Heazlewoodite, Ni₃S₂: A Potent Catalyst for Oxygen Reduction to Water under Benign Conditions

Abstract

Electrodeposited thin films and nanoparticles of Ni₃S₂ are highly active, poison- and corrosion-resistant catalysts for oxygen reduction to water at neutral pH. In pH 7 phosphate buffer, Ni₃S₂ displays catalytic onset at 0.8 V versus the reversible hydrogen electrode, a Tafel slope of 109 mV decade^–1, and high faradaic efficiency for four-electron reduction of O₂ to water. Under these conditions, the activity and stability of Ni₃S₂ exceeds that of polycrystalline platinum and manganese, nickel, and cobalt oxides, illustrating the catalytic potential of pairing labile first-row transition metal active sites with a more covalent sulfide host lattice