Enhancing solar-driven photoelectrocatalytic efficiency of Au nanoparticles with defect-rich hydrogenated TiO2 toward ethanol oxidation

Abstract

It is significant to promote the efficiency of solar fuel cells via improving the utilization of solar in photoelectrocatalysis. In this work, hydrogenated TiO2 (H-TiO2) nanoparticles with Ti3+ and/or oxygen vacancy (VO) defects were obtained and have extended light absorption to visible light region. As a photochemical component, H-TiO2 was further coupled with Au nanoparticles to assemble photoelectrocatalyst to apply in photo-assisted electrooxidation of ethanol. Due to the existence of defects in H-TiO2, the peak current density on Au/H-TiO2 is improved by 5.4% with the assistance of light irradiation, and even up to 18.3% under simulated sunlight illumination, which is much higher than that on Au/W-TiO2 (W-TiO2 loaded Au) under the light irradiation. Meanwhile, it is demonstrated that the charge transfer is improved on Au/H-TiO2 with Vo due to the existence of Vo, improving the separation of excited electrons and holes. Density function theory (DFT) based theoretical calculations illustrate that the energy barrier of reaction intermediates on Au-TiO2 with Vo defects is lower than that without Vo, indicating that Au-TiO2 with Vo is more energetically favorable. This work highlights the possibility of using defective semiconductor nanomaterials to combine photocatalysis and electrocatalysis in solar fuel cells and to further improve the efficiency of fuel cells under solar full spectrum.