Vapor-phase hydrothermal growth of single crystalline NiS2 nanostructure film on carbon fiber cloth for electrocatalytic oxidation of alcohols to ketones and simultaneous H2 evolution

Electrocatalytic synthesis of value-added chemicals is attracting significant research attention owing to its mild reaction conditions, environmental benignity, and potentially scalable application to organic synthetic chemistry. Herein, we report the preparation of a single-crystalline NiS2 nanostructure film of ∼ 50 nm thickness grown directly on a carbon fiber cloth (NiS2/CFC) by a facile vapor-phase hydrothermal (VPH) method. NiS2/CFC as an electrocatalyst exhibits activity for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in alkaline media. Furthermore, a series of alcohols (2-propanol, 2-butanol, 2-pentanol, and cyclohexanol) were electrocatalytically converted to the corresponding ketones with high selectivity, efficiency, and durability using the NiS2/CFC electrode in alkaline media. In the presence of 0.45 M alcohol, a remarkably decreased overpotential (∼ 150 mV, vs. RHE) at the NiS2/CFC anode compared with that for water oxidation to generate O2, i.e., the OER, in alkaline media leads to significantly improved H2 generation. For instance, the H2 generation rate in the presence of 0.45 M 2-propanol is almost 1.2-times of that obtained for pure water splitting, but in a system that employs an applied voltage at least 280 mV lower than that required for water splitting to achieve the same current density (20 mA·cm–2). Thus, our results demonstrate the applicability of our bifunctional non-precious-metal electrocatalyst for organic synthesis and simultaneous H2 production.