Enhanced photocatalytic activities of the heterostructured upconversion photocatalysts with cotton mediated on TiO2/ZnWO4:Yb3+,Tm3+

Abstract

To improve the photocatalytic efficiency and make full use of solar energy, ZnWO₄:Yb³⁺,Tm³⁺ (ZYT) was introduced as the upconversion luminescence agent on TiO₂ with a cotton template, and novel upconversion photocatalysts of TiO₂/ZnWO₄:Yb³⁺,Tm³⁺ (TZYT-C) were synthesized and optimized with 5%–30% of ZYT. The heterostructure between ZYT and TiO₂ was formed in the TZYT-C composites with the presence of tube-like morphologies due to the addition of the cotton template. UV (364 nm) and blue (484 nm) light was emitted from ZYT upon 980 nm NIR irradiation. The BET specific surface areas of all the TZYT-C composites increased from 37 m² g⁻¹ (TiO₂-C) to the maximum value of 75 m² g⁻¹ on 5%TZYT-C. The photocatalytic activities of the TZYT-C composites were tested using the degradation process of methyl orange (MO). 5%TZYT-C showed the highest degradation efficiency, with a value of 55.6% under sun-like irradiation for 210 min. The same performance was observed on 5%TZYT-C under NIR (λ ≥ 780 nm) irradiation, with a maximum removal rate of 9.02%, since 5%TZYT-C showed the most efficient electron–hole (e⁻/h⁺) pair separation, compared to ZYT and other TZYT-C composites.