Transition metal oxide based TiO₂ nanoparticles for visible light induced CO₂ photoreduction

The development of nanostructured visible light photocatalytic systems capable of harnessing the energy from the sun is imperative for producing carbon based fuels and chemicals. V-, Cr- and Co-TiO₂ photocatalysts immobilized onto quartz plates were successfully prepared by sol–gel method, investigated as a function of metal concentration and tested for visible light induced CO₂ reduction for the first time. Results established that introduction of these metal ions into the host framework not only modified the crystallinity of TiO₂, but influenced its light absorption properties as well. Enhanced bathochromic shift from the UV region to longer wavelengths in the visible light region was observed with increasing metal concentrations for all samples especially Cr. The photoconversion rates were remarkably enhanced by the metal doped TiO₂ supports when compared to pure TiO₂, with the Co-TiO₂ samples having the highest photoconversion rates.