Graphene quantum dot enabled interlayer spacing and electronic structure regulation of single-atom doped MoS₂ for efficient alkaline hydrogen evolution

Interlayer engineering of two-dimensional (2D) materials is believed to be a key to enhance their performance for catalysis and other applications. Herein, molybdenum disulfide intercalated with heteroatom-doped graphene quantum dots and individually dispersed Co atoms (GQD/Co-MoS₂) is readily synthesized by a one-pot hydrothermal reaction. With better long-term stability, GQD/Co-MoS₂ shows comparable catalytic performance as commercial Pt/C catalyst for hydrogen evolution reaction in alkaline medium at low current densities (overpotential of 53 vs 44 mV at 10 mA cm⁻²) and outperforms Pt/C at high current densities (106 vs 172 mV at 100 mA cm⁻²). Based on both experimental and theoretical investigations, the outstanding performance is mainly attributed to the enlarged interlayer spacing and electronic coupling at the 0D/2D van der Waals heterojunctions between GQDs and Co-doped MoS₂. In principle, a variety of GQD intercalated 2D materials with atomic doping of one or more metallic elements can be similarly synthesized for diverse applications.