Ultrathin nickel sulfide nanosheets for sulfur ion electrooxidation assisted acetonitrile electroreduction

Electrochemical reduction of acetonitrile (ACN) to ethylamine (ETA) is a new strategy for producing high-value chemicals. Herein, the ultrathin nickel sulfide nanosheets (Ni_xS_y NSs) anchored on nickel foam (NF) nanohybrid (Ni_xS_y NSs/NF) were designed as an efficient bifunctional electrocatalyst for the waste conversion. Owing to the introduction of the S element, the ultrathin nanosheet structure, and the three-dimensional architecture, Ni_xS_y NSs/NF simultaneously reveals excellent electrocatalytic activity for both electrochemical ACN reduction reaction (EACNRR) at the cathode and electrochemical sulfur ion (S²⁻) oxidation reaction (ESOR) at the anode. For the EACNRR, Ni_xS_y NSs/NF exhibits a Faradaic efficiency of 95.5% and the ETA yield of 923.1 mmol h⁻¹ g⁻¹ at −0.05 V potential. For the ESOR, the S²⁻ ion is oxidized to the value-added S₈ product, in which the oxidation potential is only 0.16 V at 50 mA cm⁻². Consequently, the assembled Ni_xS_y NSs/NF∥Ni_xS_y NSs/NF electrolytic cell is successfully established for the ESOR-assisted EACNRR system that only needs a cell voltage of 0.32 V to reach the 50 mA cm⁻² current density. This work provides an effective and energy-saving strategy for the co-production of value-added chemicals from pollutants.