▎ 摘　　要

Electrocatalytic hydrogen production is considered to be one of the cleanest hydrogen production pathways, while the development of advanced electrocatalysts with high activity and low cost is currently the biggest challenge in this field. Here, we report a robust and cost-effective approach to the construction of the 0D/2D heterojunctions made from small-sized graphene quantum dots strongly coupled with ultrathin Ti3C2Tx MXene nanosheets (GQDs/Ti3C2Tx) via a controllable assembly process. The newly-designed heterostructure provides unique structural advantages including large specific surface area, uniform dispersion of quantum dots with abundant active edge sites, desirable electronic structures, and good electronic conductivity, which endow the resulting GQDs/Ti3C2Tx catalyst with excellent hydrogen evolution properties with a low onset potential, a small Tafel slope, and long service life, which are significantly better than the bare quantum dots and Ti3C2Tx catalysts.