Photoelectrocatalytic reduction of CO2 to methanol over the multi-functionalized TiO2 photocathodes

The photoelectrocatalytic (PEC) reduction of CO2 to chemical fuels was achieved by utilizing the multi-functionalized TiO2 film photocathodes. On the surfaces of TiO2 films, Pd nanoparticles were introduced to catch protons, molecules of Eosin Y disodium salt were embedded to absorb solar energy, and four different amine ligands were immobilized to capture and activate CO2. In the novel PEC cells, multi-functionalized TiO2 and Co-Pi/W:BiVO4 films were served as photocathode and the counter electrode, respectively. It was found that methanol was the major liquid product. Besides, some ethanol and acetone can be detected as well. The maximum formation rate and the highest selectivity of methanol were 43.6 μM cm−2 h−1 and approximately 100%, respectively. The Faradaic efficiencies of the PEC cells can exceed 1000% with the aid of photoelectrons. The 13CO2 labeling experiments verify that methanol and carbon monoxide are derived from CO2.