Engineering cuboctahedral N-doped C-coated p-CuO/n-TiO2 heterojunctions toward high-performance photocatalytic cross-dehydrogenative coupling

Abstract

The low separation efficiency of photogenerated electron–hole (e–h) pairs severely limits the activation of photocatalyts. One brilliant strategy is to construct a p–n type semiconductor heterojunction, which can establish an inner electric field to separate the e–h pairs with high efficiency. Here, for the first time, a cuboctahedral N-doped carbon-coated CuO/TiO₂ p–n heterojunction (CuO–TiO₂@N–C) was designed and fabricated successfully via direct calcination of a benzimidazole-modulated cuboctahedral HKUST-Cu with titanium-tetraisopropanolate absorbed inside concomitantly. Full structural characterizations incorporating DFT computations demonstrate that the CuO/TiO₂ p–n heterostructure can greatly boost the transport and separation of photoinduced e–h pairs. The nitrogen-doped carbon coating, with its excellent conductivity, porosity, stability and surface reaction activity, plays a pivotal role in promoting the overall performance and effectiveness of the reaction. The CuO–TiO₂@N–C displays significantly higher photocurrent density (0.042 μA cm⁻²) than the CuO@N–C (0.014 μA cm⁻²) and TiO₂@N–C (0.03 μA cm⁻²) electrodes, proving that the p–n heterojunction can improve the e–h generation efficiency. This unique photocatalyst affords superior photocatalytic efficiency, cycle stability and substrate scope towards cross-dehydrogenative coupling reactions.