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

Abstract

Modulation of d-band center of Ni to achieve an equilibrium between H-adsorption and Hdesorption (H ads /H des ) remains a great challenge. Herein, Ni@C derived from MOFs was treated by ultraviolet light. It was found that sp 2 edge carbon were converted to sp 3 defective carbon and further combined with Ni clusters. Experimental and theoretical calculations confirmed that the enhanced d-p orbital hybridization between C-Ni promoted a large negative shift of the dband center of Ni, which was in favor of improving the HER activity of the catalyst. Moreover, the core-shell structure of carbon-coated Ni effectively protected the Ni sites and improved its catalytic stability when applied in electrocatalytic water splitting. As a result, as-prepared UV-Ni@C/NF exhibited excellent HER activity in both alkaline aqueous solution (overpotential of 309 mV at 1000 mA cm -2 ) and acidic aqueous solution (overpotential of 446 mV at 1000 mA cm -2 ). This study indicated the UV-illumination-induced defects method as a feasible strategy to precisely regulate the d-band center of Ni.