Process intensification enhanced continuous flow for the effective coupling of sterol electrooxidation with H2 evolution using NiMo-based electrocatalysts

The electrocatalytic oxidation (ECO) of steroid alcohols at the anode is sustainable approach to synthesize valuable steroid carbonyls. This process is coupled with the hydrogen evolution reaction (HER) occurring at the cathode, further enhancing its environmental benefits. However, determining compatible electrocatalysts facilitating production of steroid carbonyls and hydrogen poses challenge. Hence, synergistically enhanced electro-catalytic approach was proposed, whereby NiMoO4 and the aminoxyl radical mediator 4-acetamido-TEMPO (ACT) were used together at the anode, in combination with Ni0.2Mo0.8N at the cathode. In situ experiments and theoretical calculations revealed that the introduction of Mo facilitates the formation of NiOOH and provides stabilization of ACTH (the reduced form of ACT) on the NiMoO4 surface. The effect of Mo also contributed to avoid the H* over-binding to decrease the HER energy barrier. This study aims to establish systematic approach towards the rational design of electrocatalysts that can be used to produce value-added steroid carbonyls and H2.