Comparative Catalytic and Photocatalytic Reduction of NO₃^- by the in Situ Generated Solar H₂ over Pt-Cu/TiO₂ Catalysts

Studies on the nitrate reduction reaction have shown that the bimetallic catalysts may be more efficient compared to the monometallic ones. To reduce nitrate, it is necessary to activate the precious metal by addition of a promoting second metal. Some studies have pointed out the relevance of the structure and geometry of the metal particles in the final mechanism of nitrate reduction. Well-defined nanoparticles could be used to catalyze structure-sensitive reactions with practical importance (pollution control).

Our investigation aimed to make deeper insight into NO₃^- catalytic reduction and photocatalytic reduction mechanisms. Two types of Pt-Cu supported on TiO₂ materials were employed in order to study the nitrate removal from aqueous phase and the ability of obtaining and using the in situ generated solar H₂ as reducing agent. The prepared catalysts were characterized and tested in photocatalytic/catalytic reduction of nitrate in aqueous solution in water splitting reaction. A correlation between the catalytic/photocatalytic performances of the supported Pt-Cu catalysts and their associated physicochemical and adsorption properties has been made. The catalysts activity for the nitrate reduction can be directly related to the interactions between platinum and copper. Deposition with Pt nanoparticles was found to contribute to enhance the photocatalytic activity toward H₂ production from aqueous solution. Our future research aims at optimizing the photocatalytic system having as future possible applications for hydrogen production using sunlight and water as the hydrogen source.