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Insight into Reinforced Photocatalytic Activity of CNT-TiO <sub/>2</sub> nanocomposite for CO <sub/>2</sub> Reduction and Water Splitting
摘要： Using titanium dioxide (TiO2) and its modified forms for photocatalytic reduction of CO2 reduction and production of hydrogen are promising routes for providing solutions to the world energy demand in the foreseeable future. Here, we report the synthesis of a series of efficient, stable TiO2 nanoparticles modified with multi-walled carbon nanotubes (CNT) via a simple, combined sonothermal method followed by a hydrothermal treatment. In comparison to bare TiO2, the synthesized CNT-TiO2 photocatalysts showed improved photocatalytic activities for CO2 reduction under UVA as well as under visible light; and water (H2O) splitting under visible light at ambient temperature and pressure. The 2.0CNT-TiO2 has performed the best for methanol, hydrogen and formic acid production from the reduction of CO2 with yield rates of 2360.0, 3246.1 and 68.5 μmol g-1 h-1 under UVA, respectively. Its potential was further tested under visible light for methanol production, 1520.0 μmol g-1 h-1. Also, the highest rate of hydrogen yield from water splitting was 69.41 μmol g-1 h-1 with 2.0CNT-TiO2 under visible light at pH 2. The primary photocatalytic reactions of CNT-TiO2 composites and their intimate structure were studied computationally. It was demonstrated that the binding of CNT to TiO2 nanoparticles are preferable at (101) surfaces compared to (001) facets. Interaction of CNT with TiO2 results in common orbitals within TiO2 band gap that enables visible light excitation of the CNT-TiO2 composites can lead to charge transfer between TiO2 and CNT; while UV light excitation can result in charge transfer in any direction, from CNT to TiO2 and from TiO2 to CNT. The latter process is operative in the presence of sacrificial electron donor TEOA.
关键词： photocatalytic reduction,CO2 reduction,UVA light,water splitting,visible light,CNT-TiO2 nanocomposite,hydrogen production
更新于2025-09-09 09:28:46
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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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Ion Beam Defect Engineering on ReS <sub/>2</sub> /Si Photocathode with Significantly Enhanced Hydrogen Evolution Reaction
摘要： Loading 2D layered transition metal dichalcogenides (TMDs) on p-type silicon photocathode is suitable for hydrogen production in solar-driven photoelectrochemical (PEC) water splitting. Similarly, various nanostructured TMDs exposing more active sites are widely explored for improving the PEC performances of composite photoelectrodes. Here, defect engineering using a controllable argon ion beam bombardment is presented on ReS2/Si photocathode. The atomic vacancy defects are introduced on the 2D ReS2 to realize high-density active sites, which significantly enhance the solar-driven hydrogen evolution reaction performance of ReS2/Si photocathode. The highest photocurrent density of 18.5 mA cm?2 (at 0 V vs reversible hydrogen electrode) is achieved, under a simulated sun irradiation.
关键词： ion beam bombardment,defect engineering,photocathodes,photoelectrochemical water splitting,ReS2
更新于2025-09-09 09:28:46
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Interfacial Scaffolding Preparation of Hierarchical PBA-Based Derivative Electrocatalysts for Efficient Water Splitting
摘要： The development of highly efficient and durable electrocatalysts is crucial for overall water splitting. Herein, the in situ scaffolding formation of 3D Prussian blue analogues (PBAs) on a variety of 2D or 1D metal hydroxides/oxides to fabricate hierarchical nanostructures is first demonstrated. Typically, cobalt hydroxide or oxide nanoarrays are used as the precursor and structural oriented template for the subsequent growth of 3D PBA nanocubes. The mechanism study reveals that the interfacial scaffolding process can be reversibly controlled via the in situ ion exchange process with adjusting coordination ions. Thus, the facile, versatile strategy can extend to successfully fabricate a variety of hierarchical PBA-based nanostructures including on cobalt fluoride hydroxide, copper hydroxide, monometal or bimetal nickel–cobalt hydroxides, cobalt oxide, and manganese oxide nanosheets with structural tailor-ability and chemical diversity. More interestingly, the metal nitride derivatives obtained via controlled calcination process exhibit good electrocatalytic activity for water splitting with low overpotentials, and remarkable durability for 1200 h, thanks to the superior intrinsic activity of bimetal nature and the scrupulous hierarchical structure. This versatile strategy provides a paradigm for rational design of PBA-based functional nanomaterials, which is highly promising in energy conversion, storage, and electrocatalytic fields.
关键词： oxygen evolution reaction,water splitting,Prussian blue analogue,electrocatalysis,hydrogen evolution reaction
更新于2025-09-09 09:28:46
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Photoelectrochemical activity of Ag loaded TiO2 nanotube arrays produced by sequential chemical bath deposition for water splitting
摘要： We report on remarkable improvement of photoelectrochemical (PEC) properties of TiO2 nanotubes by loading of Ag nanoparticles into them. The silver nanoparticles were loaded on the nanotubes by sequential chemical bath deposition (S-CBD) with different number of deposition cycles. Various characterizations including field emission scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis (EDX), all confirm that the silver nanoparticles were deposited inside and outside of TiO2 nanotubes. In addition, the PEC properties of the samples were investigated using linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The PEC analyses clearly show that the photoelectrochemical activity of the Ag-loaded samples are considerably higher than the bare TiO2 nanotubes (about 3 times). This mostly originates from the improvement of light absorption due to the plasmonic effects in addition to better separation and transport of electron–hole pairs in the Ag-loaded samples relative to the bare TiO2 nanotubes. All results indicate that the maximum efficiency were obtained for the 8-cycle of S-CBD Ag-loading on the bare TiO2 nanotubes.
关键词： TiO2 nanotubes,sequential chemical bath deposition,water splitting,photoelectrochemical,Ag nanoparticles
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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Graphitic Carbon Nitride Impregnated Niobium Oxide (g-C <sub/>3</sub> N <sub/>4</sub> /Nb <sub/>2</sub> O <sub/>5</sub> ) Type (II) Heterojunctions and Its Synergetic Solar-Driven Hydrogen Generation
摘要： Graphitic carbon nitride (g-C3N4) based catalysts are evolving in energy harvesting applications due to their robustness, nontoxicity, and most important photocatalytic efficiencies. In this work, we successfully engineered g-C3N4/Nb2O5 type (II) heterojunction via pulse sonochemical technique based on opposite charge-induced hetero-aggregation on the surface. The agglomerated spherical Nb2O5 nanoparticles (NPs) having diameter 30-40 nm observed on the lamellar surface of g-C3N4 in FESEM images. The XRD and XPS analysis confirm the orthorhombic phase and formation of the g-C3N4/Nb2O5 heterostructure. The FTIR spectra of g-C3N4/Nb2O5 show characteristic poly s-triazine bands from 1250 to 1650 cm-1. Moreover, g-C3N4/Nb2O5 exhibited the lower bandgap value of 2.82 eV as compared to Nb2O5 (3.25eV) with significant redshift and enhance visible light absorption. The Mott-Schottky (MS) analysis confirms the formation of heterojunction between g-C3N4 and Nb2O5, with significant band shifting towards lower hydrogen evolution reaction (HER) potential. The g-C3N4/Nb2O5 heterojunctions showed many folds enhanced photocurrent response from photoelectrochemical (PEC) water splitting, and the value reached to – 0.17 mA/cm2 with good stability and insignificant dark photocurrent at 1.0 V vs RHE. The electrochemical impedance spectroscopic (EIS) measurements further elucidate the suppression of photogenerated electrons/holes as the radius of the semicircle significantly decreased in case of heterojunction formation. The enhanced photocatalytic hydrogen generation by the heterostructures could be attributed to the effective formation of heterojunctions between the g-C3N4 and Nb2O5 semiconductors, causing the migration of the photogenerated electrons and holes, hence increasing their lifetimes.
关键词： Pulse Sonication,PEC Water Splitting,g-C3N4,Photocurrent density,Nb2O5 NPs
更新于2025-09-09 09:28:46
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Sb <sub/>2</sub> O <sub/>3</sub> /Sb <sub/>2</sub> S <sub/>3</sub> Heterojunction Composite Thin Film Photoanode Prepared via Chemical Bath Deposition and Post-Sulfidation
摘要： Novel visible-light-driven Sb2O3/Sb2S3 photoelectrodes were synthesized via chemical bath deposition and post-sul?dation. An enhanced photocurrent density of 0.35 mA/cm2 at 1.23 V vs. RHE under simulated sunlight was achieved, compared to 0.008 mA/cm2 at 1.23 V vs. RHE for pure Sb2O3. The great improvement in the photoelectrochemical (PEC) performance bene?ts from the enhanced light absorbance and charge transfer ef?ciency attributable to the combination of Sb2S3. The Sb2O3/Sb2S3 heterojunction strategy shows potential for visible-light-driven photoelectrochemical water splitting.
关键词： heterojunction,photoelectrochemical,Sb2O3/Sb2S3,visible-light-driven,water splitting
更新于2025-09-09 09:28:46
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Metal oxide/(oxy)hydroxide overlayers as hole collectors and oxygen evolution catalysts on water splitting photoanodes
摘要： Solar-water-splitting provides a mechanism to convert and store solar energy in the form of stable chemical bonds. Water-splitting systems often include semiconductor photoanodes, such as n-Fe2O3 and n-BiVO4, which use photogenerated holes to oxidize water. These photoanodes often exhibit improved performance when coated with metal-oxide/(oxy)hydroxide overlayers that are catalytic for the water oxidation reaction. The mechanism for this improvement, however, remains a controversial topic. This is, in part, due to a lack of experimental techniques that are able to directly track the flow of photogenerated holes in such multicomponent systems. In this Perspective we illustrate how this issue can be addressed by using a second working electrode to make direct current/voltage measurements on the catalytic overlayer during operation in a photoelectrochemical cell. We discuss examples where the second working electrode is a thin metallic film deposited on the catalyst layer, as well as where it is the tip of a conducting atomic-force-microscopy probe. In applying these techniques to multiple semiconductors (Fe2O3, BiVO4, Si) paired with various metal-(oxy)hydroxide overlayers (e.g. Ni(Fe)OxHy and CoOxHy), we found in all cases investigated that the overlayers collect photogenerated holes from the semiconductor, charging to potentials sufficient to drive water oxidation. The overlayers studied thus form charge-separating heterojunctions with the semiconductor as well as serve as water-oxidation catalysts.
关键词： solar-water-splitting,water oxidation reaction,semiconductor photoanodes,photoelectrochemical cell,metal-oxide/(oxy)hydroxide overlayers
更新于2025-09-04 15:30:14
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Switching on efficient photocatalytic water oxidation reactions over CaNbO2N by Mg modifications under visible light illumination
摘要： In spite of a strong visible light absorbance as far as 600 nm, CaNbO2N generally exhibits poor photocatalytic activity under normal conditions because of various structural defects and poor charge mobility. In this work, we have synthesized a series of Mg-modified CaNbO2N, i.e. CaNb1-xMgxO2+yN1-y (0 ≤ x ≤ 0.2), and performed a detailed investigation on their crystal structures, optical absorption and other physicochemical properties. Our results show that there is a slight shrinkage of the unit cell and a blue-shift of absorption edges upon Mg incorporation into CaNbO2N. The nitrogen contents as well as defects levels can be effectively tuned by altering the content of Mg. More strikingly, photocatalytic oxygen productions are much improved after Mg modifications under visible light irradiation (λ ≥ 420 nm). An average oxygen production rate as much as ~126.8 umol h?1 and an apparent quantum efficiency as high as ~3.4 % at 420 ± 20 nm is achieved for CaNb0.9Mg0.1O2+yN1-y (x = 0.1). These improvements probably stem from a substantial decrease of Nb4+ defects in CaNbO2N as well as slight positive shift of valence band maximum (VBM) after Mg modifications. Meanwhile, photoelectrochemical analysis suggests charge migration is somewhat enhanced in response to Mg modifications.
关键词： water oxidation,CaNbO2N,photocatalyst,water splitting,Mg modification
更新于2025-09-04 15:30:14