Catalytic Performances of NiCuP@rGO and NiCuN@rGO for Oxygen Reduction and Oxygen Evolution Reactions in Alkaline Electrolyte
© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim In this paper, the reduced graphene oxide (rGO) supported nickel-copper phosphide (NiCuP@rGO) nanotube and nickel-copper nitride (NiCuN@rGO) nano-rods were synthesized and the catalytic performances of them for oxygen reduction reaction (ORR) and oxygen evolution reactions (OER) in alkaline electrolyte were reported. Structure investigations show that the NiCuP@rGO has a nanotube structure, whereas NiCuN@rGO has aggregated nanorods structure. The catalytic performance of NiCuP@rGO and NiCuN@rGO for ORR and OER were investigated by cyclic voltammetry (CV), Tafel, rotating disc electrode (RDE) and rotating ring disc electrode (RRDE) tests and other methodologies. Results showed that both NiCuP@rGO and NiCuN@rGO had good catalytic performance for ORR, which major happened through 4-electron pathway. Thus, the catalytic performance of NiCuP@rGO for OER was much higher than that of NiCuN@rGO. The great difference in the catalytic performance should be attributed to the different electronegativity of nitrogen and phosphorus. The higher negativity of nitrogen facilitates the electron transfer from catalyst to oxygen molecules but inhibits the acceptance of electron from hydroxide ions in the alkaline electrolyte. On the other hand, the nanotube structure of NiCuP@rGO with superior electron conductivity facilitates the OER reaction on the catalyst surface. This paper provides a reference for the design of novel catalysts for ORR and OER.