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

•Dual-layered up-conversion films achieved multi-peaks emission spectrum.•Light absorption and emission behaviors from different film surfaces were clarified.•Fluorescence properties were adjusted conveniently by excitation light intensities.•The emission spectra were tuned to match the absorption spectra of photocatalysts.•Dual-layered UC films enhanced the photocatalytic degradation capability.