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Synthesis of non-noble metal nickel doped sulfide solid solution for improved photocatalytic performance
摘要： Bimetallic Sul?des, a series of versatile catalysts, are still hampered from putting into practical application due to the issue of the recombination of photogenerated charges. In this work, in order to enhance the light harvesting ability as well as ameliorate the separation and transportation of photo-induced charges at the same time, Ni ion was adopted to modify Zn0.5Cd0.5S catalyst. The subsequent photocatalytic water splitting tests showed that the H2 evolution rate over Ni doped Zn0.5Cd0.5S was 6 times higher than that achieved on the prestine Zn0.5Cd0.5S, indicating a signi?cant enhancement in catalytic activity. Furthermore, the selective oxidation of benzyl alcohol was also performed by the as-prepared catalysts under visible light irradiation. When 1% Ni ions were doped in Zn0.5Cd0.5S solid solution, the yield of product benzaldehyde was increased from 70% to 92%. The photoelectrochemical test suggests that the improved photocatalytic performance is presumably ascribed to the e?cient separation of photo-generated carriers. Additionally, DOS calculation con?rms the contribution of the improved light harvesting ability of Ni-doped Zn0.5Cd0.5S in the photocatalytic reaction. In all, this work presents that doping Ni into ZnS/CdS solid solution is a very useful technique to improve photocatalytic activity for two typical photocatalytic reactions-the H2 evolution and alcohol selective oxidation reaction.
关键词： Photocatalyst,Metal doping,Selective oxidation,Hydrogen evolution
更新于2025-09-23 15:22:29
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Liquid exfoliation of g-C3N4 nanosheets to construct 2D-2D MoS2/g-C3N4 photocatalyst for enhanced photocatalytic H2 production activity
摘要： Although graphitic carbon nitride (g-C3N4) is an attractive photocatalyst for solar H2 generation, the preparation of g-C3N4 nanosheets via a “green” and simple method as well as the construction of highly-efficient g-C3N4-based photocatalysts are still challenges. In this study, g-C3N4 nanosheets prepared by a simple probe sonication assisted liquid exfoliation method were used to construct 2D-2D MoS2/g-C3N4 photocatalyst for photocatalytic H2 production. The 2D-2D MoS2/g-C3N4 photocatalyst containing 0.75% MoS2 showed the highest H2 evolution rate of 1155 μmol·h-1·g-1 with an apparent quantum yield of 6.8% at 420 nm monochromatic light, which is much higher than that of the optimized 0D-2D Pt/g-C3N4 photocatalyst. The high photocatalytic H2 production activity of 2D-2D MoS2/g-C3N4 photocatalyst can be attributed to the large surface area and the formed 2D interfaces between MoS2 and g-C3N4 nanosheets. As demonstrated by photoluminescence quenching and time-resolved fluorescence decay studies, the 2D interfaces can accelerate the photoinduced charge transfer, resulting in the high photocatalytic H2 production performance. This study provides a new strategy in developing highly-efficient g-C3N4-based photocatalysts for H2 production via using 2D nanojunction as a bridge to promote the photoinduced charge separation and transfer.
关键词： Hydrogen generation,Molybdenum disulfide,Graphitic carbon nitride,Photocatalysis,2D photocatalyst
更新于2025-09-23 15:22:29
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Calculations of adsorption energies, coadsorptions, and diffusion barriers of H atoms, and the H <sub/>2</sub> formation on a nanographene surface (coronene)
摘要： Adsorption and diffusion of ortho, meta, and para cis hydrogen dimers, on central and edge rings of coronene (nanographene), were studied by using the DFT-D method, considering different multiplicities. Calculated values of adsorption energy, coadsorption energy, diffusion barriers, and reaction barriers for the H2 formation (Langmuir-Hinshelwood (LH) mechanism) were evaluated for ortho and para locations. The adsorption of an H atom increases the adsorption energy of another hydrogen (coadsorption). The most stable dimers are those where an H is adsorbed on hydrogenated-edge sites. Dimers with multiplicity M = 1, with H separated by an odd number of bonds, have higher coadsorption energies (higher diffusion barriers) than those where the separation is by an even number. The H2 formation is more feasible on edge-edge and edge-center sites; however, on ortho hydrogenated-edge sites, it is not energetically favored. For M = 3, H2 formation is not observed because desorption of H occurs.
关键词： H2 formation,interstellar media catalysis,nanographene,coronene,hydrogen diffusion
更新于2025-09-23 15:22:29
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Prevent hydrogen damage in α-Cr2O3/α-Fe2O3 (0?0?0?1) interface
摘要： By means of first-principles calculations based on the density-functional theory, we investigate the vacancy trappings prevent hydrogen damage in two dimension α-Cr2O3/α-Fe2O3 (0 0 0 1) interface structure. Our calculations show that H atoms prefer to occupy the unoccupied O atoms octahedral interstitial site (Osite) in the center of the interface structure without vacancy defect, weakening the cleavage strength of Fe and O atoms and decreasing the work function and stability of interface structure. To prevent hydrogen damage in this interface structure, we model three Fe, Cr and O vacancy defects in this interface structure, respectively. Fe and Cr vacancy defects with lower H binding energy and higher work function, are better hydrogen trappings compared to O vacancy. These results confirm the Fe and Cr vacancy defects are effective hydrogen trappings to prevent hydrogen damage for passive film of steel, which has significant practical implications.
关键词： Interface structure,Fe vacancy,Hydrogen trapping,Work function
更新于2025-09-23 15:22:29
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Strengthened spatial charge separation over Z-scheme heterojunction photocatalyst for efficient photocatalytic H2 evolution
摘要： Graphitic carbon nitride (g-C3N4) is a very promising earth abundant and visible light response photocatalyst for H2 production. Fabricating novel nanostructure or combining with other semiconductors have been attempted to further enhance its activity. α-FeOOH, due to its structures greatly facilitating electrolyte transport, has been widely used as an excellent OER cocatalyst assisting the PEC water splitting process. However, to the best of our knowledge, it has not been attempted in photocatalytic H2 generation. Herein, g-C3N4 modi?ed with β-FeOOH was designed for the ?rst time for photocatalytic H2 production. It showed H2 production rate as 2.02 mmol·h?1·g?1, which was almost 6 times of pure g-C3N4. The signi?cantly promoted catalytic activity was ascribed to the greatly enhanced charge separation e?ciency by forming spatial separated reservoirs of photo activated electrons and holes in the Z-scheme heterojunction, corresponding to the conduction band of g-C3N4 and the valence band of β-FeOOH, respectively. Our work should be valuable for fabricating visible-light response heterojunction based photocatalysts with better photocatalytic performance.
关键词： Hydrogen evolution,β-FeOOH,Graphitic carbon nitride,Photocatalysis,Heterojunction
更新于2025-09-23 15:22:29
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Introduction of Nitrogen Defects into a Graphitic Carbon Nitride Framework by Selenium Vapor Treatment for Enhanced Photocatalytic Hydrogen Production
摘要： Graphitic carbon nitride (g-C3N4) is a metal-free semiconductor photocatalyst that has attracted significant attention due to its promising application in photocatalytic hydrogen production. However, pristine g-C3N4 suffers from a high recombination rate of photo-generated charge carriers and also has a limited visible-light absorption range, resulting in low photocatalytic activity. Herein, we report on the preparation and testing of a g-C3N4 photocatalyst with tunable nitrogen defects that delivered improved photocatalytic activity. The nitrogen defects were gradually introduced into the g-C3N4 framework by a selenium vapor treatment of pure g-C3N4, which resulted in improved, stable catalytic activity for photocatalytic hydrogen production. Based on the experimental results and DFT calculations, we proposed that the enhanced photoactivity is attributed to the defect state (DS) formed by the nitrogen vacancy (VN) in the unit cell of g-C3N4 and a small widening of visible light absorption. This nitrogen-based photocatalyst with nitrogen deficiencies was found to deliver an average hydrogen generation rate of 1.16 mmolg-1h-1 at room temperature (25 oC), which was 3.4 times greater than pristine g-C3N4. This process of introducing nitrogen defects into the graphitic carbon provides a promising way for enhancing the photocatalytic activity of g-C3N4-based materials for hydrogen production.
关键词： nitrogen vacancies,photocatalytic hydrogen production,g-C3N4,bandgap
更新于2025-09-23 15:22:29
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ZnO/CdS/PbS nanotube arrays with multi-heterojunctions for efficient visible-light-driven photoelectrochemical hydrogen evolution
摘要： High performance, low cost and sustainable photocatalytic evolution of hydrogen is a promising energy supply alternative for modern society to resolve the depletion crisis of fossil fuel. The design of multi-heterojunction visible-light photocatalysts combined with electrochemical means is considered one of the most attractive options in recent years. In this work, a photoanode composed of top-opened ZnO/CdS/PbS nanotube arrays (ZnO/CdS/PbS ONTs) with multi-heterojunctions was synthesized via a three-step process, i.e. hydrothermal treatment, chemical bath deposition and successive ionic layer adsorption reaction (SILAR). This as-prepared photoanode exhibited remarkable photoelectrochemical activity under visible light irradiation. The photocurrent density and photoelectrochemical hydrogen evolution efficiency of the optimized ZnO/CdS/PbS ONTs reached up to 14.2 mA cm-2 and 5.5 mL cm-2 h-1 at 0.0 V vs. Ag/AgCl, respectively. The efficiency was 3.1 times that of top-closed ZnO/CdS nanotubes (1.8 mL cm-2 h-1). The experimental results suggest that the high photoelectrochemical activity can be ascribed to the inherent advantages of the structural and successive energy level relays design: on the one hand, the top-opened nanotube structure significantly enlarges surface area of the nanostructure, which facilitates efficient light absorption and rapid mass transport; on the other hand, the well-matched band energy edge of the multi-heterojunction interfaces literally build efficient electron highways to deliver electrons to reaction sites and reduce the recombination of photogenerated charge carriers.
关键词： CdS,visible light,multi-heterojunction,ZnO,photoelectrochemical hydrogen evolution,PbS
更新于2025-09-23 15:22:29
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In situ electrochemical reduction assisted assembly of a graphene-gold nanoparticles@polyoxometalate nanocomposite film and its high response current for detection of hydrogen peroxide
摘要： The nanocomposite film including polyoxometalate (POM) cluster K28Li5H7P8W48O184·92H2O (P8W48), reduced graphene oxide (rGO) and Au nanoparticles (Au NPs) was successfully fabricated by electrochemical reduction assisted technique. This synthesis was novel, convenient, and environmentally friendly. Moreover, the time of fabricating process was greatly shorten to about 1 hour comparing to that of the traditional method of layer by layer (LbL) self-assembly. The reduced P8W48 was served as reducing agent, stabilizer and bridging molecules simultaneously in the composite film. The structure of the composite material was verified by comprehensive characterization using scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The investigation of the electrocatalysis for H2O2 showed that the {PEI/rGO}-Au@P8W48 modified electrode has high catalytic activity, good sensitivity, good selectivity, low detection limit and fast response. In addition, the result indicated that the electrocatalytic activity of the electrode with Au NPs was better than that of the electrode without Au NPs. The enhanced catalytic property was attributed to the synergistic effect of the rGO, P8W48 and Au NPs.
关键词： graphene,hydrogen peroxide,Au nanoparticles,electrocatalysis,polyoxometalates
更新于2025-09-23 15:22:29
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Nanoscale Fluorescent Metal?Organic Framework Composites as a Logic Platform for Potential Diagnosis of Asthma
摘要： Asthma is a common chronic disorder, and the decreased hydrogen sulfide (H2S) production in the lung has been considered as an early detection biomarker for asthma. However, the detection of H2S in biological systems remains a challenge; because it requires the designed sensors to have the following features: nanoscale size, good biocompatibility, real-time detection, high selectivity/sensitivity, and good water stability. Here, we propose the potential of using nanoscale fluorescent metal?organic framework (MOF) composites Eu3+/Ag+@UiO-66-(COOH)2 (hereafter denoted as EAUC) as a logic platform for tentative diagnosis of asthma by detecting the biomarker H2S. This INHIBIT logic gate based on Eu3+@UiO-66-(COOH)2 (EUC) can be produced by choosing Ag+ and H2S as inputs and by monitoring the fluorescent signal (I615) as an output. Our fluorescent studies indicate that the EAUC exhibits excellent selectivity, extreme sensitivity (limit of detection: 23.53 μM), and real-time in situ detection of H2S. Further, MTT analysis in PC12 cells shows that the EAUC possesses low cytotoxicity and favourable biocompatibility that are suitable for the detection of biomarker H2S in vivo, as demonstrated by the successful detection of spiked H2S in the diluted serum samples. This work represents the possibility of using MOF-based logic platform for tentative diagnosis of asthma in clinical medicine.
关键词： metal?organic frameworks,logic gate,asthma,chemical sensing,hydrogen sulfide
更新于2025-09-23 15:22:29
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Kinetic effects and oxidation pathways of sacrificial electron donors on the example of the photocatalytic reduction of molecular oxygen to hydrogen peroxide over illuminated titanium dioxide
摘要： Sacrificial electron donors are frequently used in photocatalytic reactions to enhance the performance of the reaction, typically short-chain alcohols as well as their respective aldehydes and acids are used. This study focuses on the differences between the individual electron donors regarding their oxidation rates, mechanistic pathways, the influence of the intermediates and their direct impact on the H2O2 generation. The individual H2O2 formation rates of 16 different electron donors, photonic and faradaic efficiencies for H2O2 production are carefully discussed. Furthermore, a new multi-reaction pathway for t-butanol oxidation is postulated and critically examined.
关键词： Alcohol oxidation,Reaction kinetics,Reaction pathway,Hydrogen peroxide,Photocatalysis,Sacrificial electron donors
更新于2025-09-23 15:22:29