Conventional wastewater treatment technologies are often ineffective in eliminating persistent micropollutants, such as neonicotinoid pesticides, which pose significant risks to ecosystems and human health. To address this challenge, silicon-modified black titanium dioxide (Si-b-TiO 2 ) photocatalysts were synthesised via a sol–gel route followed by chemical reduction, targeting sustainable environmental remediation under full-spectrum solar irradiation. Controlled Si incorporation (1–15 wt%) tuned the structural, optical, and electronic properties of black TiO 2 , as confirmed by XRD, TEM, and XPS and FT-IR analyses. Silicon modification suppressed electron–hole recombination and enhanced visible-light absorption, accompanied by increased generation of reactive oxygen species, as evidenced by hydroxyl radical ( HO ∙ ) probing using terephthalic acid fluorescence. The optimised Si1-b-TiO 2 photocatalyst achieved an imidacloprid degradation efficiency of approximately 70% within 180 min under full-spectrum irradiation, compared to ∼34% for pristine black TiO 2 , corresponding to an apparent rate constant of k = 6.84 ⋅ 10 −3 min −1 . In addition, the catalyst retained more than 90% of its initial activity after five consecutive degradation cycles, demonstrating good operational stability. At higher Si loadings (≥5 wt%), performance decreased due to pore blockage and recombination, underlining the importance of controlled doping. This work demonstrates that Si-modified black TiO 2 provides a cost-effective and scalable material platform for solar-driven water purification, contributing to the development of sustainable technologies for mitigating micropollutants. • Si-modified black TiO 2 synthesised via sol-gel and NaBH 4 reduction methods. • 1% Si-modified black TiO 2 showed 70% imidacloprid degradation in 3 h under full-spectrum light. • Si incorporation introduced mid-gap states and enhanced visible light absorption. • PL analysis showed reduced charge recombination with increasing Si content. • Surface Si incorporation improved charge separation and photocatalytic efficiency.
Vijayan et al. (Wed,) studied this question.