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

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 mu mol 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.