Promoted electro-oxidation kinetics in chromium-doped α‑Ni(OH)2 nanosheets for efficient selective conversion of methanol to formate

Abstract

Owing to the elusive pathways of methanol oxidation reaction (MOR) and the lack of applicable catalysts, the selective electro-oxidation of methanol to formate remains a challenging topic. Herein, we present a chromium-doping strategy to promote the MOR performance of α-Ni(OH)2 nanosheets with a high selectivity towards formate generation. Taking chromium-doped α-Ni(OH)2 nanosheets as an example, we further highlight the role of doping atoms in MOR by combining theoretical calculations with experimental measurements. It reveals that chromium doping can not only enhance the conductivity of α-Ni(OH)2 nanosheets, but also endow the catalyst with optimized kinetics for electroactive NiOOH formation and methanol absorption, thus resulting in a remarkable MOR current density of 141 mA cm−2 at 0.50 V vs. Ag/AgCl with a faradaic efficiency of 92.1% for formate. Furthermore, in situ infrared spectroscopy demonstrates that methanol is selectively oxidized to formate without further oxidation to CO2 over chromium-doped α‑Ni(OH)2 nanosheets in alkaline media.