基于准隔离纳米结构的快速响应钯电阻式氢传感器研究

A critical parameter for hydrogen safety sensors is the response speed, which must be fast enough (< 1s at 4 vol% H2) so that people can have enough time for evacuation. Palladium (Pd) resistive hydrogen sensors based on anodic aluminum oxide (AAO) nanostructures have significant advantages over other hydrogen sensors because of their simple (low cost) and robust structures. However, the response of Pd thin film hydrogen sensors is very slow (1-25 min). Using nanoporous AAO as substrates, Pd resistive hydrogen sensors showed much faster response (～70s) than those on smooth substrates (～1500s) and their sensitivity at low concentrations were also improved. It should be noted that among the Pd resistive hydrogen sensors, Pd mesowires showed the fastest response (～80 ms) and very high sensitivity due to a new sensing mechanism, "break junction". In this project, the response kinetics of Pd to hydrogen is studied and the robust, low-cost, and fast response Pd resistive hydrogen sensors are developed based on quasi-isolated Pd nano-islands obtained through modification of AAO nanostructure. The specific project objectives are listed as follows: 1) Theoretical analysis and experimental studies of response kinetics of Pd to hydrogen; 2) Improvement of the response speed of the AAO-based Pd film hydrogen sensors through AAO nanostructure modification (<1s at 4 vol% H2); 3) Studies of sensors with respect to other important parameters, including sensitivity, range and accuracy, selectivity, recovery time, drift, reliability, and temperature effect.

氢传感器的响应速率应小于1秒（H2浓度小于4％）是保证有足够时间疏散人群的关键。采用纳米孔AAO为衬底的Pd薄膜电阻式氢传感器不仅响应速率（～70s）比平整衬底的Pd薄膜电阻式传感器响应速率（～1500s）快很多，而且在低浓度下的灵敏度也显著提高。基于"裂结"敏感机理的介观纳米线结构Pd电阻式氢传感器不仅具有最短的响应时间（80ms），又有很高的灵敏度。本项目研究基于准隔离纳米结构的Pd金属电阻式传感器的响应动力学，在纳米结构的AAO上以准隔离的纳米颗粒为敏感层，制备结构坚固，成本低廉，响应速率快的Pd电阻式氢传感器。具体研究内容包括：1）Pd对氢的响应动力学研究；2）通过使用改进的AAO纳米结构模板制备响应速率小于1秒（H2浓度小于4％）的Pd电阻式氢传感器；3）研究包括灵敏度，检测范围，准确性和选择性等在内的其它相关重要参数指标。

研究出高响应速率的氢传感器，响应速率应小于1秒（H2浓度小于4％），对氢气泄漏引起的危险预警提供了足够疏散人群的时间。采用了AAO纳米结构衬底，制备的Pd薄膜电阻式氢传感器响应速率（～70s）比平整衬底的Pd薄膜电阻式传感器响应速率（～1500s）快很多，在低浓度氢气氛围下的灵敏度也显著提高。提出了基于“裂结”的敏感机理，解释介观纳米线结构Pd电阻式氢传感器具有快响应时间和很高的灵敏度的物理机理。本项目研究了基于准隔离纳米结构的Pd金属电阻式传感器的响应动力学，在纳米结构的AAO上以准隔离的纳米颗粒为敏感层，制备出结构坚固，成本低廉和响应速率快的Pd电阻式氢传感器。研究内容包括：1）Pd对氢的响应动力学研究；2）通过使用改进的AAO纳米结构模板制备响应在低浓度条件下速率小于14秒（H2浓度小于1.4％）的Pd电阻式氢传感器，该结果接近申请书中较高浓度氢浓度响应速率应小于1秒（H2浓度小于4％）；3）研究包括灵敏度，检测范围，准确性和选择性等在内的其它相关重要参数指标。