Synthesis Design of Electronegativity Dependent WO3 and WO3?0.33H2O Materials for a Better Understanding of TiO2/WO3 Composites’ Photocatalytic Activity

The design of a semiconductor or composite system—with applications in materials science—is complex because its morphology and structure depend on several parameters. These parameters are the precursor type, solvent, pH solution, synthesis approach, shaping agents. This study gives meaningful insight regarding such WO3 materials. By systematically alternating (sodium tungstate dihydrate—NWH, ammonium hydrate—AMT), subsequently agents (halide salts—NaX, KX, hydrohalic acids—HX; X = F?, Cl?, Br?, I?), we have obtained semiconductors by hydrothermal treatment, which systems can enhance commercial TiO2 photocatalytic activity. We investigated three sample series: WO3-NWH-NaX/WO3-NWH-KX and, subsequently, WO3-AMT-HX. presence W+5 centers was evidenced Raman X-ray photoelectron spectroscopy. W+6 species affected band gap values NaX KX series; higher percentage caused redshift, while, HX series, it led to blue shift. Increased electronegativity halide anions has an unfavorable effect composites’ photoactivity. In contrast, case acids, had positive impact.