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A novel electrochemical method for simultaneous measurement of real-time potentials and photocurrent of various photoelectrochemical systems
摘要： Two-electrode configuration is preferably used in practical application of various photoelectrochemical systems, such as green fuel production and cathodic protection. Photo electrodes are extendedly studied but the effects of the dark electrodes on overall performance of PEC systems are not experimentally figured out. To address this issue, herein, a novel electrochemical method achieving simultaneous measurement of photocurrent and real-time potential of the photo electrode and the dark electrode is proposed. With this method, the actual band positions and band bending of the photo electrode under photocurrent going through can be determined correctly. By investigating photoelectrochemical hydrogen production and cathodic protection with ZnO photo anodes, it is revealed that the amplitude of photocurrent is not solely determined by the number of light generated electrons on the photo electrode but also strongly affected by their consuming rate for electrochemical reactions on the dark electrode. These applications demonstrate the practicality, reliability and universality of the proposed method for comprehensive understanding the reactions of various photoelectrochemical systems and eventually for their better development.
关键词： Semiconducting materials,Artificial solar synthesis,Photoelectrochemical cathodic protection,Photocatalysis,Photoelectrochemical water splitting
更新于2025-09-19 17:15:36
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Ag-Functionalized CuWO <sub/>4</sub> /WO <sub/>3</sub> nanocomposites for solar water splitting
摘要： Ag-Functionalized CuWO4/WO3 heterostructures were successfully prepared via a polyvinyl pyrrolidone (PVP)-assisted sol–gel (PSG) route. Thin films prepared via electrophoretic deposition were used as photoanodes for photoelectrochemical (PEC) water splitting. Compared to pristine CuWO4 and WO3 films, a significant enhancement of the photocurrent (3–4 times) at the thermodynamic potential for oxygen evolution (0.62 V vs. Ag/AgCl, pH 7) was obtained for the Ag-functionalized CuWO4/WO3 photoanodes. The obtained enhancement is shown to be derived from a synergic contribution of heterostructure formation (CuWO4/WO3) and improvements of light utilization by Ag-induced surface plasmon resonance (SPR) effects. Accordingly, a photocurrent of 0.205 mA cm?2 at 0.62 V vs. Ag/AgCl under neutral conditions (without hole scavengers) under front-side simulated AM1.5G illumination was achieved. A detailed analysis of the obtained PEC data alongside performed impedance measurements suggests that charge separation is significantly improved for the prepared Ag-functionalized CuWO4/WO3 photoanodes. Our work offers beneficial insights to design new plasmonic metal/heterostructured nanocomposites for energy conversion applications.
关键词： nanocomposites,surface plasmon resonance,photoelectrochemical,CuWO4/WO3,solar water splitting,Ag-functionalized,heterostructures
更新于2025-09-19 17:15:36
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Hybridizing NiCo2O4 and amorphous NixCoy layered double hydroxides with remarkably improved activity towards the efficient overall water splitting
摘要： Overall water splitting is an attractive technology to produce clean hydrogen and oxygen. In this study, we constructed amorphous NixCoy layered double hydroxide (LDH) hybridized with three-dimensional NiCo2O4 to fabricate core-shell nanowire array on Ni foam (NiCo2O4@NixCoy LDH/NF) as highly efficient electrocatalyst for overall water electrolysis. By tuning the Ni/Co molar ratio in NixCoy LDH, extremely low overpotentials of 193 mV for oxygen evolution reaction (OER) and 115 mV for hydrogen evolution reaction (HER) at a current density of 10 mA cm?2 can be achieved for the NiCo2O4@Ni0.796Co LDH/NF. Detailed investigations verify that the hybrid structure can increase intrinsic activity of the NiCo2O4@Ni0.796Co LDH/NF and enhance the charge-transfer rate. Moreover, a strong electronic interaction between the heterogeneous elements Ni and Co at the interface of the NiCo2O4 and NixCoy LDH might ultimately influence the catalytic performance.
关键词： bifunctional electrocatalyst,nanowire arrays,amorphous material,layered double hydroxide,water splitting
更新于2025-09-19 17:15:36
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Hierarchical CoFe-Layered double hydroxide and g-C3N4 heterostructures with enhanced bifunctional photo/ electrocatalytic activity towards overall water splitting
摘要： To achieve sustainable and clean energy for the hydrogen economy, developing efficient earth-abundant and non-noble transition metal photo/electrocatalysts toward overall water splitting is highly desirable. In this work, layered double hydroxide (LDH)@g-C3N4 composites with hierarchical flower-like micro/nanosheets and high surface area have been synthesized by a solvothermal method. HRTEM images exhibit that the surface of g-C3N4 nanosheets is highly orientation with the main exposure of (002) plane. Compared with the pristine CoFe-LDH, the hierarchical nanocomposite presents an excellent and stable electrocatalytic performance in 1.0 M KOH, with a small Tafel slope of 58 mV/dec and an overpotential of about 275 mV at a current density of 10 mA/cm2. Simultaneously, CoFe-LDH@g-C3N4 exhibits an exceptional performance for the HER in 1.0 M KOH electrolyte, with the overpotential of 417 mV at a current density of 10 mA/cm2 and a small Tafel slope of 77 mV/dec. Therefore, this work not only accomplishes improved catalytic activity of the CoFe-LDH by the introduction of g-C3N4 nanosheets, but also provides an insight into the correlation between the hierarchical flower-like morphologies and photo/electrochemical catalytic activity for overall water splitting.
关键词： bifunctional activity,photo/electrocatalysts,hierarchical CoFe-LDH@g-C3N4,solvothermal method,overall water splitting
更新于2025-09-19 17:15:36
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AVALIA??O DO PAPEL DO óXIDO DE GRAFENO (GO) NA GERA??O FOTOCATALíTICA DE HIDROGêNIO EM SISTEMAS BINáRIOS (GO-CdS) E TERNáRIOS (Pt-GO-CdS)
摘要： EVALUATION OF THE GRAPHENE OXIDE (GO) ROLE IN THE PHOTOCATALYTIC GENERATION OF HYDROGEN IN BINARY (GO-CdS) AND TERNARY (Pt-GO-CdS) SYSTEMS. Water splitting is a promising process to produce hydrogen from friendly feedstock and solar energy. In this work we have evaluated binary (GO-CdS) and ternary (Pt-GO-CdS) hybrid photocatalysts for hydrogen production assisted by visible light irradiation. Cadmium sulfide and composites with GO were prepared by sonochemical and thermal methods. GO addition took place by different strategies: during the synthesis or by mechanical mixture. A variety of configurations was tested and the best performance in hydrogen production among all materials was the ternary photocatalyst named Pt(GO/CdSTT), whose hydrogen production rate was 651 μmol gcat-1 h-1. Such material was obtained by thermal method with GO addition during the synthesis. Additionally, the XRD and Raman analyses have confirmed the GO photoreduction during photocatalytic hydrogen evolution.
关键词： graphene,water splitting,cadmium sulfide,visible light,hydrogen,photocatalysis
更新于2025-09-19 17:15:36
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Hydrogen and Oxygen Evolution in a Membrane Photoreactor Using Suspended Nanosized Au/TiO2 and Au/CeO2
摘要： Photocatalysis combined with membrane technology could offer an enormous potential for power generation in a renewable and sustainable way. Herein, we describe the one-step hydrogen and oxygen evolution through a photocatalytic membrane reactor. Experimental tests were carried out by means of a two-compartment cell in which a modified Nafion membrane separated the oxygen and hydrogen evolution semi-cells, while iron ions permeating through the membrane acted as a redox mediator. Nanosized Au/TiO2 and Au/CeO2 were employed as suspended photocatalysts for hydrogen and oxygen generation, respectively. The influence of initial Fe3+ ion concentration, ranging from 5 to 20 mM, was investigated, and the best results in terms of hydrogen and oxygen evolution were registered by working with 5 mM Fe3+. The positive effect of gold on the overall water splitting was confirmed by comparing the photocatalytic results obtained with the modified/unmodified titania and ceria. Au-loading played a key role for controlling the photocatalytic activity, and the optimal percentage for hydrogen and oxygen generation was 0.25 wt%. Under irradiation with visible light, hydrogen and oxygen were produced in stoichiometric amounts. The crucial role of the couple Fe3+/Fe2+ and of the membrane on the performance of the overall photocatalytic system was found.
关键词： water splitting,photocatalytic membrane reactor,photocatalysis,Z-scheme
更新于2025-09-19 17:15:36
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Extending the ?-electron conjugation in 2D planar graphitic carbon nitride: Efficient charge separation for overall water splitting
摘要： We report the direct overall pure water splitting by visible light excited graphitic carbon nitride incorporated with conjugated aromatic rings without using sacrificial agents. We fabricated the modified graphitic carbon nitride polymer samples by copolymerization of melamine with 2,4,6-triaminopyrimidine and 1,3,5-triaminobenzene, containing a few-carbon (pyrimidine) to all-carbon (benzene) aromatic rings. Solid state 13C NMR shows that the core molecular skeleton of g-C3N4 remained intact even after the incorporation of benzene and pyrimidine aromatic rings into g-C3N4 chemical structure. Upon substitution of benzene aromatic ring in the place of triazine ring, the optical band gap energy of g-C3N4 is narrowed down from 2.8 eV to 2.1 eV with negative shifts of valence and conduction bands and due to the formation of defects like nitrogen vacancies. The DFT calculations predict that the benzene doped carbon nitride polymer has localized charge densities over valence band maxima and conduction band minima in different parts of heptazine rings, which assist in reducing the recombination rate of the charge carriers. The benzene ring incorporated carbon nitride photoelectrode shows higher photocurrent with lesser charge transfer resistance than the parent g-C3N4 and pyrimidine doped g-C3N4 polymers. This demonstrates the importance of the extended conjugation in g-C3N4 due to the presence of aromatic benzene rings. This is further corroborated by photoluminescence and electron paramagnetic resonance measurements. As a result, the benzene ring incorporated carbon nitride is more active than the pyrimidine ring incorporated carbon nitride for solar water splitting. The benzene ring incorporated carbon nitride polymer directly splits water and generates about 7 μmol h-1 of hydrogen with apparent quantum yield of 1.6% at 450 nm in the absence of sacrificial reagents, achieving turnover number of 1.6.
关键词： turnover number,benzene,DFT calculations,Carbon nitride,apparent quantum yield,charge separation,pyrimidine,water splitting
更新于2025-09-19 17:15:36
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New Understanding of Crystal Control and Facet Selectivity of Titanium Dioxide Ruling Photocatalytic Performance
摘要： Engineering crystals of titanium dioxide (TiO2) to expose with the most reactive facet has been proved to significantly improve the photocatalytic performance. While most of TiO2 with facets reported in the past were in a particle form, herein we directly grow TiO2 with arbitrarily tunable facets onto the transparent conductive substrate. This could reduce interparticle boundaries, and thus suppress charge recombination and facilitate more efficient charge transport compared to particle-assembled films. Combined systematic experimental and theoretical (Density Function Theory, DFT) studies reveal that fluoride ions (F-) and protons (H+) could play a synergistic role in controlling TiO2 crystals in the way that F- ions change the crystal phase of TiO2 to anatase with low-indexed facets, while H+ ions increase of {001}/{101} ratio. Moreover, the reductive and oxidative sites of facets are clearly elucidated by a selective photodeposition of noble metal and metal oxide. Different photocatalytic tests manifested that {001} facet, which is conventionally believed as the highest reactive facet, does not always show highest performance. On the other hand, the facets reactivity appeared to depend on the types of reactions (reduction or oxidation) and the co-existing synergy of facets. These findings would clarify the ambiguous understanding about the true factors controlling facets, the true order of reactivity of each facet that has still been controversial, and pave a way to improve both efficiency and selectivity of TiO2 in a wide variety of photocatalytic applications in the future.
关键词： Facet Control,CO2 Photoreduction,TiO2,Crystal Growth,PEC Water Splitting
更新于2025-09-19 17:15:36
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Enhanced Photoelectrochemical Performance of BiVO4 by a NiMoO4 Modification
摘要： In this work, porous BiVO4 thin films were deposited on the FTO glass through a spin-coating deposition method and their photoelectrochemical (PEC) properties were investigated. Further, the BiVO4 thin film was modified with a NiMoO4 thin layer for enhancing its PEC activity. It is demonstrated that the applied bias photo-to-current conversion efficiency is increased by 63% after a surface modification, which is ascribed to both the formation of a p–n junction and the suppressed carrier recombination rate by terms of the electrochemical impedance spectroscopy. Finally, a schematic band model is also proposed to clarify the charge carrier transfer mechanism which is responsible for the enhanced PEC performance.
关键词： photoelectrochemical,NiMoO4,BiVO4,water splitting
更新于2025-09-19 17:15:36
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Structure and Photocatalytic Activity of PdCrOx Cocatalyst on SrTiO3 for Overall Water Splitting
摘要： The mechanism of PdCrOx multi-component cocatalyst formation on SrTiO3 was investigated using transmission electron microscopy, X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy. The PdCrOx/SrTiO3 samples were synthesized by a photodeposition method under UV light irradiation (λ > 300 nm) for various time periods (0–5 h). The fine structure and valence state of the Pd species of PdCrOx nanoparticles were varied from Pd oxide to a mixture of metallic Pd and oxidized Pd species with an increase in the irradiation time. The overall water-splitting activity of PdCrOx was strongly dependent on the photoirradiation time during deposition. Although longer photoirradiation time during preparation did not influence the H2 evolution activity of PdCrOx/SrTiO3 from aqueous methanol solution, it was effective in suppressing the O2 photoreduction activity, which is one of the backward reactions during overall water splitting.
关键词： cocatalyst,semiconductor photocatalyst,water splitting
更新于2025-09-19 17:15:36