Photodeposition of catalyst nanoparticles for solar photoelectrochemical reactions: a sustainable fabrication technique.

Photocatalytic and photoelectrochemical phenomena are regarded as attractive options for converting solar energy into chemical energy: solar water splitting, photocatalytic reduction of CO2, water reformation, and CO2 conversion to biomass, all bear a significant impact in solving environmental issues. However, the fabrication of many promising semiconductor materials is in itself an expensive and energy-consuming process, that requires the development of sensibly sustainable techniques. Photodeposition of metal and metal oxide nanoparticles on semiconductor thin films can use solar energy for the electrically unassisted growth of catalyst nanoparticles onto existing photoelectrodes: the catalysts greatly improve the efficiency of the photoelectrodes by facilitating the separation of photogenerated charge carriers. In the present research, gold, platinum and ruthenium dioxide have been photodeposited on titanium dioxide thin films, while ruthenium dioxide has been photodeposited on hematite. Characterization and performances have been assessed, in order to report reliable and scalable processes for the sustainable growth of efficient catalysts.