Influence of Pt-loading on the energy band gap and gas sensing of titanium perovskite

Nickel titanate (NiTiO3) and zinc titanate (ZnTiO3) perovskite nanostructures were fabricated via a facile microwave-assisted hydrothermal method, followed by loading 1 wt% of Pt using a precipitation method to obtain Pt–NiTiO3 and Pt–ZnTiO3. Scanning electron microscope revealed a tube-like arrangement of the NiTiO3 nanoparticles and a porous network of ZnTiO3 nanoparticles. X-ray powder diffraction confirmed the single-phase ilmenite structure of both NiTiO3 and ZnTiO3 nanoparticles, which was further preserved after Pt-loading. UV–Vis diffused reflectance, photoelectron yield, and photoluminescence as well as the x-ray photoelectron spectroscopy analyses provided insight into the energy band gap, ionization energy, and the type of defects present in the synthesized titania perovskites. The gas sensing results revealed that Pt-loading enhanced the sensitivity and induced Pt–NiTiO3 selective detection of NO2 among the other tested corrosive gases, such as CO2, and SO2. This improvement was justified by the synergetic contribution of the catalytic ability of both Pt and NiTiO3 as well as the metal/semiconductor heterojunction leading to improved NO2 adsorption.