Benedict Samatha, Lumdee Chatdanai, Dmitriev Alexandre, Anand Srinivasan, Bhat Navakanta
Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore, India.
Nanotechnology. 2018 Jun 22;29(25):255502. doi: 10.1088/1361-6528/aaba88. Epub 2018 Mar 29.
In this work we report on plasma oxidation of palladium (Pd) to form reliable palladium/palladium oxide (Pd/PdO ) core-shell sensor for ppb level HS detection and its performance improvement through nanostructuring using hole-mask colloidal lithography (HCL). The plasma oxidation parameters and the sensor operating conditions are optimized to arrive at a sensor device with high sensitivity and repeatable response for HS. The plasma oxidized palladium/palladium oxide sensor shows a response of 43.1% at 3 ppm HS at the optimum operating temperature of 200 °C with response and recovery times of 24 s and 155 s, respectively. The limit of detection (LoD) of the plasma oxidised beam is 10 ppb. We further integrate HCL, a bottom-up and cost-effective process, to create nanodiscs of fixed diameter of 100 nm and varying heights (10, 15 and 20 nm) on 10 nm thin Pd beam which is subsequently plasma oxidized to improve the HS sensing characteristics. The nanostructured Pd/PdO sensor with nanodiscs of 100 nm diameter and 10 nm height shows an enhancement in sensing performance by 11.8% at same operating temperature and gas concentration. This nanostructured sensor also shows faster response and recovery times (15 s and 100 s, respectively) compared to the unstructured Pd/PdO counterpart together with an experimental LoD of 10 ppb and the estimated limit going all the way down to 2 ppb. Material characterization of the fabricated Pd/PdO sensors is done using UV-vis spectroscopy and x-ray photoemission spectroscopy.
在本工作中，我们报道了钯（Pd）的等离子体氧化过程，以形成用于检测十亿分之一（ppb）级硫化氢（HS）的可靠的钯/钯氧化物（Pd/PdO）核壳传感器，并通过使用孔掩膜胶体光刻技术（HCL）进行纳米结构化来提高其性能。优化等离子体氧化参数和传感器操作条件，以获得对HS具有高灵敏度和可重复响应的传感器器件。等离子体氧化的钯/钯氧化物传感器在200℃的最佳操作温度下，对3ppm的HS响应为43.1%，响应时间和恢复时间分别为24秒和155秒。等离子体氧化光束的检测限（LoD）为10ppb。我们进一步集成了HCL（一种自下而上且具有成本效益的工艺），在10nm厚的钯光束上创建固定直径为100nm且高度可变（10nm、15nm和20nm）的纳米盘，随后对其进行等离子体氧化以改善HS传感特性。直径为100nm且高度为10nm的纳米盘的纳米结构化Pd/PdO传感器在相同操作温度和气体浓度下，传感性能提高了11.8%。与非结构化的Pd/PdO对应物相比，这种纳米结构化传感器还显示出更快的响应和恢复时间（分别为15秒和100秒），实验检测限为10ppb，估计检测限低至2ppb。使用紫外可见光谱和X射线光电子能谱对制备的Pd/PdO传感器进行材料表征。
