▎ 摘　　要

Reducing precious metal loading is of paramount importance in electrocatalysis. Here, we propose an efficient strategy to synthesize low-Pt electrocatalysts (3.9 wt%) with hydrogen evolution reaction (HER) performance comparable to that of a state-of-the-art 20% Pt/C electrocatalyst. Graphene quantum dots (GQDs) were used as building blocks for carbon support. Cobalt catalyzed the GQDs assembly into porous carbon nanosheets with plenty of defects and high N doping. Pt was deposited on the support via in-situ electrochemical cycling. The combination of low Pt nanoparticles loading and defective carbon remarkably enhanced the HER activity in both acid (overpotential = 84 mV at 100 mA cm(-2), Tafel slope of 45 mV dec(-1)) and alkaline electrolytes (overpotential = 300 mV at 100 mA(-2), Tafel slope of 152 mV dec(-1)) while showing excellent stability and durability for 45 h. (C) 2021 Elsevier B.V. All rights reserved.