Artificial Photosynthesis of Alcohols by Multi‐Functionalized Semiconductor Photocathodes

Novel artificial photosynthesis systems are devised as cells of dye/Pd/NR-MOx (M = Ti, Zn)||Co-Pi/W:BiVO4 that convert efficiently CO2 to alcohols. The photocathodes are amino-functionalized, palladium deposited and in-situ sensitized nano-TiO2 or ZnO/FTO electrodes that are characterized by XPS, TEM, XRD, UV-vis spectra and determined by electrochemical techniques. The cell of dye/Pd/S-TiO2||Co-Pi/W:BiVO4 uniquely generates ethanol under irradiation of 200 mW/cm2, reaching 0.56 % light quantum efficiency (QE) at 0.56 V and 0.13 % QE without external electron supply. The cell of dye/Pd/N-ZnO||Co-Pi/W:BiVO4 solely produces methanol in a rate of 42.8 μM h-1 cm-2 at 0.56 V of a Si-solar cell, that is far less than the electrochemical voltage of water splitting (1.23 V). Its QE reaches to 0.38 % that is equal to plants. The isotopic labelling experiments confirm the carbon source and oxygen releasing. The selectivity for alcohols of multi-functionalized semiconductors is discussed.