Integrating Hydrogen Production with Aqueous Selective Semi‐Dehydrogenation of Tetrahydroisoquinolines over a Ni2P Bifunctional Electrode

Exploring an alternative anodic reaction to produce value‐added chemicals with high selectivity, especially integrated with promoted hydrogen generation, is desirable. Herein, a selective semi‐dehydrogenation of tetrahydroisoquinolines (THIQs) is demonstrated to replace the oxygen evolution reaction (OER) for boosting H₂ evolution reaction (HER) in water over a Ni₂P nanosheet electrode. The value‐added semi‐dehydrogenation products, dihydroisoquinolines (DHIQs), can be selectively obtained with high yields at the anode. The controllable semi‐dehydrogenation is attributed to the in situ formed Ni^II/Ni^III redox active species. Such a strategy can deliver a variety of DHIQs bearing electron‐withdrawing/donating groups in good yields and excellent selectivities, and can be applied to gram‐scale synthesis. A two‐electrode Ni₂P bifunctional electrolyzer can produce both H₂ and DHIQs with robust stability and high Faradaic efficiencies at a much lower cell voltage than that of overall water splitting.