Fabrication Of Modified Cuprous Oxide Materials And The Photoelectrocatalytic CO₂ Conversion To Solar Fuels

For the past two centuries, fossil fuels combustion results in enormous CO2 emission, leading to the serious environmental problem such as greenhouse effect. Meanwhile, energy crisis caused by the consumption of fossil fuels threats to the sustainable development of human beings. Thus, there is a large interest in developing the efficient recycling technology of CO2 from waste gas into hydrocarbon fuel and feedstock for the scientists all around the world. Considering the solar energy is a primary and inexhaustible energy source, developing appropriate photocatalysts, which convert solar energy into chemical energy, has been extensively studied.Cuprous oxide (Cu2O), which is inexpensive, nontoxic and easily prepared, has received great attentions in application of solar cells, photocatalysis, lithium ion batteries, and gas sensors. As a direct band gap semiconductor with a relatively narrow band gap of ca.1.9-2.2eV, it can absorb most of the visible light and is regarded as a potential photocatalyst. Herein, we prepared the TNTs/Cu2O composites and F-doped Cu2O films by electrodeposition method. They were characterized by SEM, XRD, XPS, UV-Vis and photoelectrochemical test. Finally,The CO2 conversion performance of the as-prepared catalysts is explored in the simulated sunlight illumination. The details are as follow:The TiO2 nanotube arrays (TNTs) were prepared by anodization method. Then the octahedral Cu2O nanoparticles were deposited on the TNTs, and the TNTs/Cu2O composites were successfully prepared. By changing the deposition time, the amount of the Cu2O nanoparticles could be controlled. When the deposition time was short, the main exposed crystal facet was (111) facet. With the deposition time increasing, the amount of Cu2O increased and the exposed crystal facet bacame (200) on account of the accumulation of Cu2O nanoparticles. In the AM 1.5 illumination of simulated sunlight, the TNTS/Cu2O showed the best performance and the main product was methane.By changing the deposition conditions, different Cu2O films were prepared and the best photoelectrochemical performance sample was obtained. After doping with F ion, the morphology of the Cu2O thin films showed little change. However, the F-doped Cu2O had better photoelectrocatalystic performance. The product analysis of CO2 PEC reduction was conducted, and the main hydrocarbon converted from CO2 was C2H4. It is found that the F-doped Cu2O with Cu/F=1:1 ratio performed best photoelectrocatalysis, and the sample with Cu/F=1:0.5 showed the highest faradic efficiency of CO2 to C2H4.