Rational Design of Ni³⁺-Rich Nickel Nitride Enables Paired Electrooxidation of Sterol and Hydrogen Evolution in a...

Electrooxidation of sterols is recognized as a promising approach for synthesizing value-added steroid hormone pharmaceuticals. However, enhancing current density while delivering market-required steroidal carbonyl products with high selectivity remains a significant challenge. Herein, we report a rational design of Ni³⁺-rich active sites on nickel nitride (Ni₃N) nanosheets via Pd-induced electronic modulation, which is utilized for sterol oxidation coupled with hydrogen evolution reaction (HER). Experimental and theoretical analyses demonstrated that the strong electron-withdrawing capability of Pd acts as an "electron pump," accelerating the formation of high-valent Ni³⁺ active centers by attracting electrons from Ni₃N to Pd, facilitating the adsorption and activation of N-(1-hydroxy-2,2,6,6-tetramethylpiperidin-4-yl)acetamide (ACTH) during the oxidation process, thereby enhancing catalytic activity. The Pd-Ni₃N composite as a bifunctional electrocatalyst for producing carbonyl product 1b (19-Hydroxy-4-androstene-3,17-dione) and H₂ concurrently at an industrial-scale current of 5 A in a large flow electrolyzer, achieving productivities of 70.9 mmol/h for 1b (with 99% selectivity) and 93.1 mmol/h for H₂. This work provides a novel strategy for the electrosynthesis of valuable steroid intermediates alongside H₂ production.