Synthesis of Cobalt Phosphide Nanoparticles Supported on Pristine Graphene by Dynamically Self‐Assembled Graphene Quantum Dots for Hydrogen Evolution

A highly active, durable, and low‐cost hydrogen evolution reaction (HER) catalyst is desirable for energy storage through water splitting but its fabrication presents great challenges. Herein, mediated by dynamically self‐assembled graphene quantum dots (GQDs), small, uniform, high‐density, and well‐dispersed CoP nanoparticles were grown in situ on pristine graphene for the first time. This hybrid nanostructure was then employed as HER electrocatalyst, showing an onset potential of 7 mV, an overpotential of 91.3 mV to achieve 10 mA cm−2, a Tafel slope of 42.6 mV dec−1, and an exchange current density of 0.1225 mA cm−2, all of which compare favorably to those of most reported non‐noble‐metal catalysts. The developed catalyst also exhibits excellent durability with negligible current loss after 2000 cyclic voltammetry cycles (+0.01 to −0.17 V vs. RHE) or 34 h of chronoamperometric measurement at an overpotential of 91.3 mV. This work not only develops a new strategy for the fabrication of high‐performance and inexpensive electrocatalysts for HER but also provides scientific insight into the mechanism of the dynamically self‐assembled GQDsmediated synthesis process.