Encapsulating Co2P@C Core-Shell Nanoparticles in a Porous Carbon Sandwich as Dual-Doped Electrocatalyst for Hydrogen Evolution

A new, highly-efficient and pH-universal sandwich-architecture HER electrocatalysts, constructed by 0-dimensional N and P dual-doped core-shell Co2P@C nanoparticles embedded into a 3-dimensional porous carbon sandwich (Co2P@N,P-C/CG), was synthesized by a facile two-step method of hydrothermal carbonization (HTC) and pyrolysis. Owing to the synergistic effect of N, P-codoped Co2P@C core-shell and sandwich-nanostructural substrates, it increases the interfacial electron transfer rate and the number of active sites. Because of the presence of high surface area and large porous sizes, it improves the mass transfer dynamics. This nanohybrid shows remarkable electrocatalytic activity toward the HER in wide pH value, with good stability. The computational study and experiments reveal that the carbon atoms closed to N and P heteroatoms dopants on the shell of Co2P@N,P-C are the effective active sites for HER catalyst, and Co2P and N, P dopants synergistically optimize the binding free energy of H* on the active sites.