ZnO@SiO2 Nanocapsules: Efficient Fluorescence for Latent Fingerprint Detection

Abstract As advanced fingerprint powders, fluorescent materials generally provide high sensitivity and improved contrast on the pigments or patterned surface, with high resolution. In this study, ZnO nanoparticles are used as fluorescent materials and are homogeneously embedded into SiO 2 matrix to prepare ZnO@SiO 2 nanocapsules. Compared with conventional methods, ZnO@SiO 2 nanocapsules are fabricated using the transparent ethanol solution of ZnO NPs and n‐Octyltriethoxysilane without any surfactants. Interestingly, a large number of ZnO NPs can be homogeneously embedded in the silica matrix, reducing the aggregation‐induced quenching effect. The maximum emission of the ZnO@SiO 2 nanocapsules powder is located at 530 nm under 325 nm irradiation, and the photoluminescence intensity and the sensitivity of latent fingerprints development depend on the quantity of ZnO NPs in the composites. The prepared fluorescent ZnO@SiO 2 nanocapsules show outstanding property applied as effective fluorescent eikonogens for the high‐sensitivity visualization of latent fingerprints on different porous and non‐porous substrates. It has been demonstrated that ZnO@SiO 2 nanocapsules compounds combine the admirable adhesion of silica powders to fingerprint residues with the excellent photoluminescence properties of ZnO to form a promising light‐emitting material for fingerprint.