Single-atomic cobalt sites embedded in hierarchically ordered porous nitrogen-doped carbon as a superior bifunctional electrocatalyst

Significance A crucial component in the design of the single-atomic-site (SAS) catalysts for electrochemical applications is the specific surface area and porous structure. Here, we synthesize a type of Co catalyst with single-atomic Co sites embedded in hierarchically ordered porous N -doped carbon showing superior bifunctional activity for oxygen reduction reaction and hydrogen evolution reactions. Combined control experiments, density functional theory calculations, and in situ X-ray absorption spectroscopy measurements uncover that the atomically isolated Co-N 4 coordination and the unique 3D porous open architecture synergistically contribute to the excellent catalytic performance. The dual-template-assisted strategy sheds insight on the construction of structurally controllable SAS catalysts for various applications, and the investigation of enhancement mechanism provides great help to boost the efficiency of future cost-effective electrocatalysts.