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.