In-situ exfoliating graphene to anchor Mo2C NPs and modulate crystal planes for hydrogen production

Abstract

An economical and efficient noble metal-free catalyst is necessary for large-scale hydrogen production. Here, Mo₂C nanoparticles (NPs) were well-dispersed on the surface of 2D graphene nanosheets by in-situ propping oxide graphene (GO) layers, anchoring molybdate ions between GO layers and pyrolysis. The exposed crystal planes were also adjusted by above strategy. The results indicate that uniform and well-dispersed Mo₂C NPs with a narrow size distribution were anchored on 2D rGO nanosheets and exposed dual crystal planes. The results of hydrogen evolution reaction (HER) show that the optimal Mo₂C/rGO catalyst only needs low overpotential (η₁₀, 112 mV) to drive 10 mA cm⁻² in alkaline solution, and η₁₀ only increased by 12 mV after 1000 cycles test, indicating high activity and stability for HER. Notably, the overpotential is below than that of Pt/C commercial catalyst when current density is more than 100 mA cm⁻¹. The excellent performance is benefit from low hydrogen adsorption Gibbs free energy (ΔG_H∗) on the Mo₂C catalyst. Therefore, the proposed strategy is efficient to prepare well-dispersed and dual crystal planes-exposed Mo₂C NPs for electrocatalytic hydrogen evolution.