Influence of synthesis and optimization parameters on NO_x degradation performance of TiO₂ nanoparticles via sol-gel method

Systematic optimization of titanium dioxide (TiO₂) nanoparticles imparting the possibilities to enhance the environmental remediation through improved degradation of hazardous pollutants. This study examines the influence of sol-gel synthesis parameters such as calcination temperature (400–800 °C), acid catalysts, and pH levels (2–4) on the preparation of well optimized TiO₂ nanoparticles using titanium isopropoxide (TTIP). The systematic analyses revealed that the high photocatalytic performance strongly correlates with the phase purity, particle size, and surface area. The systematically optimized catalysts with a calcination temperature of 400 °C and pH of 2 exhibited pure anatase phase TiO₂ with a uniform crystallite size (11.5 nm) and bandgap energy of ∼3.16 eV. Calcination temperature and pH are essential factors that determine the crystal structure of TiO₂ and the efficacy of NO_x degradation. The higher calcination temperatures led to the formation of a rutile phase and significantly reduced the photocatalytic activity. The optimized TiO₂ exhibited an enhanced NO_x degradation efficiency of 49 %, outperforming commercial P25, which had an efficiency of 45 %. These findings provide valuable insights into the influence of the synthesis parameters on the development of high-performance TiO₂ photocatalysts for effective environmental remediation.