Electrocatalytic hydrogenation of quinoxaline using CoO/NF in organic molecular redox flow batteries

Abstract

To advance the application of liquid organic hydrogen carriers (LOHCs) in flow batteries, the mechanism and performance of CoO/NF for the electrocatalytic hydrogenation (ECH) of quinoxaline—prepared by a low-melting-point ionic liquid electrodeposition method—are systematically investigated. The quinoxaline/tetrahydroquinoxaline conversion reaction catalyzed with CoO/NF results in superior ECH activity with low charge transfer impedance (1.624 ohm) and a Tafel slope of 103 mV dec⁻¹; the efficiency of quinoxaline conversion is 99.84%, and the selectivity of tetrahydroquinoxaline formation is 98.73%. The hydrogen in the hydrogenation reaction comes from water, and the active hydrogen atoms (H*) generated on the cobalt surface via the Volmer step are the key intermediates. The electrocatalyzed quinoxaline/tetrahydroquinoxaline reaction is an efficient system for hydrogen storage in flow batteries, providing a scientific basis for hydrogen energy storage and conversion in LOHC-based flow batteries.