In situ construction of N-doped amorphous CoFe selenites toward efficient electrocatalytic water oxidation

The sluggish oxygen evolution reaction (OER) is considered as a major bottleneck for water splitting. It is critical to search for high performance of OER catalysts with different chemical compositions and structures. Herein, we report a new CoFe selenite with NH4+ cation, further, an amorphous N-doped CoFe selenite can be obtained by an environmentally friendly in situ-method, further, by adjusting the ratio of Co and Fe and calcination temperature, the optimal electrocatalyst shows the lowest overpotential of 242 mV at 10 mA cm−2 on glassy carbon and a small Tafel slope of 59.1 mV dec−1, respectively, besides, this catalyst maintains the current density of 10 mA/cm2 for at least 24 h when applying overpotential of 242 mV. N-doping into this CoFe selenites can tailor its electronic structure, moreover, its mesoporous structure favors the mass transfer, electrolyte diffusion and O2 release, in addition, the electrochemical oxidation processes can provide more active sites due to the surface modification of this CoFe selenites, consequently, exhibiting superior OER performance. This study provides an effective strategy to explore highly active and durable electrocatalysts for water splitting. [Display omitted] •An amorphous N-doped CoFe selenite was prepared via a facile in-situ N-engineering.•The optimal N-doped bimetallic CoFe selenite shows superior OER performance.•N doped into this CoFe Selenite could tailor its electronic structure.•The present study provides a strategy to explore new efficient OER electrocatalysts.