Integrating hydrogen production with selective methanol oxidation to value-added formate over a NiS bifunctional electrocatalyst

Abstract

The sluggish kinetics of oxygen evolution reaction (OER) severely limits the efficiency of the electrocatalytic water splitting to produce hydrogen. Therefore, an effective strategy is proposed to replace the OER with selective methanol oxidation reaction (MOR). A nickel sulfide nanosheet catalyst supported on Ni foam (NiS/NF) was prepared by a facile hydrothermal method following with sulfurization treatment. The as-obtained catalyst could be used for the co-electrolysis of methanol/water to produce hydrogen and value-added formate simultaneously. The electrocatalyst can selectively oxidize methanol to formate (1.36 V vs.RHE) and the energy consumption is significantly lower than OER. Furthermore, the integrated two-electrode electrolyzer drives 10 mA cm-2 at a cell voltage of 1.5 V with 96% Faradaic efficiency for MOR.