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

- Multi-functionalized TiO2 photocathodes were established for CO2 reduction with Co-Pi/W:BiVO4 film as counter electrode.
- In photocathode, Pd nanoparticles catch protons, dye absorbs solar energy, and amine ligands capture and activate CO2.
- The Faradaic efficiency of PEC cell exceeds 1000% due to the synergistic effect of photo- and electro-catalytic process.

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.

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