: dispersion of a chelating resin in the electrolyte and coating of the photoanode surface with an anion-conducting ionomer. The chelating resin was found to capture Bi3+ cations in the electrolyte before they became deposited on the cathode surface. Consequently, a PEC cell incorporating a BiVO4-based photoanode and a (ZnSe)0.85(CuIn0.7Ga0.3Se2)0.15-based photocathode showed stable overall water splitting over a span of two days under simulated sunlight. To the best of our knowledge, this represents the longest period over which stable PEC cell performance has been established. A considerable decrease in the performance of the BiVO4-based photoanode was still observed due to the continuous dissolution of Bi species, but surface coating of the photoanode with an anion-conducting ionomer prevented the movement of Bi3+ ions into the electrolyte because of the selective conduction of ions. The coating also served as a protective layer that improved the durability of the photoanode. This study therefore suggests a simple yet effective method for the construction of stable PEC cells using semiconductor photoelectrodes.
关键词： chelating resin,photoanode,stability,BiVO4,anion-conducting ionomer,water splitting,photoelectrochemical cell,photocathode
更新于2025-09-04 15:30:14
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Electrodeposition and characterization of SnS-electrochemically reduced graphene oxide heterojunction
摘要： This work shows the formation of a heterojunction between tin (II) sulfide (SnS) and electrochemically reduced graphene oxide (ERGO) carried out through two electrochemical steps. In the first step, graphene oxide (GO) was electrochemically reduced on a fluorine-doped tin oxide (FTO) electrode. In the second step, the ERGO/FTO substrate was used as an electrode for the electrodeposition of SnS. In this study, each material electrodeposited (ERGO, SnS and SnS/ERGO heterojunction) was analyzed and characterized using different techniques, which confirmed the SnS/ERGO heterojunction formation. By employing electrochemical impedance spectroscopy (EIS) and linear sweep photovoltammetry measurements, it was confirmed that SnS deposited in both, bare FTO and ERGO, is a p-type semiconductor. Furthermore, an improvement of the photocatalytic properties of the SnS/ERGO photocathode in comparison with the SnS film was observed. This effect is related to the ERGO interlayer between the SnS film and the FTO electrode, and the structural and morphology modification of the SnS film onto ERGO.
关键词： semiconductors,electrodeposition,water splitting,graphene oxide,thin films
更新于2025-09-04 15:30:14