Vanadium-regulated nickel phosphide nanosheets for electrocatalytic sulfion upgrading and hydrogen production

Abstract

Electrochemical sulfion oxidation reaction (SOR) is highly desirable to treat sulfion-rich wastewater and achieve energy-saving hydrogen production when coupling with cathodic hydrogen evolution reaction (HER). Herein, we propose a thermodynamically favorable SOR to couple with HER, and develop vanadium-doped nickel phosphide (V-Ni2P) nanosheets for simultaneous achieving energy-efficient hydrogen production and sulfur recovery. The V doping can efficiently adjust electronic structure and improve intrinsic activity of Ni2P, which exhibits outstanding electrocatalytic performances for HER and SOR with low potentials of -0.093 and 0.313 V to afford 10 mA cm-2. Remarkably, the assembled V-Ni2P-based hybrid water electrolyzer coupling HER with SOR requires small cell voltages of 0.389 and 0.834 V at 10 and 300 mA cm-2, lower than these required in the traditional water electrolysis system (1.5 and 1.969 V), realizing low-cost sulfion upgrading to value-added sulfur and hydrogen generation. This work provides an approach for energy-saving hydrogen production and toxic waste degradation.