A series of lanthanide-based nanopaper (Nd-nanopaper) was synthesized via a neodymium organic framework (Nd-MOFs)-grafted TEMPO-oxidized cellulose nanofibrils (tCNF) using a solvothermal reaction. Not using the traditional down-conversion visible emissions of anti-counterfeiting techniques, this Nd-nanopaper achieved down-conversion near-infrared (NIR) and up-conversion visible emissions. The down-conversion luminescent property of these Nd-nanopapers exhibited characteristic NIR luminescence (λ_Em = 1080 nm) of Nd³⁺ ions with 311 nm excitation, undergoing an “antenna” effect. In contrast, the up-conversion visible light emission (λ_Em =450 nm) of Nd-nanopaper was detected under 580 nm excitation. The mechanism of up-conversion fluorescence was ascribed to excited-state absorption and energy transfer up-conversion. Interestingly, Nd-nanopaper induced both up and down-conversions for visible and NIR emissions that were completely devoid of the interference from fluorescent brighteners and background fluorescence. These switchable up and down-conversion fluorescent Nd-nanopapers with visible and NIR dual emissions or dual channels could be applied in high level anti-counterfeiting applications.

通过溶剂热反应，通过钕有机骨架（Nd-MOFs）接枝的TEMPO-氧化纤维素纳米纤维（tCNF）合成了一系列基于镧系元素的纳米纸（Nd-nanopaper）。这款Nd纳米纸没有使用传统的防伪技术进行下转换可见光发射，而是实现了下转换近红外（NIR）和上转换可见光发射。这些的Nd-纳米纸的下转换发光性能显示出特性NIR致发光（λ _EM的Nd = 1080纳米）³⁺离子与311纳米激发，发生一个“天线”的效果。与此相反，上转换可见光发射（λ _EM在580 nm激发下检测到Nd-纳米纸== 450 nm）。上转换荧光的机理归因于激发态吸收和能量转移上转换。有趣的是，Nd-纳米纸引起可见光和NIR发射的上转换和下转换，这完全避免了荧光增白剂和背景荧光的干扰。这些具有可见光和近红外双发射或双通道的可切换上，下转换荧光Nd纳米颗粒可用于高级防伪应用。