A first blue fluorescence composite film based on graphitic carbon nitride nanosheets/polyoxometalate for application in reversible electroluminescence switching

Abstract

In this work, for the first time we constructed a multifunctional blue-fluorescence composite film based on photoluminescent protonated graphitic carbon nitride nanosheets (g-C₃N₄NS) and reversible electrochromic silicomolybdotungstate K₈(SiMoW₁₀O₃₉)·13H₂O (SiMoW) by the layer-by-layer (LBL) assembly method. Firstly, SiMoW and g-C₃N₄NS were synthesized, and their structure, morphology and properties were verified by FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy), CV (Cyclic Voltammetry) and fluorescence spectroscopy. Then, the composite films containing SiMoW and g-C₃N₄NS were assembled, and their assembly process, morphology, composition and properties were characterized by means of UV-vis absorption spectroscopy, CV, amperometry and fluorescence spectroscopy, XPS (X-ray Photoelectron Spectroscopy) and AFM (Atomic Force Microscopy). Finally, the reversible electrofluorochromic properties of the composite film [(PEI/SiMoW)₂₅/(g-C₃N₄NS/SiMoW)₃/(PEI/SiMoW)₂] (PEI: poly(ethyleneimine)) were investigated by in situ spectroelectrochemical systems based on the fluorescence resonance energy transfer mechanism. The results show good blue-fluorescence switching performance, stability and reversibility of this composite film. This is the first demonstration of POM control of blue luminescence switching.