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