Charge-Transfer Induced High Efficient Hydrogen Evolution of MoS2/graphene Cocatalyst

Abstract

The MoS 2 and reduced graphite oxide (rGO) composite has attracted intensive attention due to its favorable performance as hydrogen evolution reaction (HER) catalyst, but still lacking is the theoretical understanding from a dynamic perspective regarding to the influence of electron transfer, as well as the connection between conductivity and the promoted HER performance. Based on the first-principles calculations, we here clearly reveal how an excess of negative charge density affects the variation of Gibbs free energy (ΔG) and the corresponding HER behavior. It is demonstrated that the electron plays a crucial role in the HER routine. To verify the theoretical analyses, the MoS 2 and reduced graphite oxide (rGO) composite with well defined 3-dimensional configuration was synthesized via a facile one-step approach for the first time. The experimental data show that the HER performance have a direct link to the conductivity. These findings pave the way for a further developing of 2-dimension based composites for HER applications.In recent years, the demands for the renewable and clean energy resources gradually become urgent for the growing problems of environmental pollution. Hydrogen, as a clean and efficient fuel source, has been vigorously pursued as a promising candidate for future energy carrier. The traditional way to produce hydrogen involving CO 2 release and the high temperature reaction condition will be phased out gradually for the related disadvantages 1 , therefore, developing techniques to produce hydrogen from economic and renewable resources can be beneficial to a significant reduction in consumption of fossil fuel and a lower CO 2 emissions. Recently, massive efforts have been devoted to producing hydrogen by electrochemical or photoelectrocatalytic processes from water splitting [2][3][4] . So far, many kinds of materials including nickel alloy, carbides, polymeric carbon nitride and transition metal chalcogenides have been attempted to serve as the HER catalysts [5][6][7] . Among these, the most common catalysts used for HER are noble metals, such as ruthenium, iridium and platinum 8,9 . In general electrochemical routines, nickel alloy catalysts present high activity for the HER in alkaline electrolytes, while they are often degraded in acidic solutions. Pt has very small over potential for HER and exhibits excellent electrocatalytic activity, but the scarcity and high prices of these kinds of noble metals prohibit their widespread applications 10

Narrow‐Gap Quantum Wires Arising from the Edges of Monolayer MoS2 Synthesized on Graphene

“…This will facilitate the electron transfer from electrode to Gr and then to MoS 2 , forming an excessive negative charge density. This will effectively prompt the Gibbs free energy of adsorbed H shifting to the thermoneutral state (≈0 eV) and encourage the overall HER performance …”

Dependence of the Properties of 2D Nanocomposites Generated by Covalent Crosslinking of Nanosheets on the Interlayer Separation: A Combined Experimental and Theoretical Study

“…The higher activity of MoS 2 ‐graphene composites is attributed to charge transfer from graphene to MoS 2 through the network. This is probably due to the built‐in electric field at the graphene‐MoS 2 interface which facilitates charge transfer across the interface . Our control experiments show that graphene alone is not active under similar conditions studied for HER (Figure S9a).…”

In-situ wet tearing based subnanometer MoSeS for efficient hydrogen evolution

“…What's more, the wavenumber of A 1g peak became smaller after the tearing. This red-shift of A 1g peak indicates the decrease of the MoS 2 layer numbers and the appearance of the final products CNTs@NiSe@MoSeS nanocomposites [52], corresponding to the aforementioned mapping, XRD and HRTEM results.…”