Bio-inspired Transpiration Ion Pump And Energy Conversion Devices Based On MXene Ti₃C₂T_x

With the development and progress of human society,environmental pollution and energy crises have become increasingly serious,so exploring the use of renewable energy has become one of the ways to deal with it.Nanofluidics,as a discipline to explore ionic transportation at the nanometer scale,initially emerged in the fields of biology and medicine.Nowadays,designing intelligent bionic nanofluidic systems by simulating various complex ionic transportation processes of living organisms,which not only has shown wide application prospect in biomedical field,but also in the field of energy conversion.The bionic ionic channels can be used to harvest all kinds of external energy to convert into electric energy because of its characteristics of fast transportation flux,selectivity,gating,pump and so on,which is of great significance for exploring the utilization of renewable energy and solving the problem of resource shortage.MXene,as a new kind of two-dimension nanomaterial,MXene Ti₃C₂T_x can be used as a cation selective channel because of the surface groups of preparation process.At the same time,due to the structure stability,good electrical conductivity and light absorption and thermal conversion,MXene Ti₃C₂T_x is expected to be applied to the preparation and application of biomimetic nanofluidic devices.In this article,firstly showing a review of the characteristics and applications of nanofluidic and the two-dimension nanomaterial MXene;then the MXene Ti₃C₂T_xwas prepared into a thin membrane and coated on cellulose acetate for the preparation and research of biomimetic and energy conversion devices.The main results are as follows:MXene Ti₃C₂T_xwas obtained by using etching agents of hydrochloric acid and lithium fluoride,and then the membrane with certain structural stability,flexibility and light absorption properties was prepared by vacuum filtration and used in the construction of ion pump devices.The results show that the ion pump based on MXene can regulate the transportation of cation to the infrared irradiated area under 0.1 M KCl solution and an infrared light intensity of～600 m W/cm²,and has fast response,good reversibility and stability.When the solution on both sides of the Ti₃C₂T_x membrane has a concentration gradient,the device can pump the ionic transportation under inverse concentration gradient of the maximum of 200-fold.In addition,the MXene-based ion pump can be further used as an energy conversion device,and the power generation performance of the device can be improved by adjusting the infrared light intensity and membrane thickness.Finally,the working mechanism of imitating plant’s transpiration of the ion pump is proposed and explored.The cellulose acetate filters coated with MXene Ti₃C₂T_x were prepared by the method of immersion-drying and used for the construction of energy conversion devices.The results show that the device can achieve the conversion of chemical energy to electric energy under infrared illumination.Then we explored performance of power generation of the device at the different heights of the cellulose acetate filters and different concentrations of KCl solution,which shows the voltage of the device can up to～0.15 V when the height of the filter is 1.0 cm and the concentration of KCl solution is 1 M,and the performance of power generation of the device can be improved by enhancing the infrared light intensity.Lastly,we explore the power generation of the device for 0.5 M Na Cl solution and under one solar light,which proving the potential application of it.