Mo2C-embedded biomass-derived honeycomb-like nitrogen-doped carbon nanosheet/graphene aerogel films for highly efficient electrocatalytic hydrogen evolution

Abstract

Honeycomb-like Mo₂C@nitrogen-doped carbon nanosheet/graphene (Mo₂C@N-DC/G) aerogel films were synthesized successfully by dissolution and coagulation of chitin and graphene oxide, and subsequent simultaneous carbonization of chitin and carbothermal reduction of hexaammonium molybdate. The resulting Mo₂C@N-DC/G aerogel films exhibited homogeneous interconnected open-cell architectures, and the Mo₂C nanoparticles were homogeneously embedded within a chitin/graphene oxide aerogel derived 3D highly conductive N-DC/G nanonetwork. Benefitting from the unique three-dimensional honeycomb-like architecture and characteristics with excellent electron transportation, abundant active sites, strong interaction between Mo₂C nanocrystals and N-DC/G frameworks, the as-prepared catalyst exhibited remarkable catalytic activity and endurance for hydrogen evolution reaction (HER). The optimized Mo₂C@N-DC/G electrocatalyst exhibits excellent HER electrocatalytic activity with a low overpotential of 107 mV to achieve a cathodic current density of 10 mA cm⁻² and a small Tafel slope of 65.8 mV dec⁻¹ in 0.5 M H₂SO₄ solution. Moreover, it also displays outstanding long-term electrochemical stability, exhibiting no significant decay after 1500 cycles and 15 h of continuous testing at fixed overpotentials. This work will illuminate an entirely new avenue for exploring various low-cost, high-performance self-supported electrode materials for various electrochemical energy conversion and storage applications.