Ultraviolet light-induced carbon defects on MOF-derived Ni@C greatly improved its electrocatalytic activity for hydrogen evolution

Abstract

Modulation of the d-band center of Ni to achieve an equilibrium between H-adsorption and H-desorption (H_ads/H_des) remains a great challenge. Herein, when Ni@C derived from MOFs was exposed to ultraviolet light, it was found that the sp² edge carbons were converted into sp³ defective carbons and further combined with the Ni clusters. Experimental studies and theoretical calculations confirmed that the enhanced d–p orbital hybridization between C and Ni promoted a large negative shift of the d-band center of Ni, which was in favor of improving the HER activity of the catalyst. As a result, the as-prepared UV-Ni@C/NF exhibited excellent HER activity in both alkaline aqueous solution (an overpotential of 309 mV at 1000 mA cm⁻²) and acidic aqueous solution (an overpotential of 446 mV at 1000 mA cm⁻²). This study indicated that the UV-illumination-induced defect method is a feasible strategy to precisely regulate the d-band center of Ni.