Metal/antiperovskite metal nitride composites Ag/AgNNi3 as novel efficient electrocatalysts for hydrogen evolution reaction in alkaline media

Searching for effective hydrogen evolution reaction (HER) electrocatalysts is crucial for water splitting. Transition metal nitrides (TMNs) are very attractive potential candidates since of high electrical conductivity, robust stability, element rich and high activity. Antiperovskite metal nitrides provide chemical flexibility since two different types of transition metal elements are contained, allowing partial substitution both for A- and M-sites. Herein, we report a novel antiperovskite metal nitride AgxNi1-xNNi3 (0 ≤ x ≤ 0.80) thin film used as highly effective HER electrocatalysts. Pure phase antiperovskite nitride can be successfully obtained for AgxNi1-xNNi3 with x less than 0.80. The Ag0.76Ni0.24NNi3 towards HER shows an overpotential of 122 mV at 10 mA cm−2 in alkaline media. Furthermore, considering the role of Ag for adsorbing hydroxyl groups, chemical engineering has been carried out for designing metal/antiperovskite nitride Ag/AgxNi1-xNNi3 composite electrocatalysts. The 0.18 Ag/Ag0.80Ni0.20NNi3 electrocatalyst shows a mere 13 and 81 mV of overpotential to reach 1 and 10 mA cm−2, respectively, showing high durability in alkaline media. These results will provide a novel type of HER catalysts based on antiperovskite metal nitrides and a strategic design for metal/antiperovskite metal nitride composite electrocatalysts for HER in alkaline media.