Directed Assembly of Cuprous Oxide Nanocatalyst for CO2 Reduction Coupled to Heterobinuclear ZrOCo Light Absorber in Mesoporous Silica

Abstract

Hierarchical assembly of an oxo-bridged binuclear ZrOCo light absorber unit coupled to a cuprous oxide nanocluster catalyst for CO2 reduction on mesoporous silica support is demonstrated. The proper positioning of the Cu oxide cluster was achieved by photodeposition of a [Cu(NCCH3)4]precursor by visible light excitation of the ZrOCo charge transfer chromophore, followed by mild calcination at 350 C. Illumination of the CuxOy-ZrOCo unit so formed in the presence of a diethylamine electron donor resulted in the reduction of surface Cu centers to Cu as demonstrated by the characteristic infrared band of adsorbed CO probe molecules at 2056 cm. For analogous CuxOy-TiOCo units, the oxidation state makeup of the surface Cu centers was dominated by Cu, and the Cu, Cu, and Cu composition was found to depend on the wavelength of MMCT excitation. The observed strong dependence of the CO2 photoreduction yield on the oxidation state of the surface Cu centers directly proves that CO2 is reduced on the CuxOy surface, thus establishing that the ZrOCo unit functions as light absorber, donating electrons to the CuxOy catalyst on whose surface CO2 is reduced. © 2015 American Chemical Society.