Large-scale fabrication of upconversion/quantum dots photocatalyst film by a facile spin-coating method

Facile and large-scale preparation of upconversion photocatalyst films is promising for the degradation of volatile organic compounds (VOCs), major component of the landfill gas stench. Herein, a spin-assisted layer-by-layer coating method is explored to fabricate the upconversion photocatalyst film of polyethylene terephthalate (PET)/Tm/Yb-doped NaYF4 (TYN)/P25/(CdSe/CdS) QDs (PET/TYN/P25/QDs). The near-infrared light energy passes through the top QDs and P25 layers to excite TYN, and the strong upconversion emissions of UV (290, 346, and 362 nm) and visible (452 and 476 nm) light are produced and absorbed by P25/QDs for photocatalysis. In the photocatalytic degradation of gaseous toluene, the removal efficiency over the PET/TYN/P25/QDs film reaches 83% after 1 h of simulated sunlight irradiation, which is much higher than that (40%) of the PET/TYN/P25 film. This better photocatalytic activity is ascribed to the large absorption edge of the CdSe/CdS QDs and the efficient electron-hole pair separation in the QDs-P25 heterostructure.