| Membrane separation technology is one of the most important means in modern separation science.Among them,the use of new two-dimensional materials to construct functional films with nano-and sub-nano-sized membrane pores,due to their special transmission and screening behaviors for molecules and ions in solution,are used in seawater desalination,proton conduction,energy storage and other fields It has shown great application potential and has become a frontier topic in the field of membrane separation and nanotechnology.Among them,the realization of research related to the precise control of ion transport by cell membranes through gated potentials has aroused great interest from researchers,but it is difficult to achieve precise control of the surface potential of regular nanochannels in experimental techniques,so this aspect Most research focuses on theoretical calculation and simulation.In this study,ultrathin titanium carbide nanosheets were prepared,and a layered separation film of titanium carbide with regular nanochannels was constructed.On this basis,first,the transport behavior of ions of different sizes and valence states in the titanium carbide nanochannel was studied,and the effect of ion intercalation on the layered structure was discussed.Subsequently,by constructing an electrochemical three-electrode system,the surface potential of the titanium carbide nanochannel was accurately controlled.Based on this,experiments of different ion transmembrane transport were carried out to investigate the effect of the channel surface potential on ion movement behavior.In order to further explore the effects and causes of surface charge on ion transport behavior,we built an E-QCMD test platform based on a dissipative quartz crystal microbalance and an electrochemical workstation,and explored the interaction between ions and titanium carbide nanochannels with different surface charge densities and Influence Mechanism.The main results are as follows:(1)Single-layer titanium carbide nanosheets were prepared by "Minimally Intensive Layer Delamination" selective etching method.It is verified that the titanium carbide nanosheets have complete morphology,large lateral size and high uniformity.In addition,it is also confirmed that the titanium carbide nanochannels have good mechanical strength and flexibility.The nanosheets are evenly stacked and the interlayer structure is complete.(2)Under the condition that no external voltage is applied to the surface of the titanium carbide nanochannel,an ion permeation experiment was conducted to confirm that the ion permeability is related to its valence state and concentration.XRD analysis also confirmed the structural characteristics of the interlayer structure of the titanium carbide film in different solutions.After immersing the original dry film in pure water or salt solution,the interlayer spacing will change,but the interlayer spacing is in the order of Amy.Less than the diameter of most hydrated ions.(3)Build a three-electrode system.The results show that: a)The ion transmission rate changes significantly at different voltage values.The positive voltage can effectively accelerate the ion penetration.;b)According to the EQCM-D technology,the dissipation and frequency of the titanium carbide nanochannels when the voltage is applied are tested,and the changes in the structure of the titanium carbide film are monitored in real time,and it is found that a higher surface potential will attract the solution The middle counter ion enters the interlayer,increasing the repulsion of the adjacent nanosheets,thereby increasing the total interlayer spacing;c)Because the Stern layer in the electric double layer has different surface potential polarities,the Helmholtz layer and the outer layer The Helmholtz layer exists;d)Although the radius is larger Rb+ is easy to dehydrate into the inner Helmholtz layer under the action of static electricity,but due to its large steric hindrance effect. |
PDF Full Text Request