Porous N, P co-doped carbon-coated ultrafine Co2P nanoparticles derived from DNA: An electrocatalyst for highly efficient hydrogen evolution reaction

•A novel, one-step and non-toxic strategy is used to synthesize Co2P@NPC.•DNA serves as N, P co-doped carbon substrate and phosphorous source for forming TMPs.•The Co2P nanoparticles are uniformly dispersed with the diameter of 3.5 nm.•The Co2P@NPC exhibit efficient HER activity due to the synergistic effect. A novel freeze-drying accompanied by direct pyrolysis method was conducted to fabricate porous N, P co-doped carbon-coated ultrafine Co2P nanoparticles (Co2P@NPC) using deoxyribonucleic acid (DNA). DNA, for the first time, is used as a precursor of the N, P co-doped carbon substrate, as well as an in-situ P source for the preparation of Co2P. Benefiting from the ultrafine Co2P nanoparticles and the porous N, P co-doped carbon, the Co2P@NPC shows excellent performance toward hydrogen evolution reaction (HER). Moreover, the N, P co-doped carbon shell can successfully prevent the Co2P nanoparticles from corrosion or decomposition, and it ensures the good interface stability. These results may provide a novel strategy for the design and synthesis of N, P co-doped carbon encapsulated ultrafine metal phosphides electrocatalysts.