Carbon nitride thin-film planar heterojunctions for photoelectrocatalytic C–N coupling

Transitioning traditional chemical processes into a more sustainable, low carbon impact model is of utmost priority to mitigate the pressing issue of global environmental change. Photoelectrocatalysis, which combines photocatalysis and electrocatalysis to further lower energy consumption and to engage on challenging chemicals, is a viable and powerful solution. Here, we introduce a strategy to stabilize and enhance the reactivity of carbon nitride thin-film-based photoelectrodes by introducing a conductive layer in between the thin film and its substrate to form a planar heterojunction electrode. The as-prepared photoelectrodes were fabricated and applied for the oxidation of benzylamine with high selectivity towards N-benzylideneamine and improved reusability. Furthermore, we expanded the scope of reactions to prepare the more synthetically challenging and pharmaceutically relevant 3,6-diphenylpyridazines from 1,4-diphenylbutane-1,4-dione. The results indicated that the CN thin-film-based photoelectrodes demonstrated excellent performances with good selectivity toward oxidation products, using only less than 1 mg of carbon nitride catalyst, achieved by effective engineering of the interfaces.