Noble-metal-free, atomically thin CuInP2Nx nanosheets as highly efficient, stable, and low-cost electrocatalysts in acid oxygen evolution reactions

Abstract

Highly active and durable electrocatalysts for the oxygen evolution reaction (OER) in acidic conditions are highly desired for renewable energy nowadays. In this work, a new type of noble-metal-free, atomically thin CuInP₂N_x nanosheets was synthesized through the facile nitridation of the corresponding CuInP₂S₆ and utilized for electrocatalytic water splitting. The combined merits of metal nitrides and the 2D morphology improved the OER performance, achieving an overpotential of 356 mV at a current density of 10 mA cm⁻² and a long-term durability of 60 h in 0.5 M H₂SO₄ electrolyte. The changes in the electronic structure with the introduction of N in CuInP₂N_x efficiently lower the energy barriers of intermediates, especially those of OH* and OOH*, thus causing the OER process to be more thermodynamically favourable. This work may provide inspiration for the exploration of cost-effective, novel transition-metal nitride catalysts with excellent OER performance and stability.