Adsorption of CO molecules on anatase TiO2(001) loaded with noble metals M (M = Ir/Pd/Pt): A study from DFT calculations

Abstract

The structure and electronic behaviour of anatase TiO2(001) surface loaded with noble metal atoms M (Ir, Pd and Pt) are systematically investigated by first-principles calculations. Meanwhile, the adsorption behaviour of CO on M-loaded anatase TiO2 is also studied. The results show that Ir and Pt atoms are more likely to be adsorbed on the O2 C (T1) site, while Pd atom is more easily adsorbed at the Ti5 C (T3) site. Among all of the considered systems, the formation energy of Pd/TiO2 (−2.500 eV) is the lowest one followed with Pt/TiO2 (−4.552 eV) and Ir/TiO2 (−6.298 eV). The adsorption mechanism of CO on the anatase TiO2(001) surface is studied by choosing the most stable configurations. The order of adsorption energy is CO/TiO2 (−1.065 eV) >CO/Pd/TiO2 (−2.535 eV) >CO/Pt/TiO2 (−3.326 eV) >CO/Ir/TiO2 (−3.593 eV). This theoretical study shows the adsorption mechanism of CO on the anatase TiO2(001) and provides guidelines for further exploring the adsorption material with excellent adsorption capacity.