In-situ grown nanocrystal TiO2 on 2D Ti3C2 nanosheets for artificial photosynthesis of chemical fuels

Artificial photosynthesis of high-valued chemicals is a promising route to alleviate global warming and energy crisis. Herein, a layered hybrid heterojunction of TiO2/Ti3C2 was synthesized by a facile hydrothermal oxidation method. The TiO2/Ti3C2 heterojunction was further functionalized by imine ligands and Pd nanoparticles, and used as a photocathode in CO2 reduction for the first time. These layered TiO2/Ti3C2 heterojunction materials have narrow band gap (2.1 eV), which contributes to the absorption of visible light. In the artificial photosynthetic cell of Pd/N-TiO2/Ti3C2 parallel to BiVO4, some hydrocarbon, such as formate, methanol and ethanol, were generated efficiently. The evolution rate of total hydrocarbon was as high as 73.6 mu M cm(-2) h(-1) (36.8 mM h(-1) g(-1)). The hydrogen gas can be evolved in the photoelectrocatalysis cell when the external voltage provided by Si solar cell is as low as - 0.4 V, due to the high activity of the heterojunction structure. The highest apparent light quantum efficiency of artificial photosynthesis cell was 1.78% at - 1.0 V. The carbon source of products was derived from CO2, which was verified by (CO2)-C-13 labeling experiments. The experimental results suggest that the in-situ formed TiO2/Ti3C2 heterojunction materials can be employed as candidates for efficiently photoelectrocatalytic reduction of CO2 to chemical fuels.