Engineering Cu₂O/Cu/N-C interface to induce directional migration of charge for driving photocatalytic homo-coupling of terminal alkynes

The efficient utilization of visible light catalysts for organic reactions necessitates not only the effective separation of photogenerated electrons and holes to participate in the reaction, but also their ability to form key intermediates with reactant molecules. The present study successfully synthesized a crusiform-like mesoporous structure of nitrogen-doped carbon-coated Cu₂O/Cu (Cu₂O/Cu/N-C) with a Cu₂O/dual electron acceptor interface using etched HKUST-1 as the precursor. A series of theoretical and experimental studies have demonstrated that the Cu₂O/Cu/N-C interface in the photocatalytic homo-coupling of terminal alkynes not only effectively enhances the separation of photogenerated electron−hole pairs, but also facilitates the formation of the key intermediate [Cu₂O/Cu/N-C]-phenylacetylide and promotes the rearrangement of its internal charges. As a result, the homo-coupling reaction can be effectively facilitated. The primary reason for the functional role of Cu₂O/Cu/N-C interface lies in the downward bending of energy band from Cu₂O to N-doped C layers, induced by the different work functions of Cu₂O, Cu and N-doped C layers. Consequently, Cu₂O/Cu/N-C photocatalysts demonstrate exceptional photocatalytic activity in the homo-coupling reaction of terminal alkynes under blue-light irradiation and air atmosphere. The present study presents a novel research methodology for the development of highly efficient visible light catalysts to facilitate organic reactions in future applications.