Cu-Ce Bimetallic Metal-Organic Framework-Derived, Oxygen Vacancy-Boosted Visible Light-Active Cu2O-CeO2/C Heterojunction: An Efficient Photocatalyst for the Sonogashira Coupling Reaction.

Abstract

The development of an economical transition metal-based catalyst for photocatalytic carbon-carbon coupling reactions is aspiring. Herein, a Cu-Ce metal-organic framework (MOF) was synthesized and carbonized to produce bimetallic Cu2O-CeO2/C, which was utilized in the Sonogashira cross-coupling reaction. The defects and oxygen vacancies in the catalyst were characterized by X-ray photoelectron spectroscopy and Raman spectroscopy, while the nature of Cu was characterized by H2-TPR analysis. The defect-induced MOF-derived Cu-Ce heterojunction created more oxygen vacancies (OV) in CeO2, revealing the high photocatalytic activity. The Cu-Ce heterojunction (Cu2O-CeO2/C) formed a Cu(I)-phenylacetylide active complex and exhibited higher catalytic activity for the visible light-induced Sonogashira cross-coupling reaction. 25%Cu2O-CeO2/C offered 93.8% phenylacetylene conversion with a 94.2% Sonogashira product selectivity by using household light-emitting diodes. No discernible activity loss was observed from the recycling of the catalyst. Based on catalytic activity, control reactions, and physicochemical and optoelectronic characterization, the structure-activity relationship was established and a reaction mechanism was proposed. Replacement of the costly Pd metal-based catalyst with a cheap Cu2O-CeO2-based catalyst for the synthesis of commercially important compounds with a sustainable visible light-induced catalytic process will be highly attractive to chemists and industrialists.