Preparation And Application Of Ti₃C₂T_x Mxene-based Composites

MXene is a new family of two-dimensional(2D)transition metal carbides and nitrides.Among them,Ti₃C₂T_x has aroused much attention in various research fields due to its high conductivity,abundant surface functional groups and excellent photothermal properties.However,the related research is still in its infancy,especially in the energy storage and conversion systems and biomedical systems,which needs further exploration and investigation.In this dissertation,several MXene-based composites were prepared and their applications in lithium ion batteries,electrocatalysis,and bio-antibacterial were discussed and evaluated in detail.(1)The Si/Ti₃C₂T_x composite was constructed via layer-by-layer self-assembly method and used as the anode of lithium ion batteries.Due to the excellent electrical conductivity and mechanical property of Ti₃C₂T_x,the Si/Ti₃C₂T_x electrode exhibits better electrochemical performance compared with the pristine Si anode in lithium ion batteries.The batteries with composite anodes deliver a specific capacity of 1130 m Ah g^–1 after 200 cycles at 500 m A g^–1.The distinctive performance mainly benefits from the fact that Ti₃C₂T_x can effectively alleviate the huge volume expansion of Si anode upon cycling and prevent the active materials from detaching from the current collectors.Meanwhile,Ti₃C₂T_x can ensure the electric contact between Si nanoparticles and the electrode during repeated discharge/charge processes.This system could alleviate the issues of pulverization and poor conductivity of Si anode distinctively.(2)The Fe-Co prussian blue analogue precursor was obtained by in-situ growth on the Ti₃C₂T_x surface.After phosphorization,the Fe P-Co P/Ti₃C₂T_x composite was evaluated as an electrocatalyst for oxygen evolution reactions.Benefiting from the superior conductivity and hydrophilicity of Ti₃C₂T_x,the Fe P-Co P/Ti₃C₂T_x composite exhibits an overpotential of 290 m V(j=10 m A cm^–1)and a Tafel slope of 64 m V dec^–1,which are much lower than that of pristine Fe P-Co P.The smaller overpotential and Tafel slope indicate the higher catalytic activity and faster reaction kinetics.Ti₃C₂T_xcan remarkably enhance the efficiency of electron transportation and electrocatalytic performance.The double-layer capacitance test and electrochemical impedance spectroscopy demonstrate that the Fe P-Co P/Ti₃C₂T_x composite possesses a large electrochemical active area and low charge transfer resistance.The smaller size of Fe P-Co P/Ti₃C₂T_x cube can increase the contact area between the electrolyte and catalysts,thus facilitating the electrocatalysis process.This in-situ growth strategy could handle the problems of poor conductivity and limited active sites of prussian bule derivate electrocatalysis.(3)The photothermal-enhanced antibacterial agent Ag/Ti₃C₂T_x composite was synthesized through an in-situ reduction reaction by sodium citrate in the boiled solution.Ti₃C₂T_x can also be applied in biomedical research to solve the biotoxicity of high-dose Ag antibacterial nanoparticles due to its striking photothermal property and good biocompatibility.The results demonstrate that the growth of E.coli can be inhibited completely by 200?g m L^–1 Ag/Ti₃C₂T_x.More importantly,the antibacterial effect of Ag/Ti₃C₂T_x composite is significantly strengthened upon the near-infrared light exposure.A synergetic antibacterial mode of intrinsic bacterial activity from Ag nanoparticles and photothermal bactericidal effect from Ti₃C₂T_x are verified.The photothermal template-assisted strategy can reduce the effective dose of Ag nanoparticles and improve the antibacterial effect.In the established animal model,the Ag/Ti₃C₂T_x-embedded hydrogels were used as wound dressings.They exhibit remarkable antibacterial effect and wound-healing performance,which expands their possibility in practical applications.