Development of Nanofluidic Thermoelectric Devices Using Two-Dimensional Materials

我们在透射电子显微镜下固化了在悬浮的二维材料上制备纳米孔的核心技术。具体地说，我们展示了从亚纳米到5纳米的孔磨，显示了孔尺寸的可控性。提出了一种多次钻孔工艺，并对其进行了测试，显示出出色的空间分辨率。对于每一次钻孔，孔径可以控制在1纳米以内。通过在略有不同的位置重复这一过程，可以精确地雕刻出所需的孔形状。利用这种方法，我们得到了圆度较高的小于5纳米的孔洞。同时，我们建立了流经纳米孔芯片的离子电流测量的流动系统，热源的温度控制器和用于热电评估的购买的电流计。由纳米孔膜隔开的储油层内的温度可以精确控制。另一方面，建立了基于Poisson-Nernst-Planck方程和Navier-Stokes方程的理论模型来预测系统的热电性能。结果表明，当特征双电层厚度接近气孔半径时，功率密度达到最大。这将通过选择合适的溶液条件来指导我们的实验设计。

We have solidified the core technique for nanopore fabrication on suspended two-dimensional materials under transmission electron microscopy. Specifically, we demonstrated pore milling from sub-nanometer to 5 nanometers, showing the controllability of the pore dimension. A multiple drilling process is proposed and tested showing outstanding spacial resolution. For each drilling the pore size can be controlled within one nanometer. By repeating the process at slightly different locations, the desired pore shape can be precisely sculpted. Using this method, we have created sub-5 nanometer pores with high circularity. In the meanwhile, we have constructed the flow system for ionic current measurements through nanopore chips, temperature controllers for heat source and purchased current meters for thermoelectric evaluations. The temperature in the reservoirs separated by the nanopore membrane can be precisely controlled. On the other hand, a theoretical model based on the Poisson-Nernst-Planck and Navier-Stokes equations has been constructed to predict thermoelectric performance of our system. It is shown that the power density reaches the maximum as the characteristic electric double layer thickness becomes close to the pore radius. This will guide our experimental design by selecting suitable solution conditions.