Visible-light-driven CO2 reduction and H2 evolution boosted by 1D Cu2O/CuO heterostructures

Abstract

The CO2 reduction reaction (CO2RR) offers an efficient path to the neutral carbon cycle and clean energy storage. For this reaction, 1D copper oxides (CuxO) are promising photocatalyst since promote an efficient charge transfer, suppress the photocorrosion, and provide active sites for CO2 adsorption. Therefore, in this work, 1D Cu2O/CuO heterostructures were manufactured by thermal oxidation of a copper mesh. This method works at atmospheric pressure, it is scalable, and it has a high yield, in a view of large-scale production. The copper mesh, a 3D metal skeleton, was selected as the substrate due to good light diffusion, low cost, and easy application. The characterization carried out made it possible to identify a homogeneous growth of the 1D Cu2O/CuO nanoneedles, which presented adequate band gaps for their activation with visible light and a stable photocurrent. These properties favored the CO2RR to solar fuels: HCOOH, CH3OH, HCOH, CH4, and CH3CH2OH. Furthermore, the samples exhibited activity for H2 evolution from H2O splitting. In this reaction, the heterostructures suffer photocorrosion of CuO to Cu2O, which competes for the electrons photogenerated during the reaction. However, this phenomenon was effectively suppressed by the addition of the CO2RR products and seawater as sacrificial agents. In general, the productions obtained from both reactions were up to 45% higher than the reference, which was attributed to the efficient transport of charges in the 1D architectures, the affinity for CO2, and its homogeneous exposure.