The photoelectric catalytic reduction of CO2 to methanol on CdSeTe NSs/TiO2 NTs

Abstract

The CdSeTe nanosheet (CdSeTe NS)/TiO₂ nanotube (TiO₂ NT) photoelectrocatalyst was obtained by the hydrothermal method by loading CdSeTe NSs onto TiO₂ NTs which were prepared by an anodic oxidation method. The SEM and TEM results show that CdSeTe had a flaky structure with a large size of 300–400 nm and a small size of about 100 nm, which distributed on the TiO₂ NT surface uniformly. The HRTEM and XRD characterization revealed that the CdSeTe NSs grew along the (100) and (002) orientations. Measured by UV-vis DRS and XPS, the energy band gap of the TiO₂ NTs was narrowed from 3.20 eV to 1.48 eV by the introduction of the CdSeTe NSs, of which the conduction band and valence band are located at −0.46 eV and 1.02 eV, respectively. In the photoelectrocatalytic reduction CO₂ process, the current density had a significant improvement after the decoration with the CdSeTe NSs, increasing from 0.31 mA cm⁻² to 4.50 mA cm⁻² at −0.8 V. Methanol was the predominant photoelectrocatalytic reduction product identified by chromatography, and it reached 1166.77 μmol L⁻¹ after 5 h. In addition, the mechanism of the high efficiency photoelectrocatalytic reduction of CO₂ to methanol was explained from the following aspects: energy band matching, high efficiency electron transmission and the stability of the catalyst.