Strong hydrophilicity NiS2/Fe7S8 heterojunctions encapsulated in N-doped carbon nanotubes for enhanced oxygen evolution reaction

Abstract

The construction of active sites with excellent water oxidation activity is of great significance in the design of OER electrocatalysts. Herein, we propose an anion regulation strategy, in which N-doped carbon nanotubes play a protective role by coating the Ni₃Fe alloy particles and two non-metallic elements S and Se are introduced to adjust the electronic structure, this can further help construct a heterogeneous surface, improve the valence state, and increase the hydrophilicity of the catalysts. The two as-prepared catalysts N-CNTs@NiS₂/Fe₇S₈ (overpotential of 330 mV to achieve 50 mA cm⁻² and Tafel slope of 51.49 mV dec⁻¹) and N-CNTs@NiSe₂/Fe₃Se₄ (360 mV and 72.32 mV dec⁻¹, respectively) exhibited considerably high OER activity in 1.0 M KOH solutions.