Designing effective, robust, and low-cost catalysts for oxygen evolution reaction (OER) is an urgent requirement yet challenging task in water electrolysis. In this study, a NiCoP-nanocubes-decorated CoSe 2 nanowires arrays three-dimensional/two-dimensional (3D/2D) electrocatalyst (NiCoP-CoSe 2 -2) was developed for catalyzing OER via a combined selenylation, co-precipitation, and phosphorization method. The as-obtained NiCoP-CoSe 2 -2 3D/2D electrocatalyst exhibits a low overpotential of 202 mV at 10 mA cm −2 with a small Tafel slope of 55.6 mV dec −1 , which is superior to most of reported CoSe 2 and NiCoP-based heterogeneous electrocatalysts. Experimental analyses and density functional theory (DFT) calculations proof that the interfacial coupling and synergy between CoSe 2 nanowires and NiCoP nanocubes are not only beneficial to strengthen the charge transfer ability and accelerate reaction kinetics, but also facilitate the optimization of interfacial electronic structure, thereby enhancing the OER property of NiCoP-CoSe 2 -2. This study offers insights for the investigation and construction of transition metal phosphide/selenide heterogeneous electrocatalyst toward OER in alkaline media and broadens the prospect of industrial applications in energy storage and conversion fields.
The development of highly active, durable and earth-abundant electrocatalysts toward hydrogen evolution reaction (HER) is of great significance for promoting hydrogen energy . As one of the most potential substitutes for Pt-based materials, pyrite cobalt selenide (CoSe 2 ) still has shortcomings in terms of HER performance possibly due to its unfavorable hydrogen adsorption characteristics. Metal cation doping has been considered as one of the most available methods to modulate the electronic structure of electrocatalysts. Herein, non-transition metal tin (Sn) doped CoSe 2 nanowire arrays grown on carbon cloth have been constructed and fabricated via a simple gas-phase selenization treatment of hydroxide precursor. The successful doping of Sn element into CoSe 2 nanowires was confirmed by many experimental results. The as-prepared catalyst shows an obviously enhanced HER performance in alkaline media . Compared with pristine CoSe 2 , the overpotential of Sn doped catalyst with optimal doping content decreases from 189 mV to 117 mV at 10 mA cm −2 and the Tafel slope declines from 94 mV dec −1 to 86 mV dec −1 , as well as shows long-term durability for 100 h. Experimental results and further density functional theory (DFT) calculations show that Sn doping can improve the ability of charge transfer and increase the electrochemical surface area, as well as optimize the hydrogen adsorption energy , all of which are instrumental in HER performance improvement. This work not only provides atomic-level insight into regulating the electronic structure of transition metal selenides by main group metal doping, but also broadens the avenue of developing high-efficiency and stable non-precious metal catalysts .
Cobalt diselenide (CoSe2) is considered a promising catalyst for hydrogen evolution reaction (HER); however, the limited active number, agglomeration, and quick deactivation by acid etching hinder its broad adoption. Herein, we report carbon layer-covered CoSe2 nanowire arrays grown on carbon cloth (C@CoSe2/CC). The structure of the nanowire array demonstrates synergistic effects in promoting the infiltration of electrolytes, accelerating the diffusion of H2 bubbles, and preventing CoSe2 from being etched by the electrolyte. Consequently, the overpotential and Tafel slope (193 mV, 54.3 mV dec−1) obtained sustained 24 h with a negligible overpotential deterioration. This study provides insights into optimizing the intrinsic activity of active sites.
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