Partially Oxidized Cu@Graphene Clusters for Hydrogen Evolution Reaction

A facile one‐step chemical vapor deposition (CVD) synthesis of multilayer graphene‐wrapped copper nanoparticles (MLG‐CuNPs), followed by an air‐heating step to yield hollow clusters consisiting of partially oxidized‐MLG‐CuNPs, is investigated for the application on hydrogen evolution electrocatalysis. Scanning electron microscopy (SEM) and high‐resolution transmission electron microscopy (HRTEM) confirm the hollow architectures of the clusters, while X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS) analyses verify the surface oxidation of MLG‐CuNPs and the retention of conductive copper core. The oxidized‐MLG‐CuNPs electrode can drive the hydrogen evolution reaction (HER) at a current density of 10 mA cm ⁻² with a small overpotential of 290 mV and the Tafel slope of 151 mV dec. ⁻¹ ; while the overpotential values of oxidized‐MLG and oxidized‐CuNPs electrode for reaching the same current density are 569 mV and 417 mV, respectively. Moreover, the oxidized‐MLG‐CuNPs electrode remains stable in an alkaline electrolyte for 500 cycles. These results highlight the potential of oxidized‐MLG‐CuNPs as an efficient and durable nonprecious electrocatalyst for hydrogen evolution in alkaline electrolyte.