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Photoelectrochemical Gas–Electrolyte–Solid Phase Boundary for Hydrogen Production From Water Vapor
摘要： Hydrogen production from humidity in the ambient air reduces the maintenance costs for sustainable solar-driven water splitting. We report a gas-diffusion porous photoelectrode consisting of tungsten trioxide (WO3) nanoparticles coated with a proton-conducting polymer electrolyte thin film for visible-light-driven photoelectrochemical water vapor splitting. The gas–electrolyte–solid triple phase boundary enhanced not only the incident photon-to-current conversion efficiency (IPCE) of the WO3 photoanode but also the Faraday efficiency (FE) of oxygen evolution in the gas-phase water oxidation process. The IPCE was 7.5% at an applied voltage of 1.2 V under 453 nm blue light irradiation. The FE of hydrogen evolution in the proton exchange membrane photoelectrochemical cell was close to 100%, and the produced hydrogen was separated from the photoanode reaction by the membrane. A comparison of the gas-phase photoelectrochemical reaction with that in liquid-phase aqueous media confirmed the importance of the triple phase boundary for realizing water vapor splitting.
关键词： proton exchange membrane,solar H2 production,tungsten oxide photoanode,visible-light-driven photoelectrode,gas-phase water splitting
更新于2025-09-09 09:28:46
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How does cobalt phosphate modify the structure of TiO2 nanotube array photoanodes for solar water splitting?
摘要： TiO2 nanotube arrays (TNA) have been modified by cobalt phosphate (CoPi) through potentiostatic electrodeposition method. Different samples have been prepared by changing the loaded CoPi through the deposition time from 10 to 960 minutes. Formed catalytic materials have been characterized by different methods. Although charge transfer resistance of the CoPi/TNA photoanodes have been decreased from 5.5 to 4.0 kΩ by increasing the deposition time from 5 to 60 minutes, the maximum photoresponse was obtained for 10 min CoPi deposition leading to 24% more photocurrent compare to bare TNA which proposed optimum value for cobalt phosphate decoration. Based on field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) results, by depositing the electrocatalyst, nanotube walls have been spread and holes have been covered by CoPi. Correlation between observed change in surface morphology and Raman spectra of the samples along with electrocatalytic tests revealed how decoration time can influence structural properties and photoelectrochemical performance of the final CoPi/TNA photoanodes in solar water splitting system.
关键词： CoPi,TiO2 photoanode,photoelectrochemical performance,solar water splitting
更新于2025-09-09 09:28:46
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Boosted Water Oxidation Activity and Kinetics on BiVO <sub/>4</sub> Photoanodes with Multihigh-Index Crystal Facets
摘要： The crystal facet of the BiVO4 photoanode has potential influence on its charge-transfer and separation properties as well as water oxidation kinetics. In the present work, a BiVO4 polyhedral film with exposed {121}, {132}, {211}, and {251} high-index facets was synthesized by a facile Bi2O3 template-induced method and investigated as a photoanode for water oxidation. In comparison with the normal BiVO4 film with a {121} monohigh-index facet, the BiVO4 film with multihigh-index crystal facets shows higher activity and faster kinetics for photoelectrochemical water oxidation. Specifically, a higher photocurrent density of 1.21 mA/cm2 was achieved on the multihigh-index facet BiVO4 photoanode at 1.23 V versus reversible hydrogen electrode (RHE) in 0.1 M Na2SO4, which is about 200% improved over the normal BiVO4 photoanode (0.61 mA/cm2 at 1.23 V vs RHE). In addition, a negative shift of 300 mV onset potential for water oxidation was observed on the as-prepared BiVO4 photoanode (0.22 V vs RHE) relative to the normal BiVO4 photoanode (0.52 V vs RHE) in 0.1 M Na2SO4. Although the UV?vis absorbance property and water oxidation pathway not be changed, the charge-transfer and separation properties as well as the overall water oxidation kinetics on the multihigh-index facet BiVO4 film were boosted obviously. Theory calculations reveal that the adsorption of H2O molecules on BiVO4{121} and {132} high-index facets is energetically favorable for subsequent dissociation and oxidation relative to that on {010} and {110} low-index facets. Furthermore, the water oxidation limiting step on {121} and {132} high-index facets of BiVO4 is changed to the step of two protons reacting with (cid:129)O to form (cid:129)OOH species ((cid:129)O + H2O(l) + 2H+ + 2e? → (cid:129)OOH + 3H+ + 3e?), which is different from the limiting step on {010} and {110} low-index facets that corresponds to the dissociation of H2O to (cid:129)OH (2H2O(l) + (cid:129) → (cid:129)OH + H2O(l) + H+ + e?). In addition, the overpotential of water oxidation limiting step on BiVO4{121} and {132} high-index facets is lower than that on {010} and {110} low-index facets.
关键词： photoanode,BiVO4,high-index facets,water oxidation,photoelectrochemical
更新于2025-09-09 09:28:46
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Photocharged Fe <sub/>2</sub> TiO <sub/>5</sub> /Fe <sub/>2</sub> O <sub/>3</sub> Photoanode for Enhanced Photoelectrochemical Water Oxidation
摘要： Photocharging is a novel and effective photoanode treatment to improve the photoelectrochemical water splitting performance. Here a photocharged Fe2TiO5/Fe2O3 photoanode was prepared with a significantly increased photocurrent density. Furthermore, the photocharging effect could also be deactivated via a discharging treatment under dark conditions. By using X-ray absorption spectroscopy and electrochemical impedance spectroscopy, the photocharging effect was revealed to be the formation of Fe(IV) intermediates at the interface to accelerate the water oxidation kinetics. The results offer a detailed understanding on the mechanism of the photocharging effect in hematite, which may help for the design of highly efficient water splitting catalysts.
关键词： photoanode,Fe2TiO5/Fe2O3,water oxidation,photocharging,photoelectrochemical
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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A highly efficient NiFe nanoparticles decorated Si photoanode for photoelectrochemical water oxidation
摘要： n-Si is a narrow band gap semiconductor that has been demonstrated as an excellent photo-absorber material for photoelectrochemical (PEC) water splitting. Depositing a thin layer of Ni film on n-Si can form a Schottky junction at the interface, which offers a simple and useful route toward light-driven water oxidation. However, the relatively low catalytic activity of the Ni layer and the presence of interface states limits the application of this structure. Herein, we prepared a high performance NiFe nanoparticles decorated Si photoanode for the efficient solar driven water oxidation to H2. NiFe nanoparticles were dispersed on a Si substrate surface homogeneously to form an inhomogeneous metal-insulator-semiconductor (MIS) junction, which increased the photovoltage of photoanode. In addition, the oxide/oxyhydroxide layer on the deposited NiFe layer formed during the evaporation deposition acted as a highly efficient electrocatalyst, which also contributed to the high PEC performance of the photoanode. The photoanode covered with 2 nm NiFe film exhibited the best PEC performance with a low onset potential of 1.09 V vs. RHE (the potential required to reach the photocurrent of 1 mA/cm2), a high photocurrent of 25.2 mA/cm2 at 1.23 V vs. RHE, and a stable output over 50 h under AM 1.5G illumination due to the high performance inhomogeneous MIS junction and a thick oxide/oxyhydroxide catalytic shell formed on NiFe nanoparticle via an aging process.
关键词： photoelectrochemical water oxidation,oxide/oxyhydroxide layer,Si photoanode,NiFe nanoparticles,MIS junction
更新于2025-09-04 15:30:14
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A porous Ni-O/Ni/Si photoanode for stable and efficient photoelectrochemical water splitting
摘要： Excellent photoelectrochemical activity was demonstrated for an easily prepared porous Ni-O/Ni/Si photoanode with an onset potential of 0.93 VRHE, a photocurrent of 39.7 mA cm?2 at 1.23 VRHE, an energy conversion efficiency of 3.2% and a stability above 100 h.
关键词： stability,water splitting,porous Ni-O/Ni/Si photoanode,energy conversion efficiency,photoelectrochemical
更新于2025-09-04 15:30:14