Promotional Effect of Semiconductor-Supported Plasmonic Copper Nanoparticles in Visible-Light-Driven Photocatalytic Oxidative Homocoupling of Alkynes

Enhancing the oxidation resistance of copper nanoparticles (CuNPs) is a crucial objective in plasmonic photocatalytic reactions. In this study, a series of Cu/X catalysts was synthesized using semiconductor nanomaterials (X = TiO2, ZnO, BN, TiN, SiC, and C3N4) as supports for CuNPs. These catalysts were systematically evaluated in visible-light-driven photocatalytic oxidative homocoupling of phenylacetylene (OHA). Comprehensive characterization revealed distinct metal-support interactions and nanostructure evolution during repeated catalytic cycles. The photocatalytic performance, copper leaching, and structural stability of the catalysts were compared. Cu/TiO2 achieved the highest 1,3-diyne yield (up to 93%) in the first two cycles. In contrast, Cu/ZnO showed minimal copper leaching and excellent recyclability, retaining high activity over three consecutive cycles without the need for reduction pretreatment. Comparative studies revealed that the combination of localized surface plasmon resonance (LSPR) and efficient electron transfer within the Cu0-Cu2O-CuO composite was a key factor in enhancing the photocatalytic activity and stability. These findings provide new insights into the rational design of durable CuNP-based photocatalysts for visible-light-driven organic transformations.