Enhanced Physico-Chemical and Electrical Characteristics of Hydrothermally Synthesized NiTiO₃ via Tungsten Doping for Gas Sensing Applications

Herein, tungsten-doped nickel titanate (WNiTiO3) nanoparticles are synthesized using hydrothermal route and investigated physicochemical and gas sensing properties. The effect of W-dopant concentrations on the physicochemical and electrical characteristics of NiTiO3 is systematically investigated. X-ray diffraction analysis revealed a consistent decrease in crystallite size, accompanied by an increase in dislocation density and micro-strain with higher W doping levels. Optical study demonstrated significant band-gap narrowing (2.90 to 2.78 eV) due to tungsten incorporation. Fourier-transform infrared and Raman spectroscopies confirmed the W substitution at Ti sites. Surface morphology studies revealed the reductions in particle size and enhancements in the surface-to-volume ratio due to W doping. Thermo gravimetric analysis confirms enhanced thermal stability with increased W content. Electrical measurements show increased resistance in doped samples, which is indicative of charge carrier scattering and lattice distortion effects. Gas sensing analysis showed a significant improvement in H2S sensing performance with doping. The 10 mm W-doped NiTiO3 sensor exhibits the highest response of 88.66 at 250 °C for 100 ppm H2S, along with a rapid response (20 s), quick recovery (26 s) times, exceptional selectivity, and stable performance over 60 days, underscoring its potential for practical applications.