Study On Mxene （Ti₃C₂T_x） Based Electrochemical Actuation Behavior

Electrochemical actuators are devices that convert electrical energy into mechanical energy through electrochemical processes,and they are widely used in soft robotics,artificial muscles,micro-pumps,sensors,and smart switches.The electrode materials that have been successfully applied to electrochemical actuators include:conductive polymers,carbon nanotubes,graphene,Mo S₂and graphdiyne,etc.The development of flexible,stable,large deformation and high mechanical strength electrode materials remains a major challenge in this field.MXenes,as an emerging family of two-dimensional materials,has been widely used in the field of electrochemical energy storage due to its flexibility,high energy density,excellent rate performance,high electronic conductivity and high mechanical strength.However,there are few related studies on MXenes in the field of electrochemical actuators.In this paper,the most widely studied Ti₃C₂T_xamong MXenes materials is the main research object,to explore the electrochemical actuation performance of electrode materials in different electrolytes,and to further improve the actuation performance through structural design.The research results are as follows:Firstly,we found that the appropriate extension of the Ti₃C₂T_xetching time could increase the spacing of Ti₃C₂T_xlayer and form the hole structure on the surface,which was beneficial to shorten the diffusion distance of ions and improve the diffusion efficiency of ions,and the electrochemical actuation performance of Ti₃C₂T_xwere significantly improved.In 1 M Mg SO₄,the capacity retention rate increased from10.9%to 23.7%,and the Ti₃C₂T_xcurvature obtained by etching for 3 days was 2.22times that of Ti₃C₂T_xobtained by etching for 1 day.After 10,000 cycles,the actuation performance retention rate increased from 50.6%to 78.9%.Then,we explored the actuation performance of Ti₃C₂T_xin neutral electrolyte and alkaline electrolyte,and found that the actuation performance of Ti₃C₂T_xwas related to the hydrative cationic radius,and the larger the hydrated cation,the higher the actuation performance.Subsequently,we tested the electrochemical actuation performance of Ti₃C₂T_xin 1M H₂SO₄electrolyte,and the results show that at 1 m Hz frequency,the curvature of Ti₃C₂T_xsingle electrode can reach 0.083 mm^-1and the strain value is 0.29%,and the performance is comparable to that of the graphene actuator.The actual operating environment of the actuator is usually open environment,so we developed a model of the actuator that can work in the air.Two symmetrical strip Ti₃C₂T_xelectrodes are separated by a PVA-H₂SO₄solid electrolyte.Due to the thicker device and not high electric conductivity of solid electrolyte,the actuator has low curvature and strain values of 0.038 mm^-1and 0.26%at 1 m Hz frequency,but this device has a more realistic application.After 10,000 cycles,the actuation performance remains 80.4%of the initial performance.The in-situ XRD results showed that the intercalation/deintercalation of protons in the Ti₃C₂T_xinterlayers leading to the change in the interlayer space of Ti₃C₂T_x,which has led to the driving behavior.Finally,sulphuric acid has a potential hazard to the human body,and it is not conducive to environmental protection,but the actuation performance of Ti₃C₂T_xin neutral electrolyte is not ideal,so we designed a synergistic Ti₃C₂T_x/PPy bilayer electrochemical actuator.Ti₃C₂T_x/PPy bilayer film was prepared by depositing PPy on the surface of Ti₃C₂T_xby a simple electrodeposition method.Raman spectroscopy results showed that the deposition of PPy on Ti₃C₂T_xsurface effectively prevented the oxidation of Ti₃C₂T_x.The Ti₃C₂T_xlayer effectively improves the electronic conductivity of Ti₃C₂T_x/PPy,and acts as a co-actuation and conductive additive for the current collection layer.Meanwhile,the Ti₃C₂T_xlayer effectively accelerates the redox reaction rate of the PPy layer and improves the actuation performance.In neutral Li Cl O₄electrolyte,the curvature change of the Ti₃C₂T_x/PPy bilayer film increased by57%compared with the pure PPy film at a scan rate of 5 m V/s.After 10,000 cycles,the actuation performance of the Ti₃C₂T_x/PPy bilayer can still be maintained to 69.2%of the initial performance.Reasonable electrode structure design provides more possibilities for the application of MXene material in neutral electrolytes,and provides a new idea for achieving higher actuation performance.To sum up,the relevant research work of this paper focuses on Ti₃C₂T_xbased electrochemical actuator,realizing the application of MXenes materials in the field of electrochemical actuator,exploring the electrochemical actuation performance of electrode material in different electrolytes,and structural design of Ti₃C₂T_xto further improve the performance of the actuator,and achieving good experimental results.It provides the theoretical and experimental basis for the application of MXenes materials in the field of electrochemical actuators.