(216b) Computational Insights into Thermal and Photoresponse of Pd/C and Pd/N Co-Doped TiO2 using DFT

TiO₂ has attracted increasing attention during the past few decades as a promising catalytic and photocatalytic material due to its unique physicochemical properties. Specifically, in heterogeneous catalysis, it has been used as a catalytic material for treatment of environmental pollutants (greenhouse gases), photocatalytic reduction of CO₂ with water vapour and photodegradation of dyes. In recent years, doping of transition metal and nonmetal ions in TiO₂ has been reported to enhance the catalytic and photocatalytic performance of TiO₂. The main objective of this work is to study the effect of co-doping on the structure-property relationships of anatase TiO₂ using density functional theory (DFT+U) approach. Palladium ion and carbon (C)/Nitrogen (N) were co-doped in TiO₂ bulk and surface (001) and (100) planes in order to investigate the thermal and photoresponse of TiO₂. Differential bond length formations and associated net oxygen activations (NOA) were determined for the bulk and surface exposed Pd/C and Pd/N doped TiO₂. Effects of anion vacancies on the bond length distributions and net oxygen activations were found for the co-doped structures. NOA was found to be higher for Pd/N co-doped catalysts with 18.8 % and 28% in case of bulk and surface exposed codoped TiO₂ when compared to 17 % and 25 % in case of bulk and surface exposed Pd/C co-doped TiO₂. Band structure analyses were performed in order to examine the photoresponse of co-doped TiO₂. Band gaps obtained from the band structure analyses were in a range of 1.9-3 eV for Pd/C-doped TiO₂ whereas 2.7-3.1 eV for Pd/N-doped TiO₂, respectively, thereby establishing the importance of codoping for thermal and photocatalytic behaviour of TiO₂-based materials.