Engineering the Cu2O–reduced graphene oxide interface to enhance photocatalytic degradation of organic pollutants under visible light.

In this work, Cu 2 O–reduced graphene oxide (rGO) composites were synthesized with tunable Cu 2 O crystal facets ({1 1 1}, {1 1 0} and {1 0 0} facets). The degradation performance of methylene blue under visible light was ranked: o-Cu 2 O{1 1 1}–rGO > d-Cu 2 O{1 1 0}–rGO > c-Cu 2 O{1 0 0}–rGO. UV–vis diffuse reflectance and photoluminescence spectra showed that o-Cu 2 O–rGO exhibited the enhanced visible-light absorption and the faster charge-transfer rate. Furthermore, X-ray photoelectron spectroscopy and Raman characterizations showed that o-Cu 2 O–rGO was beneficial for the stabilization of Cu + species and the formation of oxygen defects. With the help of in-situ electron spin resonance (ESR), more superoxide radicals were detected over o-Cu 2 O–rGO, which promoted organic pollutants degradation. The above results confirmed that the catalytic behaviors of three Cu 2 O–rGO composites were related to the electronic structures and interfacial connections. The o-Cu 2 O{1 1 1}–rGO displayed the superior performance, for the highly-active coordinated unsaturated Cu and the intensive interfacial connection, which was beneficial for the rapid the photo-generated electron transfer and the formed active superoxide species. This study showed that engineering the interfacial structures could provide a scientific basis for the design of efficient photo-catalysts. [ABSTRACT FROM AUTHOR]