Mesoporous Ni3S2@Ni incorporated and N-doped Carbon Nanohorns-Carbon Nanosheets: Heterostructure Construction and Electron Modulation for an Efficient Electrocatalyst in Oxygen Evolution Reaction

Abstract

Oxygen evolution reaction (OER) is a key electrochemical reaction in water splitting, but its slow kinetics necessitates the engagement of electrocatalysts to reduce the overpotential and improve reaction efficiency. In this work, a nanocomposite of mesoporous Ni3S2@Ni incorporated and N-doped carbon nanohorns pinned on carbon nanosheets (Ni3S2@Ni-CNH-CNS) was prepared by nickel-catalyzed graphitization of melamine/span 80 and the post partial vulcanization. The nanocomposite electrocatalyst with rich mesopores, abundant exposed active sites and modulated electronic structure facilitated the interfacial electron transference and bulk electron-ion transportation for OER. In 1.0 M KOH, a low overpotential of 210 mV is required for Ni3S2@Ni-CNH-CNS to achieve a geometric current density of 10 mA cm-2, which is lower to 338 mV of RuO2 supported on a commercial carbon nanotube. More importantly, Ni3S2@Ni-CNH-CNS shows robust durability for OER catalysis at 10 mA cm-2 within 24 h and maintains a 96% current density in OER. DFT calculation discloses that the electronic interaction between Ni3S2 and Ni-N-C can synergistically regulate the binding energy towards *O intermediate, lower the activation barrier, and consequently enhance the OER catalytic activity.