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Single Nickel Atoms Anchored on Nitrogen-Doped Graphene as a Highly Active Co-Catalyst for Photocatalytic H2 Evolution
摘要： Earth abundant nickel is a typical non-noble-metal cocatalyst used for photocatalytic hydrogen evolution (PHE). Ni nanoparticles, however, tend to aggregate during the hydrogen production process, significantly lowering their PHE activity. In this research, we report single nickel atoms anchored on nitrogen-doped graphene (Ni-NG) as a cocatalyst for PHE. We have demonstrated that Ni-NG is a robust and highly active cocatalyst for PHE from water. With only 0.0013 wt.% of Ni loading, the PHE activity of composite Ni-NG/CdS photocatalyst is 3.4 times greater than that of NG/CdS. The quantum efficiency of Ni-NG/CdS for PHE reaches 48.2% at 420 nm, one of the highest efficiencies for non-noble-metal based cocatalysts reported in literature. Photoluminescence spectral analyses and electrochemical examinations have indicated that Ni-NG coupled to CdS can serve not only as an electron storage medium to suppress electron-hole recombination, but also as an active catalyst for proton reduction reaction. Density functional theory calculation shows that the high activity of Ni-NG/CdS composite results from the single Ni atoms trapped in NG vacancies, which significantly reduces the activation energy barrier of the hydrogen evolution reaction. This approach may be valuable for developing robust and highly active noble-metal free cocatalysts for solar hydrogen production.
关键词： Non-noble Metal Cocatalyst,CdS,Photocatalytic Hydrogen Evolution,Nitrogen-Doped Graphene,Single Ni Atom Catalysts
更新于2025-09-23 15:21:21
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Monolayer Attachment of Metallic MoS <sub/>2</sub> on Restacked Titania Nanosheets for Efficient Photocatalytic Hydrogen Generation
摘要： Monolayer attachment of metallic MoS2 (1T) on restacked titania (Ti0.87O2 0.52?) nanosheets was attained via a facile two-step flocculation process of their colloidal suspensions with the aid of the difference in critical H+ concentrations required for inducing flocculation of the respective nanosheets. The process produced porous flaky aggregates of restacked Ti0.87O2 0.52? nanosheets covered with monolayer MoS2, which serves as the electron collector and provides abundant catalytically active sites for proton reduction reaction. The MoS2-modified restacked-Ti0.87O2 0.52? nanosheets showed a remarkably high photocatalytic efficiency for hydrogen generation (1.2 mmol h-1 g-1), being superior to those of the restacked Ti0.87O2 0.52? nanosheets and P25-TiO2 nanoparticles conventionally modified with MoS2 (0.38, and 0.4 mmol h-1 g-1, respectively). The extensive molecular-level interfacial coupling of Ti0.87O2 0.52?/MoS2 nanosheets facilitates efficient charge separation and fast electron transfer, resulting in the significantly enhanced photocatalytic activity.
关键词： 2D heterointerface,photocatalysis,hydrogen evolution,two-step flocculation process,monolayer co-catalyst
更新于2025-09-23 15:21:21
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Bimetallic PtNi/g-C3N4 nanotubes with enhanced photocatalytic activity for H2 evolution under visible light irradiation
摘要： Bimetallic PtNi-decorated graphitic carbon nitride (g-C3N4) nanotubes were prepared through calcining the mixture of urea and thiourea in the presence of Pluronic F127, followed by deposition of bimetallic PtNi nanoparticles (NPs) via chemical reduction. It is found that the photocatalytic activity of PtNi/g-C3N4 nanotubes is strongly dependent on the molar ratio of Pt/Ni and the highest activity is observed for Pt1Ni1/g-C3N4. Under visible light (l > 420 nm) irradiation, the H2 generation rate over Pt1Ni1/g-C3N4 nanotubes is 104.7 mmol h?1 from a triethanolamine (10 vol%) aqueous solution, which is higher than that of Pt/g-C3N4 nanotubes (98.6 mmol h?1) and is about 47.6 times higher than that of pure g-C3N4 nanotubes. The cyclic photocatalytic reaction indicates that our Pt1Ni1/g-C3N4 nanotubes function as a stable photocatalyst for visible light-driven H2 production. The effect of bimetallic PtNi NPs in the transfer and separation of photogenerated charge carriers occurring in the excited g-C3N4 nanotubes was investigated by performing photoelectrochemical and photoluminescence measurements. Our results reveal that bimetallic PtNi could replace Pt as a promising cocatalyst for photocatalytic H2 evolution with better performance and lower cost.
关键词： Hydrogen evolution,g-C3N4,Nanotube,Bimetallic PtNi,Photocatalyst
更新于2025-09-23 15:21:21
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Simultaneously engineering K-doping and exfoliation into graphitic carbon nitride (g-C3N4) for enhanced photocatalytic hydrogen production
摘要： Doping and exfoliation are effective strategies to improve the photocatalytic activity of bulk graphitic carbon nitride (g-C3N4). Therefore, it can be inferred that engineering element-doping and exfoliation into g-C3N4 would further enhance the photocatalytic performance. Herein, we demonstrated a KOH-assisted hydrothermal-reformed melamine strategy for achieving the simultaneous K-doping and exfoliation of g-C3N4. The as-synthesized K-doped g-C3N4 ultrathin nanosheets displayed much enhanced photocatalytic hydrogen evolution rate (HER) of about 13.1 times higher than that of the bulk g-C3N4 under visible-light irradiation, achieving an apparent quantum efficiency of 6.98% at 420 nm. The improved photocatalytic HER can be attributed to the high surface area offering numerous photocatalytic active sites, enlarged conductive band edge optimizing photoreduction potential, and K-doping promoting charge generation and separation as well as the long life-time of photogenerated carriers. This work would provide a promising way to integrate co-doping and exfoliation into new g-C3N4-based materials.
关键词： Graphitic carbon nitride,Exfoliation,Photocatalytic hydrogen evolution,Nanosheet,K-doping
更新于2025-09-23 15:21:21
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The Reaction Mechanism for the Hydrogen Evolution Reaction on the Basal Plane Sulfur Vacancy Site of MoS2 Using Grand Canonical Potential Kinetics
摘要： We develop the grand canonical potential kinetics (GCP-K) formulation based on thermodynamics from quantum mechanics calculations to provide a fundamental basis for understanding heterogeneous electrochemical reactions. Our GCP-K formulation arises naturally from minimizing the free energy using a Legendre transform relating the net charge of the system and the applied voltage. Performing this macroscopic transformation explicitly allows us to make the connection of GCP-K to the traditional Butler-Volmer kinetics. Using this GCP-K based free energy, we show how to predict both the potential and pH dependent chemistry for a specific example, the hydrogen evolution reaction (HER) at a sulfur vacancy on the basal plane of MoS2. We find that the rate determining steps in both acidic and basic conditions are the Volmer reaction in which the second hydrogen atom is adsorbed from the solution. Using the our GCP-K formulation, we show that the stretched bond distances change continuously as a function of the applied potential. This shows that the main reason for the higher activity in basic conditions is that the transition state is closer to the product, which leads to a more favorable Tafel slope of 60mV/dec. In contrast if the transition state were closer to the reactant, where the transfer coefficient is less than 0.5 we would obtain a Tafel slope of almost 150mV/dec. Based on this detailed understanding of the reaction mechanism, we conclude that the second hydrogen at the chalcogenide vacant site is the most active towards the hydrogen evolution reaction. Using this as a descriptor, we compare to the other 2H group VI metal dichalcogenides and predict that vacancies on MoTe2 will have the best performance towards HER.
关键词： Grand Canonical Potential,Hydrogen Evolution Reaction,Molybdenum Disulfide,Electrochemistry
更新于2025-09-23 15:21:21
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Modified Nanopillar Arrays for Highly Stable and Efficient Photoelectrochemical Water Splitting
摘要： Atomically modified graphitic carbon nitride quantum dots (QDs), characterized by strongly increased reactivity and stability, are developed. These are deposited on arrays of TiO2 nanopillars used as a photoanode for the photoelectrochemical water splitting. This photoanode shows excellent stability, with 111 h of continuous work without any performance loss, which outperforms the best-reported results by a factor of 10. Remarkably, our photoanode produces hydrogen even at zero bias. The excellent performance is attributed to the enhancement of photoabsorption, as well as to the promotion of charge separation between TiO2 nanopillars and the QDs.
关键词： hydrogen evolution,quantum dots,graphitic carbon nitride,photoelectrochemistry,TiO2 nanopillars
更新于2025-09-23 15:21:21
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Ternary PtNiCu self-assembled nanocubes for plasmon-enhanced electrocatalytic hydrogen evolution and methanol oxidation reaction in visible light
摘要： The strong interaction among metal components results in the change of the electronic structure (e.g. d-band energy level) of noble metal-based alloy structures which enables the increase of catalytic activity. In this paper, self-assembled ternary PtNiCu and binary PtCu alloy nanocubes are synthesized by a one-pot high-temperature chemical reduction method. The growth mechanism of the alloy is investigated. The alloy is applied to visible light-assisted electrocatalytic hydrogen production and methanol oxidation. The ternary PtNiCu alloy exhibits superior catalytic performance (a minimum over potential of 15 mV at a current density of 10 mA cm-2, a Tafel slope of 24.1 mV/dec, and more excellent mass specific activity under visible light irradiation about 3.3 A mgPt -1), because of its regular morphology, more surface active sites, and more intense interaction between metal elements. Especially the localized surface plasmon resonance effect of Cu largely increases the electron density (photoelectric effect) on Pt under illumination, thereby further improves the photo-assisted hydrogen production and methanol catalytic oxidation performance. The results will promote efficient and accurate electrocatalysis process, paving new way for a brighter further in rational design of ternary plasmonic electrocatalysts and photoelectrocatalysis field.
关键词： Methanol oxidation reaction,Photoelectrocatalysis,Hydrogen evolution reaction,Ternary PtNiCu alloy
更新于2025-09-23 15:21:01
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Self-assembled CdS@BN core-shell photocatalysts for efficient visible-light-driven photocatalytic hydrogen evolution
摘要： CdS@BN NRs core-shell photocatalysts for hydrogen evolution were synthesized by a solvothermal and chemical adsorption method. CdS NRs coated by 5 wt% boron nitride (BN) shell exhibited remarkably visible-light photocatalytic hydrogen evolution activity of up to 30.68 mmol g?1 h?1, nearly 6.79 times higher than that of pure CdS NRs, and the apparent quantum efficiency at 420 nm was 7.5%. Transmission electron microscopy showed the CdS NRs were coated with a thin (~5 nm) BN layer, which together with the hydrogen evolution results proved the photocatalytic ability of CdS NRs was significantly improved. The hydrogen evolution rate of CdS NRs coated by 5 wt% BN remained at 91.4% after four cycles, indicating the photocorrosion of CdS NRs was effectively alleviated. Moreover, the large and close coaxial interfacial contact between the CdS core and the BN shell was beneficial to the separation and transfer of photogenerated electron-hole pairs.
关键词： Core-shell structure,Photocatalytic hydrogen evolution,CdS Nanorods,Boron nitride
更新于2025-09-23 15:21:01
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Determining Plasmonic Hot Electron and Photothermal Effects during H <sub/>2</sub> Evolution with TiN-Pt Nanohybrids
摘要： Hydrogen storage in chemical compounds is a promising strategy to enable lightweight, high density, and safe hydrogen technologies. However, the hydrogen release rate from these chemicals is limited by the intrinsic catalytic activity of metal catalysts, which can be enhanced by using light irradiation. Here nanohybrids including a core of plasmonic TiN and multiple Pt nanocrystal catalytic centers are assembled and show, under resonant conditions at 700 nm, hot electrons driven hydrogen evolution from ammonia borane at an apparent quantum yield of 120%. It is also demonstrated that solar irradiation enhances the activity of TiN-Pt nanohybrids by one order of magnitude through two synergistic mechanisms: the hot electrons and collective-heating contributions. Using the microscopic calculation of the photoinduced temperature around a single nanocrystal, it is revealed that the collective plasmonic heating regime dominates the macroscopic temperature distribution in the system. The presented data show that plasmonic hot electrons and photothermal heating can be used in synergy to trigger hydrogen release from ammonia borane on demand, providing a general strategy for greatly enhancing the activity in the dark of metal catalysts.
关键词： ammonia-borane,plasmonics,photocatalysis,titanium nitride,hydrogen evolution
更新于2025-09-23 15:21:01
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Metallic 1T-MoS2 nanosheets and their composite materials: Preparation, properties and emerging applications
摘要： Metallic 1T phase MoS2 nanosheets and their composite materials, with unique structure and unusual properties, have attracted increasing research interest in energy conversion/storage and catalysis in the past few years. In this work, an overview of the recent progress of metallic 1T-MoS2 nanosheets and their composite materials is presented. First, we focused on the controlled synthesis of 1T-MoS2 nanosheets and their composite materials using top-down and bottom-up approaches and their unusual properties while tuning the phase structure. Then, we discussed their promising applications in energy-related areas including hydrogen evolution reaction, supercapacitors, batteries, and photocatalysis. In addition, an in-depth understanding was provided on phase tuning of these advanced materials for improved performance. Finally, the existing challenges and future research in these emerging research areas are also described.
关键词： Batteries,Hydrogen evolution reaction,Metallic 1T-MoS2 nanosheets,Properties,Photocatalysis,Supercapacitors
更新于2025-09-23 15:21:01