Enhancing the hydrogen evolution activity of MoS basal planes and edges using tunable carbon-based supports

• Published in: Nanoscale 2021-02, Vol.13 (5), p.316-3118
• Main Authors: Ruffman, Charlie, Gordon, Calum K, Gilmour, J. T. A, Mackenzie, Frank D, Garden, Anna L
• Format: Article
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d0nr07100e

The hydrogen adsorption free energy (Δ G Hads ) on the basal plane and edges of MoS 2 is studied using periodic density functional theory, with the catalyst supported by a range of two-dimensional carbon-based materials. Understanding how Δ G Hads can be tuned with support gives insight into MoS 2 as a catalyst for the hydrogen evolution reaction. The supports studied here include graphene oxide materials, heteroatom doped (S, B, and N) graphene, and some insulator materials (hexagonal boron nitride and graphitic carbon nitride). For the basal plane of MoS 2 , a wide range of values for Δ G Hads are observed (between 1.4 and 2.2 eV) depending on the support material used. It is found that Δ G Hads relates directly to the energy of occupied p-orbital states in the MoS 2 catalyst, which is modified by the support material. On the Mo-edge of MoS 2 , different supports induce smaller variations in Δ G Hads , with values ranging between −0.27 and 0.09 eV. However, a graphene support doped with graphitic N atoms produces a Δ G Hads value of exactly 0 eV, which is thermodynamically ideal for hydrogen evolution. Furthermore, Δ G Hads is found to relate closely and linearly to the amount of charge transfer between MoS 2 and support when they adhere together. The support-induced tuning of Δ G Hads on MoS 2 observed here provides a useful tool for improving current MoS 2 catalysts, and the discovery of variables which mediate changes in Δ G Hads contributes to the rational design of new hydrogen evolution catalysts. Δ G H ads on the basal plane and edges of MoS 2 can be tuned using carbon based supports. The Δ G H ads value on the edge relates directly to the degree of charge transfer between MoS 2 and support.