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Effect of Mo doping and NiFe-LDH cocatalyst on PEC water oxidation efficiency
摘要： The NiFe-layered double hydroxide (LDH) nanosheets were decorated on the surface of doped BiVO4 to structure an integrating photoanode for improving solar photoelectrochemical (PEC) water splitting efficiency, which is a dynamic research topic to solve the energy crisis and remit environmental pollution caused by fossil fuel combustion. The fabricated photoanode exhibits rapid response to visible light, enhances photocurrent density and shows significant cathodic shift compared to BiVO4. Moreover, the measured incident photon-to-current efficiency (IPCE) of the photoanode is comparable to that reported in the literature. The amount of evolution oxygen was measured and the faradaic efficiency produced oxygen was also obtained by comparing the theoretical calculation value. The enhancement is attributed to the increase of the carrier density, the effective separation of photogenerated electron-hole and consuming of the photogenerated holes accumulated at the electrode surface, which has been confirmed by electrochemical impedance spectra (EIS) and the intensity modulated photocurrent spectra (IMPS). The work may offer a promising method for designing a high efficiency and low-cost photoanode.
关键词： NiFe-layered double hydroxides.,BiVO4,Mo-doping,Photoelectrochemical water splitting
更新于2025-09-23 15:23:52
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Spatial dual-electric fields for highly enhanced the solar water splitting of TiO2 nanotube arrays
摘要： Efficient charge separation is essential for improving the photo-conversion efficiency in both photocatalytic and photoelectrochemical (PEC) water splitting. Herein, we have demonstrated the selective spatial-construction of Au nanolayer and SrTiO3 nanocubes on inner and outer surfaces of TiO2 nanotubes for enhancing the charge separation and PEC activity. More specifically, the outer SrTiO3 nanocubes with a spontaneous ferroelectric polarization could effectively engineer the electrical band bending of TiO2 nanotubes, facilitating hole transfer to the electrode/electrolyte interface for water oxidation. Meanwhile, the inner Au nanolayer with a favorable plasmonic electric-field induced by the visible light promote charge separation and rapid electron transfer to the counter electrode for hydrogen generation. Benefiting from the spatial dual-electric fields, this SrTiO3/TiO2/Au ternary-photoanode exhibits a significantly enhanced photocurrent density of 2.11 mA cm?2 at 1.23 V (vs. RHE), which is nearly 3.5 times higher than that of the pristine TiO2 nanotube arrays. Additionally, a low onset potential (~ 0.17 VRHE) for water oxidation as well as an excellent PEC stability has also been achieved. These demonstrations may provide a new strategy toward the rational construction of highly efficient PEC water splitting systems.
关键词： TiO2 nanotube,Water splitting,Plasmonic,Ferroelectric
更新于2025-09-23 15:23:52
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Metal–organic framework coated titanium dioxide nanorod array p–n heterojunction photoanode for solar water-splitting
摘要： This paper presents a p–n heterojunction photoanode based on a p-type porphyrin metal–organic framework (MOF) thin film and an n-type rutile titanium dioxide nanorod array for photoelectrochemical water splitting. The TiO2@MOF core–shell nanorod array is formed by coating an 8 nm thick MOF layer on a vertically aligned TiO2 nanorod array scaffold via a layer-by-layer self-assembly method. This vertically aligned core–shell nanorod array enables a long optical path length but a short path length for extraction of photogenerated minority charge carriers (holes) from TiO2 to the electrolyte. A p–n junction is formed between TiO2 and MOF, which improves the extraction of photogenerated electrons and holes out of the TiO2 nanorods. In addition, the MOF coating significantly improves the efficiency of charge injection at the photoanode/electrolyte interface. Introduction of Co(III) into the MOF layer further enhances the charge extraction in the photoanode and improves the charge injection efficiency. As a result, the photoelectrochemical cell with the TiO2@Co-MOF nanorod array photoanode exhibits a photocurrent density of 2.93 mA/cm2 at 1.23 V (vs. RHE), which is ~ 2.7 times the photocurrent achieved with bare TiO2 nanorod array under irradiation of an unfiltered 300 W Xe lamp with an output power density of 100 mW/cm2.
关键词： p–n junction,photoanode,titanium dioxide,metal-organic framework,water-splitting
更新于2025-09-23 15:23:52
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Energy diagram analysis of photoelectrochemical water splitting process
摘要： Photoelectrochemical (PEC) water splitting process is thoroughly revisited based on the energy diagram to elucidate the experimental observations. The TiO2 nanorod structure is studied as the model system for the photoanode of the PEC cell due to its stability in both acidic and basic solutions. The photocurrents with the external bias are examined under the various electrolytes of H2SO4, NaCl, and NaOH. The energy diagrams of the whole PEC system related to the water splitting process are interactively constructed in three-electrode configuration with the vacuum level as the common reference. Electrode potentials and photocurrents measured with the external bias in dark and under light are systematically correlated with the energy diagram of the PEC system. The pH dependent flat-band potential is explained by applying the pH dependent Helmholtz layer potential at the interface. In addition, the distribution of the applied potential in the PEC system during the water splitting process is understood by in-depth understanding of the energy band diagram.
关键词： band analysis,TiO2 nanorod,photoelectrochemical water splitting
更新于2025-09-23 15:23:52
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Fully Solar-Powered Uninterrupted Overall Water-Splitting Systems
摘要： Extensive research efforts have been recently devoted to the development of self-driven electrocatalytic water-splitting systems to generate clean hydrogen chemical fuels. Currently, self-driven electrocatalytic water-splitting devices are powered by solar cells, which operate intermittently, or by aqueous batteries, which deliver stored electric power, leading to high operating costs and environmental pollution. Thus, a fully solar-powered uninterrupted overall water-splitting system is greatly desirable. Here, the solar cells, stable output voltage of 1.75 V Ni–Zn batteries, and high efficiency zinc–nickel–cobalt phosphide electrocatalysts are successfully assembled together to create a 24 h overall water-splitting system. Specifically, the silicon-based solar cells enable the charging of aqueous Ni–Zn batteries for energy storage as well as providing sufficient energy for electrocatalysis throughout the day; in addition, the high-capacity Ni–Zn batteries offer a steady output voltage for overall water-splitting at night. Such an uninterrupted solar-to-hydrogen system opens up exciting opportunities for the development and applications of renewable energy.
关键词： uninterrupted,solar-powered,water-splitting system,aqueous rechargeable batteries
更新于2025-09-23 15:23:52
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Artificial Mn4Ca-cluster with Exchangeable Solvent Molecules Mimicking the Oxygen-Evolving Center in Photosynthesis
摘要： The natural Mn4Ca-cluster in photosystem II serves as a blueprint to develop artificial water-splitting catalysts in artificial photosynthesis. Although significant advances have recently been achieved, it remains great challenges to prepare robust artificial Mn4Ca-cluster to precisely mimic the structure and function of the biological catalyst in the laboratory. Here, we report the isolation and structural characterization of two Mn4CaO4-complexes from polar solvents acetonitrile or N, N-dimethylformamide, which closely mimics the two water molecules on calcium ion, as well as, the oxidation states of the four manganese ions and the main geometric structure of the natural Mn4Ca-cluster. These new artificial Mn4Ca-complexes provide important chemical clues to understand the structure and mechanism of its biological paragon.
关键词： heterometallic complexes,photosynthesis,bioinorganic chemistry,water splitting,manganese
更新于2025-09-23 15:23:52
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Electronic Structure and Room Temperature Ferromagnetism in Gd-doped Cerium Oxide Nanoparticles for Hydrogen Generation via Photocatalytic Water Splitting
摘要： Enhanced visible light photocatalytic activity of Gd-doped CeO2 nanoparticles (NPs) is experimentally demonstrated, whereas there are very few reports on this mechanism with rare earth doping. All-pure and Gd-doped CeO2 NPs are synthesized using a coprecipitation method and characterized using X-ray diffraction (XRD), absorption spectroscopy, surface-enhanced Raman Spectroscopy (SERS), X-ray photoelectron spectroscopy (XPS), and superconducting quantum interference device (SQUID). The effect of Gd-doping on properties of CeO2 is discussed along with defects and oxygen vacancies generation. The XRD confirms the incorporation of Gd3+ at the Ce3+/Ce4+ site by keeping the crystal structure same. The average particle size from transmission electron microscopy (TEM) images is in the range of 5–7 nm. The XPS spectra of Ce 3d, O 1s, and Gd 4d exhibits the formation of oxygen vacancies to maintain the charge neutrality when Ce4+ changes to Ce3+. The gradual increase in hydrogen production is observed with increasing Gd concentration. The observed results are in good correlation with the characterization results and a mechanism of water splitting is proposed on the basis of analyses. The absorption spectra reveal optical band gap (2.5–2.7 eV) of samples, showing band gap narrowing leads to desired optical absorbance and photoactivity of NPs.
关键词： water splitting,hydrogen generation,SERS,XPS
更新于2025-09-23 15:23:52
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Construction of flower-like MoS2/Ag2S/Ag Z-scheme photocatalysts with enhanced visible-light photocatalytic activity for water purification
摘要： Flower-like MoS2/Ag2S/Ag nanocomposites have been elaborately designed and synthesized successfully for the first time. The prepared MoS2/Ag2S/Ag nanocomposites as a novel photocatalysts present effective photocatalytic performance for the photodegradation of congo red (CR), tetracycline hydrochloride (TC-HCl) and disinfection for Pseudomonas aeruginosa (P. aeruginosa). For the photodegradation of TC-HCl, the effect of the pH of the initial solution and photocatalysts dosage was investigated. Furthermore, intermediates of TC-HCl degradation were verified by GC–MS analysis and the possible pathway of the photodegradation was also proposed. The electron paramagnetic resonance (EPR) technique and trapping experiments verified the electron transport path is Z-scheme system (PS-C-PS). Among them, Ag as an electron mediator enhanced the electron transmission rate and accelerated the separation efficiency of photogenerated carriers.
关键词： MoS2/Ag2S/Ag,Photocatalytic,Tetracycline hydrochloride,Water disinfection,Z-scheme
更新于2025-09-23 15:23:52
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Introduction of oxygen vacancies into hematite in local reducing atmosphere for solar water oxidation
摘要： Sn Doping and creation of oxygen vacancies have been adopted universally to overcome the poor electric conductivity and unfavorable hole diffusion length of α-Fe2O3 photoanodes. Generally, Sn doping is realized via longitudinal migration of tin element from FTO (fluorine-doped tin oxide) substrates into α-Fe2O3 at high temperature. To introduce oxygen vacancies along with Sn into hematite for further promoting its electric conductivity, we have created a local reducing atmosphere via partial oxidation of graphite while doping hematite with Sn. The donor density of the resultant Fe2O3 photoanode annealed on graphite (G-Fe2O3) at 770 °C for 20 min is increased to ～1.7 times that of the counterpart annealed on SiO2 powders (S-Fe2O3), indicating that the electric conductivity of hematite is improved after introduction of oxygen vacancies. Moreover, oxygen vacancies have been demonstrated to significantly reduce the charge transfer resistance of Sn doped hematite. Consequently, the photocurrent density of G-Fe2O3 is enhanced remarkably (～70%) compared with S-Fe2O3. However, the improvement in photocurrent density due to oxygen vacancies becomes less significant when more Sn is doped into hematite. The strategy for creation of oxygen vacancies reported here can be extended to other photoanodes for better understanding the effect of oxygen vacancies on PEC performance.
关键词： Oxygen vacancies,Sn doping,Solar water oxidation,Hematite
更新于2025-09-23 15:23:52
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Enhanced solar light driven activity of p-n heterojunction for water oxidation induced by deposition of Cu2O on Bi2O3 microplates
摘要： As an important half reaction in solar-driven water splitting, it is more challenging to develop low-cost and highly efficient photocatalysts for water oxidation. The enhancement of sunlight harvesting and inhibition of charge-carrier recombination are keys to fabricating efficient semiconductor-based photocatalysts for energy conversion from solar light to chemicals. Herein, we reported highly dispersive Cu2O/Bi2O3 composites prepared by a facile and benign synthetic route, where n-type Bi2O3 microplates and nano-sized p-type Cu2O were coupled together to construct heterojunctions to improve the transportation efficiency of photoinduced charge carriers, benefited from the intimate interactions at the interfaces between Bi2O3 and Cu2O. The electrochemical properties of charge-transportation and population of charge carriers were investigated in the heterojunctions. The hybrid materials exhibit both enhanced photocatalytic performances in water oxidation and photodegradation of dyes compared with sole Bi2O3 or Cu2O under artificial solar light irradiation. The initial O2 evolution rate of the heterojunction system is 1.4- and 8-fold higher than the pure Bi2O3 and Cu2O, respectively. This study provides new protocols for synthesizing novel hybrid materials with insights into heterojunction-based photocatalysis for green energy production and wastewater purification.
关键词： Nanocomposite,Water oxidation,Photocatalysis,Heterojunction,Wastewater purification
更新于2025-09-23 15:23:52