Research On The Construction Of Electrochemical Sensing Interface Based On Titanium Carbide/noble Metal Nanocomposite Materials

Two-dimensional（2D）transition metal carbides,nitrides or carbonitrides（MXenes）have attracted much attention in many fields such as sensing and energy because of their good electrical conductivity,large specific surface area and easy-adjustable surface properties.As one of the most mature MXenes,titanium carbide（Ti₃C₂T_X）has become a research hotspot of 2D materials.Noble metal nanoparticles（NPs）have great application potential in the field of electrochemical sensors（ECS）due to their special physical and chemical properties.The composite material of Ti₃C₂T_X and NPs not only increases the specific surface area of the material,but also prevents the stacking of Ti₃C₂T_X sheets,which makes the composite material have faster mass transfer rate and electron conduction capacity.In this thesis,using the electrochemical detection method,NPs/Ti₃C₂T_X nanocomposites are prepared for the electrochemical sensing interface,and the application of the nanocomposites in the detection of nitrite and thrombin is studied.A novel electrochemical sensing interface is constructed based on Au NPs/Ti₃C₂T_X nanocomposites and applied to the detection of nitrite.During the stripping process,hydrofluoric acid（HF）is used for functionalization of Ti₃C₂T_X,generating functional groups such as hydroxyl groups and carboxyl groups on the surface,which makes the gold nanoparticles（Au NPs）uniformly supported on the surface of Ti₃C₂T_X sheets.That can prevent the 2D sheets of Ti₃C₂T_X from stacking and influence the electron transfer.The experimental results show that the ECS based on the Au NPs/Ti₃C₂T_X sensing interface has a wide linear concentration range（1.0μM to 4581.1μM）and an ultra-low detection limit（0.14μM）when detecting nitrite ions.The ECS also has high sensitivity and strong anti-interference ability.Ag NPs/TiO₂ NR/Ti₃C₂T_X three-dimensional（3D）nanocomposites are synthesized by one-step hydrothermal method and applied to the construction of label-free thrombin ECS.The 3D structure of the composite provides a large active surface area that facilitates the attachment of silver nanoparticles（Ag NPs）.Under hydrothermal conditions,the Ti atoms on the 2D Ti₃C₂T_X sheets are oxidized to form titanium dioxide nanorods（TiO₂ NR）,and the TiO₂ NR grown on the sheet can prevent the stacking of the sheets and increase the gap between the layers.This can increase the mass transfer rate.At the same time,Ag NPs can be linked to thrombin aptamers via Ag-S bonds to construct a sensitive label-free electrochemical sensing interface for the determination of thrombin.The constructed ECS has good electrochemical performance,wide linear range（5 fM-500 nM）and low detection limit（2 fM,S/N=3）.The experimental results show that the ECS constructed by the Ag NPs/TiO₂NR/Ti₃C₂T_X nanocomposites can achieve rapid and sensitive detection of thrombin.