Contribution of CuxO distribution, shape and ratio on TiO2nanotubes to improve methanol production from CO2photoelectroreduction

Many studies are focused on the development of materials for converting carbon dioxide into multicarbon oxygenates such as methanol and ethanol, because of their higher energy density and wider applicability. In this work, TiO(2)nanotubes (NT/TiO2) were modified with CuxO nanoparticles in order to investigate the contribution of different ratio of Cu2O/CuO and its distribution over NT/TiO(2)for CO(2)photoelectro-conversion to methanol. The photoelectrodes were built by anodization process to obtain NT/TiO(2)layer, and the decoration with CuxO hybrid system was carried out by electrodeposition process, using Na(2)SO(4)or acid lactic as electrolyte, followed by annealing at different temperatures. X-ray photoelectron spectroscopy analysis revealed the predominance of Cu(+1)and Cu(+2)at 150 degrees C and 300 degrees C, respectively. X-ray diffraction and scanning electron microscopy indicated that under lactic acid solution, the oxide nanoparticles exhibited small size, cubic shape, and uniform distribution on the nanotube wall. While under Na(2)SO(4)electrolyte, large nanoparticles with two different morphologies, octahedral and cubic shapes, were deposited on the top of the nanotubes. All modified electrodes converted CO(2)in methanol in different quantities, identified by gas chromatograph. However, the NT/TiO(2)modified with CuO/Cu2O (80:20) nanoparticles using lactic acid as electrolyte showed better performance in the CO(2)reduction to methanol (0.11 mmol L-1) in relation to the other electrodes. In all cases, a blend among the structures and nanoparticle morphologies were achieved and essential to create new site of reactions what improved the use of light irradiation, minimization of charge recombination rate and promoted high selectivity of products.