Iron and nitrogen Co-doped CoSe2 nanosheet arrays for robust electrocatalytic water oxidation

Abstract

Due to the low-carbon economy requirement in large-scale industrial applications, exploration of active, robust, resourceful, low-cost and efficient oxygen evolution reaction (OER) electrocatalysts is urgently needed. In this work, we report a Fe–N co-doped cobalt selenide nanosheet array (Fe–N–CoSe₂) on nickel foam (NF) as a highly efficient OER electrocatalyst via an anion and cation co-doping strategy using a metal–organic framework (MOF) as the precursor. The nanosheet arrays grown on NF without an additional binder are not only beneficial for accelerating the charge transfer, but also for suppressing electrocatalyst shedding. Furthermore, the nanosheet structure constructed using nanograins could promote electrolyte penetration and gas diffusion and increase the active sites. More importantly, the Fe and N element doping can further provide additional active sites, regulate the electronic structure and boost the OER kinetics. In view of the abovementioned points, the as-prepared Fe–N–CoSe₂ electrocatalyst exhibits outstanding OER performance and long-term durability. It affords a current density of 50 mA cm⁻² at a small overpotential of 270 mV with a Tafel slope of 62.7 mV dec⁻¹, and the Fe–N–CoSe₂ electrocatalyst has only a small attenuation of 1.9% after a 100 h constant test at 100 mA cm⁻² in alkaline solution, which is superior to the commercial RuO₂ electrode. These results offer a potential approach for the preparation of effective and robust OER electrocatalysts as substitutes to replace the expensive commercial electrocatalysts based on element doping.