Synthesis of sub-nanometric Cu2O catalysts for Pd-free C–C coupling reactions

Abstract

We report a facile solution-phase sonochemical route for the glucose-template mediated synthesis of Cu₂O nanocrystals with well-defined sizes and shapes. This approach offers a superficial and cost-effective route for the synthesis of Cu₂O nanocrystals. The formation of different nanostructures (i.e., stars, cubes, and octahedra) was tuned by varying the reaction conditions as well as the concentration of template. The morphology-controlled Cu₂O nanocrystals show high activity for the external base-free Ullmann homocoupling reactions of aryl halides. 61.6% conversion of chlorobenzene was achieved over octagonal Cu₂O nanocrystals with a turn-over-frequency (TOF) as high as 1696 h⁻¹. This result demonstrates that the size and shape-dependent properties of Cu₂O nanocrystals are critical to the activity of aryl halide and highlights the importance of shape engineering in the design and development of an efficient catalyst for the Ullmann reaction.