Fine Rhodium Phosphides Nanoparticles Embedded in N, P Dual-doped Carbon Film: New Efficient Electrocatalysts for Ambient Nitrogen Fixation

•A series of RhP*x@NPC catalysts were developed by the combination of tunable morphology and controllable structure.•The ratios of Rh to P may be gradually tuned to achieve the optimum product that exhibits best catalytic activity.•DFT calculations suggest that the electrocatalytic activities can be greatly meliorated by introducing of P into Rh lattice.•The new Rh2P@NPC exhibits excellent NRR activity.