基于“点接触”纳米间隙阵列结构制备高性能钯氢电学传感器

Pd-based nanogap is one of important electrochemical H2 sensors. The working principle is based on the volume expansion of Pd after H2 exposure, which allows the nanogaps to be closed, leading to a substantial inflow of electrical current. However, the presence of substrate plays a remarkable negative effect on the sensing performance, due to its restraint to the expansion and shrinkage of the Pd structure. In this project, one novel type of Pd nanogap, which has only point contact with the substrate, is designed and fabricated. The “point contact” nanogap arrays can be fabricated trough two strategies. One is to etch the substrate, and the other one is to assembly nanoparticles on a flat surface. In this kind of nanostructures, areas that don’t contact with the substrate can swell and shrink freely in H2 environment, while areas contact with the substrate offer the structure sufficient mechanical stability. Therefore, the fabrication of the so-called “point contact” Pd nanogaps is an effective route to obtain stable and sensitive electrochemical H2 sensors. Furthermore, compared with nanostructures contacting directly with the substrate, the “point contact” nanostructures has a relatively larger surface area, which would improve the response rate to H2. Additionally, the effects of structural parameters on the sensing performance are also investigated. This project offers a new idea to fabricate high performance electrochemical H2 sensors, which is of great scientific significance and application prospects.

钯氢电学传感器是一类重要的氢气传感器，其原理是金属钯吸氢后体积膨胀，使纳米间隙闭合形成导电通路来进行检测。但是基底的存在限制了钯的形变过程，严重影响了传感器的性能。本项目拟设计制备一类与基底存在“点接触”的金属钯纳米间隙阵列结构，利用基底刻蚀和球形粒子组装两种思路，拟分别制备 “悬浮”钯纳米三角形阵列结构以及二维有序中空钯壳层粒子阵列结构。在“点接触”结构中，未与基底接触的部分可以在氢气气氛中自由膨胀收缩，而与基底接触的部分赋予了传感器足够的机械强度，因此可以在消除基底效应的同时又保证传感器足够的稳定性。同时，相对于完全依附于基底的结构，“点接触”结构具有更高的比表面积，有利于增加传感器的响应速率。在此基础之上，本项目拟全面深入地研究各类结构参数对于传感器性能的影响。本项目的实施，为高性能钯氢电学传感器的设计与制备提供了新的思路和方法，具有重要的科学意义和应用前景。

本项目主要致力于具有特殊形貌的金属微结构的构筑，（包括球形纳米粒子、金属壳层粒子及纳米铃铛粒子等），通过改变合成条件实现对这些粒子的微观形貌的调控及优化；随后，以所制备的金属粒子为构筑基元，通过界面自组装以及溶剂诱导自组装等方式，实现对于金属纳米粒子的可控组装；并在此基础上，利用具有粘附能力的高分子作为高分子插层，引入金属结构与基底之间，从而提高微纳结构与基底之间的黏附力。最后我们研究了各种结构参数对于氢气传感性能的影响。主要包括壳层粒子尺寸、表面粗糙度、壳层厚度对于样品氢气传感性能的影响。我们发现减小壳层厚度，调控合适的粒子尺寸对于增强氢气传感性能具有重要意义。实验中，我们能达到的氢气最低检测限为75 ppm。与此同时，我们发现改变粒子尺寸可以抑制α-β相变所带来的信号突变，并使氢气检测在更宽的范围内更易控制。