مشخصات پژوهش

Using density functional theory (DFT) calculations, we predict the SOx sensing performance of heterostructured TiO2/ZnO nanocomposites with and without nitrogen doping. The interaction of SO2 and SO3 molecules with the considered nanocomposites were examined based on different orientations of the gas molecules towards the nanocomposite. The fivefold coordinated titanium atoms were found to be the binding sites on the TiO2 side of nanocomposite, whereas, on the ZnO side, the oxygen atom acts as a binding site. Our theoretical results demonstrate that the interaction of SOx molecules with N-doped nanocomposites is more energetically favorable than that with undoped ones, indicating that N-doped TiO2/ZnO nanocomposites show stronger chemisorption and greater electron transfer effects than undoped TiO2/ZnO. The electronic properties of the adsorption systems were investigated in terms of the projected density of states and molecular orbitals. After the adsorption process, all S–O bonds of the SOx molecules were elongated, which is probably attributed the electron density transfer from the S–O bonds to the newly formed bonds between the nanocomposite and SOx molecules. The charge transfer analysis revealed that N-doped nanocomposite acts as a donor. The N-doped nanocomposite induce dramatic changes of electronic properties of TiO2/ZnO, which can be useful feature for improving the gas sensing performance. Our calculation results aim to provide some information for future experiment.