Dual-layered up-conversion films with tunable multi-peaks spectrum for efficient photocatalytic degradation

The incorporation of multiple up-conversion (UC) materials into dual-layered UC films presents a promising strategy for achieving multi-peaks spectrum. Here, we developed dual-layered UC films containing triplet-triplet annihilation up-conversion luminescence (TTA-UCL) chromophores and NaYF4:Yb3+,Tm3+ nanoparticles to enable multi-peaks emissions at 340-360 and 390 nm in the transmission manner and 340, 360 and 400-440 nm in the reflection manner under irradiations of green and NIR light. The light absorption and emission behaviors from different film surfaces were studied clearly. Besides, TiO2 and g-C3N4 with different absorption spectra were chosen to verify the availability of the dual-layered films to tune emission spectra. When both green and NIR light were used simultaneously, TiO2 and g-C3N4 can degrade tetracycline (TC) by 2.14 and 1.77 times more than the cases where single light was used alone. The photocatalytic abilities of TiO2 or g-C3N4 can be further improved by the selective increase in NIR or green light power density due to their different absorption spectra. The dual-layered films containing TTA-UCL chromophores and NaYF4:Yb3+,Tm3+ nanoparticles provide a candidate framework for UC systems with tunable short-wavelength spectra to expand their applications in the fields of photocatalysis.