https://doi.org/10.1016/j.jphotochem.2025.116773

https://sj.jst.go.jp/news/202601/n0109-02k.html

A WO₃-embedded hydrogel (WFG) obtained through freeze–cross-linking showed high water purification capacity even in the presence of salts. Under visible-light irradiation, WFG decolorized indigo carmine (INC) 1.5-fold increase in rate than suspended WO₃ and 3.7-fold increase in rate than a WO₃-coated glass plate. Coexisting salts (NaNO₃, NaCl, Na₂SO₄, NaH₂PO₄) altered the decolorization efficiency; NaNO₃ and Na₂SO₄ enhanced, whereas Cl⁻ and H₂PO₄⁻ suppressed the reaction, indicating that ionic strength and anion-species affect contact efficiency and charge transfer. WFG maintained >90 % of its initial IC-removal rate after five reuse cycles with minimal weight loss (< 3 %). These results clarify the structure–function relationship of gel-based photocatalysts and highlight their promise for practical visible-light water purification under variable ionic strengths.