Synergistic modulation of NiSe2 by doping with chromium and nitrogen for high-efficiency overall water splitting

Designing high-efficiency bifunctional catalysts for alkaline water splitting is well anticipated, but is a considerable challenge owing to sluggish kinetics of hydrogen/oxygen evolution reaction (HER/OER). Herein, chromium and nitrogen co-doped nickel selenide nanosheet arrays supported on nickel foam (Cr–NiSe2–N/NF) are rationally devised as an effective bifunctional electrocatalyst through an anion and cation dual-doping approach for overall water splitting. The as-obtained electrocatalysts displayed eminent catalytic performance for both OER (η10 = 222 mV, η50 = 310 mV) and HER (η10 = 123 mV, η100 = 256 mV) in 1 M KOH resolution. Furthermore, the Cr–NiSe2–N/NF as a bifunctional electrocatalyst only requires 1.59 V cell voltages at 10 mA cm−2 and exhibits excellent durability of 50 h. Experimental analyses and density functional theory (DFT) calculations prove that the simultaneous introduction Cr and N into NiSe2 could synergistically adjust the electronic configuration and upshift the transition metal d-band center, which facilitates the enhancement of the adsorption capabilities towards reaction intermediates of HER and OER, thus enhancing catalytic activities. This work affords an efficient strategy for NiSe2-based electrocatalysts to improve electrocatalytic performance and motivates further research to construct highly active bifunctional electrocatalysts.