Niobium-Incorporated CoSe2 Nanothorns with Electronic Structural Alterations for Efficient Alkaline Oxygen Evolution Reaction at High Current Density.

Abstract

Developing cost-effective, highly active, and robust electrocatalysts for oxygen evolution reaction (OER) at high current density is a critical challenge in water electrolysis since the sluggish kinetics of the OER significantly impedes the energy conversion efficiency of overall water splitting. Here, a 1D nanothorn-like Nb-CoSe2 /CC (CC=carbon cloth) structure was developed as an efficient OER catalyst. The optimized Nb-CoSe2 /CC catalyst exhibited remarkable OER performance with the low overpotentials of 220 mV at 10 mA cm-2 and 297 mV 200 mA cm-2 and a small Tafel slope (54.1 mV dec-1 ) in 1.0 m KOH electrolyte. More importantly, the Nb-CoSe2 /CC electrode displayed superior stability after 60 h of continuous operation. In addition, cell voltages of 1.52 and 1.93 V were required to achieve 10 and 500 mA cm-2 for the electrolyzer made of Nb-CoSe2 /CC (anode) and the Pt/C (cathode). Density functional theory (DFT) calculations combined with experimental results revealed that incorporating niobium into the CoSe2 could optimize the adsorption free energy of the reaction intermediates and enhance the conductivity to improve the catalytic activity further. Additionally, the super-hydrophilicity of Nb-CoSe2 /CC resulting from the surface defects increased the surface wettability and facilitated reaction kinetics. These results indicate that Nb-CoSe2 /CC intrinsically enhances OER performance and possesses potential practical water electrolysis applications.