On the behavior of modified TiO2 nanotubes for a photoanode-driven photoelectrochemical reduction of CO2

Carbon dioxide is one of the main greenhouse gases responsible for global warming. Due to the high costs of its disposal, many efforts have recently been addressed to its reuse: converting CO2 to valuable compounds allows considering it as a feedstock, rather than a waste product. Photoelectrochemical reduction represents one of the possible alternatives to the chemical oxidation, which may be considered “green” when solar energy and water are used to drive the process, like in natural photosynthesis. Different system configurations and experimental conditions are needed, depending on the use of photosensitive material as cathode, anode or both in the photoelectrochemical (PEC) cell. In the present paper the possibility to use a photoanode-driven PEC cell is investigated, in which the anode material is composed by a nanotubular structure of TiO2, while metals or metal composite oxides are used as cathode. Phoelectrosplitting of water was already tested at this kind of anode, but a nominal 1cm2 of active surface was used in the previous cases. In the present work a scale up of the system has been made to obtain electrodes of 15cm2, and the photocatalytic performance was improved by deposition of tungsten oxide