Strong hydrophilicity NiS/FeS heterojunctions encapsulated in N-doped carbon nanotubes for enhanced oxygen evolution reaction.

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 NiFe 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@NiS/FeS (overpotential of 330 mV to achieve 50 mA cm and Tafel slope of 51.49 mV dec) and N-CNTs@NiSe/FeSe (360 mV and 72.32 mV dec, respectively) exhibited considerably high OER activity in 1.0 M KOH solutions.