Construction of N-doped carbon frames anchored with Co single atoms and Co nanoparticles as robust electrocatalyst for hydrogen evolution in the entire pH range

The development of low-cost, efficient, and high atomic economy electrocatalysts for hydrogen evolution reaction (HER) in the entire pH range for sustainable hydrogen production is of great importance but still challenging. Herein, we synthesize a highly dispersed N-doped carbon frames (NCFs) anchored with Co single atoms (SAs) and Co nanoparticles (NPs) catalyst by a doping-adsorption-pyrolysis strategy for electrocatalytic hydrogen evolution. The Co SAs-Co NPs/NCFs catalyst exhibits an excellent HER activity with small overpotential, low Tafel slope, high turnover frequency as well as remarkable stability. It also exhibits a superior HER performance in the entire pH range. Combining with experimental and theoretical calculation, we find that Co SAs with Co-N3 coordination structure and Co NPs have a strong interaction for promoting synergistic HER electrocatalytic process. The H2O molecule is easily activated and dissociated on Co NPs, while the generated H* is easily adsorbed on Co SAs for HER, which makes the Co SAs-Co NPs/NCFs catalyst exhibit more suitable H adsorption strength and more conducive to the activation and dissociation of H2O molecules. This work not only proposes a novel idea for constructing coupling catalyst with atomic-level precision, but also provides strong reference for the development of high-efficiency HER electrocatalysts for practical application.