Akademik Veri Yönetim Sistemi
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING, cilt.13, ss.1-24, 2025 (SCI-Expanded)
TiO2/WO3 nanocomposites with varying WO3 loadings were synthesized via a sol–gel method under acidic conditions (pH 1) and comprehensively evaluated for the selective photocatalytic oxidation of 3-methylpyridine and 3-pyridinemethanol in aqueous solution. Structural and surface analyses (XRD, BET, SEM-EDX, XPS, DRS, PL, and photocurrent measurements) confirmed the successful formation of TiO2/WO3 heterojunctions, which facilitated efficient charge separation and suppressed recombination. Compared with pristine TiO2 and WO3, the composites exhibited superior photocatalytic activity and selectivity toward valuable carbonyl compounds, namely 3-pyridinemethanal and vitamin B₃. While pristine WO3 displayed negligible photocatalytic activity and poor selectivity, commercial anatase TiO2 showed low activity and selectivity for 3-methylpyridine oxidation, but moderate performance for 3-pyridinemethanol oxidation. Among the series, TiO2-0.7WO3-300 showed the highest performance, affording a total 3-pyridinemethanal and vitamin B₃ yield of 40.2 % under UVA irradiation at neutral pH and up to 50 % vitamin B₃ yield under acidic conditions (pH 3). Radical scavenging experiments demonstrated that superoxide radicals were the dominant species for selective oxidation. Additional adsorption studies revealed that substrate–catalyst interactions play a critical role in influencing activity, while pH-dependent experiments indicated that the reaction medium strongly affects both the oxidation pathway and product distribution. Reusability and stability tests confirmed that the photocatalysts retained their efficiency over multiple cycles. Despite enhanced activity under UVA and UV–Vis light, the composites were inactive under visible light alone for 3-pyridinemethanol oxidation. These findings highlight TiO2/WO3 nanocomposites as robust and environmentally friendly photocatalysts for the selective synthesis of industrially relevant chemicals.