Defect engineering in graphene-based nanospheres enhanced hydrogen evolution reaction performance of ruthenium nanoparticles

Abstract The lattice defects in graphene-based carbon materials have been proven to play a critical role for improving the hydrogen evolution reaction (HER) behavior of supported metal catalysts. Nevertheless, accurately manipulating the intensity and distribution of defects for the optimal carbon structure still remains a significant challenge. Here, the microstructures of graphene nanospheres (GNs), in the form of defects distribution and graphitization degree, are accurately regulated by annealing. The optimal electrocatalyst (Ru@GNs300) was achieved by annealing at 300 °C, giving an overpotential of 40 mV at a current density of 10 mA cm−2 together with superior durability in the HER performance test in 1 M KOH. Particularly, the Ru@GNs catalyst has been annealed in situ in transmission electron microscope to monitor its structural evolution. The results indicate that the aggregation of Ru nanoparticles have not been observed up to 900 °C, while the graphitization degree of carbon support increased with elevated temperature. It is worth noting that the optimized electrocatalytic activity of Ru@GNs300 originates from the annealing induced defects regulating of GNs. Thus, the structural optimizing of carbon supports by defect engineering provides an efficient approach to improve the catalytic performance for HER.