Photocatalytic Charging of Pt on TiO2 Activates O2
Materials that can activate oxygen are important due to the role of this process in a number of areas including energy conversion and environmental remediation. Oxygen activation involves the reduction of and dissociation of molecular oxygen into atomically adsorbed O species. A collaboration between the IMDC and the PartCat group at UNSW has shown that light pretreatment of Platinum-dressed TiO2 nanoparticles can boost catalytic oxygen activation. In an article published in ACS Catalysis recently, they have shown that light pretreatment for about 30 mins increased the Pt/TiO2 activity 8-fold compared to the untreated samples. Similar improvements were also observed for Pd/TiO2 systems.
Theoretical interpretation of this phenomenon by the IMDC team is based on the fact that absorption by TiO2 of UV photons generates electron charge carriers in the conduction band, which then migrate to the metal, effectively raising its Fermi level by charging it. The IMDC’s charge modulation DFT calculations reveal that when an O2 molecule adsorbs onto the charged metal, charge transfers into its antibonding orbitals, weakening its bonds and facilitating dissociation. Thus, photocatalytic charging of Pt on TiO2 activates O2 at the metal surface.
These findings are of importance for systems dependent on oxygen activation, where light pretreatment can provide facile and non-thermal means to promote catalyst performance.
More can be found here: https://doi.org/10.1021/acscatal.7b00700