Preparation,study On Optical Properties And Application In Latent Fingerprint Detection Of Two-dimensional Layered Ti₃C₂T_x

MXene is a new type of two-dimensional transition metal carbide/nitride/carbonitride materials.The large specific surface area,rich and adjustable surface functional groups,hydrophilicity,excellent conductivity,mechanical properties and magnetic properties make it become a new favorite in the fields of electrochemical energy storage,catalysis,antibacterial and sensors,et al.Since the discovery of MXene,its related research has been developed rapidly,but the current exploration of the optical properties of MXene materials is still lacking,which greatly limits the application of MXene in optics and related fields.Therefore,this paper takes Ti₃C₂T_x in MXene materials as the research object,reveals the internal connection and law of the structure,optical performance and fingerprint display effect of its micron-scale materials and two-dimensional quantum dots,and achieves a simple and highly sensitive colorimetric latent fingerprint detection and colorimetric-fluorescence latent fingerprint detection.It breaks through the bottlenecks of the existing technology,such as low sensitivity and narrow application range,and opens up a new way for the diversified application of MXene materials.The main research contents are as follows:1.Two-dimensional layered Ti₃C₂T_x was successfully prepared by hydrofluoric acid etching.The narrow band gap structure makes the Ti₃C₂T_x have broad light absorption properties in the ultraviolet-visible-near infrared range,which is beneficial to colorimetric detection.The surface of Ti₃C₂T_x is rich in-OH,-O and-F,which is conducive to better adhesion effect between the materials and fingerprint residues through electrostatic,hydrogen bond and van der Waals interactions.As a latent fingerprint detection reagent,Ti₃C₂T_x has realized the detection of the tertiary structure characteristics of latent fingerprint.Compared with traditional commercial detection reagents that can only roughly detect the secondary structure of fingerprints,Ti₃C₂T_x has a higher detection sensitivity.In addition,the material can realize the detection of latent fingerprints on various non-porous and porous substrates,aging latent fingerprints and overlapping fingerprints,and it is universal in latent fingerprint detection.2.The two-dimensional quantum dots of Ti₃C₂T_x were successfully prepared by the method of hydrothermal synthesis using two-dimensional layered Ti₃C₂T_x as the raw material.The extension of the reaction time and the increase of the reaction temperature are beneficial to increase the fluorescence quantum yield of two-dimensional quantum dots.When the reaction time is 12 h and the reaction temperature is 150 °C,the fluorescence quantum yield of quantum dots is up to 24.8%,which is the highest value reported so far.The high fluorescence quantum yield may be related to the surface effect of quantum dots.In order to avoid the problem of fluorescence quenching caused by the solidification of Ti₃C₂T_x quantum dots and at the same time to reduce the cost of fingerprint detection reagents,Ti₃C₂T_x quantum dots were combined with starch to realize colorimetric-fluorescent latent fingerprint detection.The tertiary structure of the latent fingerprint is clearly visible.The detection results of the two modes are mutually verified,which improves the accuracy of the detection.The addition of the fluorescent mode avoids the problem of similar color in colorimetric latent fingerprint detection and improves the universality of fingerprint detection.