Effect of excitation energy on the activity for CO 2 reduction to CO of Ag / Ga 2 O 3 photocatalysts

The influence of excitation photon energy on the CO2 reduction activity of Ag/Ga2O3 was investigated by using several optical filters. The band gap excitation of Ga2O3 was necessary for this reaction and the CO selectivity differed depending on the kind of filter. It was revealed that Ag nanoparticles grow during reaction and the particle size was different with each filter. CO selectivity depended on not only the size of Ag nanoparticles but also excitation photon energy. The highest CO selectivity was obtained by using photons filtered by 33U for a 230-420 nm wavelength range.