Fe-doped and sulfur-enriched Ni3S2 nanowires with enhanced reaction kinetics for boosting water oxidation

Abstract

Exploring cost-effective and highly-active oxygen evolution reaction (OER) electrocatalysts is a pressing task to propel water electrolysis for green hydrogen production. Herein, we constructed a class of Fe-doped and S-enriched Ni3S2 nanowires electrocatalysts for optimizing the target intermediates adsorption to decrease the OER overpotentials at various current densities. The optimal Ni3S2-1.4%Fe electrocatalyst possesses the most active sites and exhibits an ultralow overpotential of 190 mV at 10 mA cm−2 with an excellent stability of > 60 h, exceeding the majority of recently-reported Ni3S2-based electrocatalysts. The trivalence Fe-doping not only reduces the electron density of the Ni center, but also enables the sulfur enrichment on the Ni3S2 surface, which greatly improves the intrinsic activity and the number of target intermediates (∗OOH). A novel methanol-assisted electrochemical evaluation further reveals that the Ni3S2-1.4%Fe electrocatalyst demonstrates a weaker binding ability to ∗OH with the rapid generation of ∗OOH species, and thus gives a lower apparent activation energy compared with the surface sulfur reduced ones. This work provides a new perspective for regulating the adsorption of intermediates through doping strategy.

Keywords

• Ni3S2
• Electrocatalyst
• Water splitting
• Oxygen evolution reaction