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Colloidally synthesized defect-rich $$\hbox {MoSe}_{2}$$ MoSe 2 nanosheets for superior catalytic activity
摘要： Transition metal dichalcogenide (TMD) nanosheets (NSs) with defect-rich and vertically aligned edges are highly advantageous for various catalytic applications. However, colloidal synthesis of defect-rich NSs with thickness variation has been a challenging task. Here, we report a colloidal synthesis of 2H-MoSe2 NSs having a large number of defects and vertically aligned edges, where the thickness is varied by changing the amount of coordinating solvent. The Se-vacancies in these NSs have introduced defect sites which are corroborated by the presence of additional vibration modes in Raman spectra. These NSs exhibit electrocatalytic hydrogen evolution reaction performances with a low overpotential (210–225 mV) at 10 mA cm?2 current density and a small Tafel slope (54–68 mV per decade). Moreover, these MoSe2 NSs are also employed as counter electrodes (CEs) for the fabrication of dye sensitized solar cells via a cost-effective and simplified procedure. The power conversion efficiencies of 7.02 ± 0.18%, comparable with Pt CE (7.84 ± 0.10%) could be routinely achieved. These results demonstrate a novel synthetic strategy to prepare layered TMDs with superior catalytic applications.
关键词： counter electrode,Transition metal dichalcogenides,dye sensitized solar cells,MoSe2 nanosheets,hydrogen evolution reaction
更新于2025-11-19 16:56:35
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Thiourea-assisted coating of dispersed copper electrocatalysts on Si photocathodes for solar hydrogen production
摘要： Photoelectrochemical water splitting can convert solar energy into clean hydrogen energy for storage. It is desirable to explore non-precious electrocatalysts for practical applications of a photoelectrode in a large scale. Here, we developed a facile spin-coating and in-situ photoelectrochemical reduction method to prepare a dispersed Cu electrocatalyst on a Si photocathode, which improves the performance remarkably. We find that thiourea in the precursor solution for spin-coating plays an important role in obtaining dispersed Cu particles on the surface of a Si photoelectrode. With thiourea in the precursor, the Cu/Si photocathode shows higher performance than the one without thiourea. Moreover, the Cu/Si photocathode also indicates good stability after 16 h illumination.
关键词： In-situ photoelectrochemical reduction,Cu electrocatalyst,Thiourea,Hydrogen evolution reaction
更新于2025-11-19 16:51:07
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Synthesis of a MoS <i> <sub/>x</sub></i> -O-PtO <i> <sub/>x</sub></i> Electrocatalyst with High Hydrogen Evolution Activity Using a Sacrificial Counter-Electrode
摘要： Water splitting is considered to be a very promising alternative to greenly produce hydrogen, and the key to optimizing this process is the development of suitable electrocatalysts. Here, a sacrificial-counter-electrode method to synthesize a MoSx/carbon nanotubes/Pt catalyst (0.55 wt% Pt loading) is developed, which exhibits a low overpotential of 25 mV at a current density of 10 mA cm?2, a low Tafel slope of 27 mV dec?1, and excellent stability under acidic conditions. The theory calculations and experimental results confirm the high hydrogen evolution activity that is likely due to the fact that the S atoms in MoSx can be substituted with O atoms during a potential cycling process when using Pt as a counter-electrode, where the O atoms act as bridges between the catalytic PtOx particles and the MoSx support to generate a MoSx–O–PtOx structure, allowing the Pt atoms to donate more electrons thus facilitating the hydrogen evolution reaction process.
关键词： sacrificial-counter-electrodes,O substitution,MoSx,hydrogen evolution reaction,PtOx
更新于2025-09-23 15:23:52
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Fabrication of new metal-free materials for the hydrogen evolution reaction on base of the acridine derivatives immobilized on carbon materials
摘要： The process of adsorption on carbon material (Vulcan XC-72 (VU)) of organic heterocyclic compounds: acridine (I) and its derivatives 9-phenylacridine (II) and N-methyl-9-phenylacridium iodide (III) was studied in detail. Quantitative data on physical adsorption were obtained for all compounds. Based on the adsorption isotherms of Langmuir, the adsorption equilibrium constants K, the parameter A∞ and ΔG0 ad were calculated. It has been shown that the adsorption of compounds I and II is a structurally dependent process that depends on the nature and size of the functional substituents in the molecule, and the adsorption of compound III has a complex mechanism and partially proceeds through the stabilization stage by the functional groups present on the surface (-COOH, -COH, -OH). With the use of quantum chemical calculations, it has been established that the process of adsorption of compounds on the surface of a carbon materials having sections with a graphite-like structure is thermodynamically unprofitable because of the high difference in the energies of the adsorbent's boundary orbitals and the substrate. Using the cyclic voltammetry method, the electrochemical properties of organic compounds immobilized on the surface of a carbon material were studied.
关键词： Electocatalysis,Acridine derivatives,Immobilization,Adsorption,Carbon materials,Hydrogen evolution reaction
更新于2025-09-23 15:22:29
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Electronic structure and hydrogen evolution reaction in layered ReS<sub>2</sub> regulated by alkali-metal atom intercalation
摘要： Recently, the atom intercalation method has been developed and applied into two-dimensional (2D) materials to regulate their pristine physical property. However, as an important application in hydrogen evolution reaction (HER), the influence of alkali-metal-intercalated technology upon 2D material's electronic structure and catalytic activity should be investigated systematically. In this work, layered ReS2 crystals with a charge decoupling are chosen as a model to explore changes in electronic structure and Gibbs free energies induced by alkali-metal intercalated compounds and external strain. The calculated results disclose that the structural transformation induced by intercalated alkali atom and external strain not only leads to decrease in band gap of ReS2 but also make Gibbs free energy of adsorbed hydrogen close to zero. Our calculations provide an insight to improve HER performance by a simple alkali-metal-intercalated technology.
关键词： hydrogen evolution reaction,electronic structure,alkali-metal-intercalated technology
更新于2025-09-23 15:22:29
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Enhanced light harvesting and electron-hole separation for efficient photocatalytic hydrogen evolution over Cu7S4-enwrapped Cu2O nanocubes
摘要： P-type Cu2O is an advantageous photocatalyst as the appropriate bandgap structure and low-cost. However, poor photocatalytic and instability of such promising material is still a great challenge. Here the core-shell Cu7S4-coated Cu2O nanocubes (Cu2O/Cu7S4 NCs) were successfully synthesized by solution method coupled with anion exchange, integrated structure of Cu2O/Cu7S4 NCs exhibited apparent improved photocatalytic hydrogen evolution activity compared with Cu2O photocatalyst. Particularly, Cu2O/Cu7S4 NCs had a high hydrogen production rate of 1689.00 μmol·g-1·h-1 under full spectra irradiation with additives of Na2SO3, which was higher than that of Cu2O NCs with a factor of 1.71 times. Excellent synergistic effect of Cu2O and Cu7S4 can be responsible for the improved hydrogen evolution properties, namely, the presence of Cu7S4 with localized surface plasma resonance (LSPR) can promote the photogenerated electrons transfer from the Cu2O surface, prolong the photogenerated holes lifetime, accelerate the separation of photogenerated electrons and holes, and ameliorate the photoelectric properties of semiconductors. The in situ formed multifunctional Cu7S4 layer offers a promising avenue to design photocathodes rationally for photocatalytic water reduction.
关键词： Photocatalyst,Localized surface plasma resonance,Electron-hole separation,Hydrogen evolution reaction,Cu2O/Cu7S4 nanocubes
更新于2025-09-23 15:22:29
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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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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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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
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Electrochemical Exfoliation of MoS <sub/>2</sub> Crystal for Hydrogen Electrogeneration
摘要： Transition metal dichalcogenides (TMDs) have recently emerged within the group of 2D materials due to their electrical, catalytic and optical properties significantly enhanced and useful when down-sized to single layer. In particular, MoS2 has attracted much attention due to its semiconducting nature with a useful band gap when present as single layer, the enhanced photoluminescence, but also importantly the excellent catalytic properties towards the electrochemical hydrogen evolution. We present here the preparation of thin layers MoS2 nanosheets with enhanced catalytic properties towards the hydrogen evolution reaction by means of an easy and fast electrochemical top-down exfoliation procedure in aqueous solution from a naturally occurring MoS2 crystal. After structural and chemical characterization with STEM, AFM, XPS and Raman spectroscopy electrochemical investigations were performed to test catalytic properties in acidic solution for the electrogeneration of hydrogen and compare it to MoS2 nanosheets obtained through the widely employed chemical Li intercalation/exfoliation. Electrochemically exfoliated MoS2 shows lower Tafel slope than its counterpart obtained with chemical exfoliation.
关键词： hydrogen evolution reaction,molybdenum sulfide,electrochemistry,layered compound,exfoliation
更新于2025-09-23 15:21:01