Improved High-Current-Density Hydrogen Evolution Reaction Kinetics on Single-Atom Co Embedded in Order Pore Structured Nitrogen Assembly Carbon Support

Single-atom catalysis is a subcategory of heterogeneous catalysis with well-defined active sites. Numerous endeavors have been devoted to developing single-atom catalysts for industrially applicable catalysis, including hydrogen evolution reaction (HER). High current density electrolyzers have been pursued for single-atom catalysts to increase active site density and enhance mass transfer. Here, we reason that single-atom metal embedded in nitrogen assembly carbon (NAC) catalysts with high single-atom density, large surface area, and ordered mesoporosity, could fulfill the industrially applicable HER. Among several different single-atom catalysts, the HER overpotential with the best performing Co-NAC reaches 200 mA cm⁻² current density at 310 mV, relevant to industrial applicable current density. Density functional theory (DFT) calculations suggest the feasible hydrogen binding on single-atom Co results in the promising HER activity over Co-NAC. The best-performing Co-NAC shows robust performance under alkaline conditions at 50 mA cm⁻² current density for 20 h in an H-cell and at 150 mA cm⁻² current density for 100 h in a flow cell.