Fabrication of TiO2-WO3 S-Scheme Heterojunction for High-Efficiency Visible-Light Photocatalysis

Driven by the progress of sustainable development, environmental remediation and water treatment have become increasingly important. Photocatalysis, capable of degrading pollutants through light (especially visible light) irradiation, has received widespread research attention. Titanium dioxide(TiO2) is a promising photocatalyst, yet its practical use is limited by low visible-light utilization and rapid photogenerated charge recombination. Herein, an S-scheme TiO2-WO3(Tungsten trioxide) heterojunction was successfully fabricated; the difference in Fermi levels induces a built-in electric field directed from TiO2 to WO3, which thus constructs the S-scheme heterojunction. The as-prepared heterojunction exhibits a markedly enhanced transient photocurrent density, with the carrier lifetime prolonged from 2.69 ns to 41.61 ns. Under visible-light irradiation, the heterojunction achieves a methylene blue (MB) removal efficiency of over 95% within 90 min, and its pseudo-first-order kinetic rate constant k reaches 0.032 min−1, which is approximately 16 times that of pure TiO2. Radical trapping experiments confirm that the dominant active species responsible for the catalytic process are photogenerated holes and the hydroxyl radicals derived therefrom.