Heazlewoodite, Ni[subscript 3]S[subscript 2]: A Potent Catalyst for Oxygen Reduction to Water under Benign Conditions

Abstract

Electrodeposited thin films and nanoparticles of Ni[subscript 3]S[subscript 2] are highly active, poison- and corrosion-resistant catalysts for oxygen reduction to water at neutral pH. In pH 7 phosphate buffer, Ni[subscript 3]S[subscript 2] displays catalytic onset at 0.8 V versus the reversible hydrogen electrode, a Tafel slope of 109 mV decade[superscript –1], and high faradaic efficiency for four-electron reduction of O[subscript 2] to water. Under these conditions, the activity and stability of Ni[subscript 3]S[subscript 2] 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.