Engineering nickel phosphides for electrocatalytic hydrogen evolution: A doping perspective

•Progress in NixPy doping for electrocatalytic HER is outlined.•Intrinsic and extrinsic doping strategies for NixPy are systematically reviewed.•Various effects of doping on HER activity descriptors are delineated.•Current arsenal of doped-NixPy materials for HER are critically appraised.•Future directions and recommendations of NixPy are presented.