Novel (Ni, Fe)S 2 /(Ni, Fe) 3 S 4 solid solution hybrid: an efficient electrocatalyst with robust oxygen-evolving performance

Fabrication of high-activity electrocatalysts with operational stability is desperately needed to achieve efficient energy conversion. Herein, for the first time, we highlight a novel electrocatalyst based on binary nickel iron sulfide solid solution hybrids on carbon cloth for oxygen evolution reaction. Benefitting from the synergistic effect of varied phases and the interfacial connection between (Ni, Fe)S2 and (Ni, Fe)3S4 to accelerate the charge transport, the Ni incorporation to optimize the electronic structure of the hybrids and the downshift of the d-band center to facilitate the desorption of oxygen intermediates, the partial charge-transfer between Fe and Ni to boost the generation of catalytically active Ni3+ as well as the unique nanosphere structure to offer enough buffer area for the volume changes during constant redox reactions, the obtained binary nickel iron sulfide hybrids ((Ni, Fe)S2/(Ni, Fe)3S4) display high catalytic reactivity with a low overpotential of 210 mV to reach the current density of 10 mA cm−2, and excellent stability with negligible activity deterioration, making the hybrid a promising candidate for electrocatalytic alkaline water oxidation.