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

Graphical A thorny challenge : A nanothorn-like superhydrophilic Nb−CoSe 2 /CC (CC=carbon cloth) catalyst is fabricated through a facile in-situ hydrothermal selenization and Ar annealing strategies. The catalyst illustrates an excellent oxygen evolution activity (297 mV at 200 mA cm −2 ), outstanding long-term durability, and good overall water splitting performance (1.93 V at 500 mA cm −2 ). 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−CoSe 2 /CC (CC=carbon cloth) structure was developed as an efficient OER catalyst. The optimized Nb−CoSe 2 /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−CoSe 2 /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−CoSe 2 /CC (anode) and the Pt/C (cathode). Density functional theory (DFT) calculations combined with experimental results revealed that incorporating niobium into the CoSe 2 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−CoSe 2 /CC resulting from the surface defects increased the surface wettability and facilitated reaction kinetics. These results indicate that Nb−CoSe 2 /CC intrinsically enhances OER performance and possesses potential practical water electrolysis applications.