N,S co-doped porous carbon with Co9S8 prepared with a Co-FF-derived Co3O4 template: a bi-functional electrocatalyst for rechargeable zinc–air batteries
N,S-codoped porous carbon materials containing Co9S8 nanoparticles were prepared by one-step carbon-vulcanization using Co3O4@PDA and they exhibited excellent bi-functional electrocatalytic activity comparable to Pt/C + RuO2 in alkaline medium.