Impact of Pd nanoparticle loading method on SnO2 surface for natural gas detection in humid atmosphere
Impact of Pd nanoparticle loading method on SnO2 surface for natural gas detection in humid atmosphere
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DOI：
10.1007/s10853-021-06214-4
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发表时间：
2021-06-07
影响因子：
4.5
通讯作者：
Shimanoe, Kengo
中科院分区：
文献类型：
--
作者：
Liu, Chengcheng;Suematsu, Koichi;Shimanoe, Kengo
为了改善传感器在低工作温度和潮湿环境下对低浓度甲烷（CH 4）的响应，我们通过两种不同的Pd负载方法制备了Pd负载的SnO 2（Pd-SnO 2）纳米颗粒：（i）常规浸渍方法和（ii）使用聚（N-乙烯基-2-吡咯烷酮）（PVP）作为Pd受体颗粒保护剂的新负载方法。根据测量的电阻，Pd颗粒限制了SnO 2颗粒表面的羟基中毒。由于Pd被氧化成PdO，在PdO和SnO 2之间的界面处形成p-n结，并且这种界面使得电子耗尽层增大。因此，Pd进一步提高了SnO 2表面在潮湿空气中的抗羟基中毒性。此外，尽管基于纯SnO 2的传感器在200-400 ℃下对低浓度CH 4没有响应，但是基于负载Pd的SnO 2样品的两种传感器在潮湿气氛中对200 ppm CH 4表现出高传感器响应。通过新的负载方法获得的Pd-SnO 2在较低的工作温度范围（200-250摄氏度）内对较低浓度的CH 4表现出更高的响应。传感器响应的这种改善可能是由于较大的Pd纳米颗粒的催化活性。根据高分辨率透射电子显微镜-能量色散X射线光谱图像，新的负载方法成功地提供了Pd负载的SnO 2纳米粒子与Pd纳米粒子均匀分散在SnO 2粒子表面。结果表明，采用新的负载方法负载在SnO 2表面的Pd纳米粒子的平均粒径略大于浸渍法负载的Pd纳米粒子的平均粒径。随着Pd粒径的增大，可以认为更容易形成结晶PdO颗粒，从而提高了CH 4在潮湿条件下的燃烧活性。这些结果对于进一步降低CH 4传感器的能量消耗和提高其在潮湿环境中的传感器响应具有重要意义。
To improve the sensor response to low concentrations of methane (CH4) at low operating temperatures in humid atmospheres, we prepared Pd-loaded SnO2 (Pd-SnO2) nanoparticles via two different Pd-loading processes: (i) a general impregnation method and (ii) a new loading method using poly(N-vinyl-2-pyrrolidone) (PVP) as a protective agent for Pd receptor particles. According to the measured electric resistances, the Pd particles limited the hydroxyl-poisoning of the SnO2 particle surface. Because Pd is oxidized to PdO, a p-n junction is formed at the interface between PdO and SnO2, and such interface gives the enlargement of the electron depletion layer. Therefore, Pd further improved the resistance against hydroxyl poisoning of the SnO2 surface in humid air. In addition, although the sensor based on neat SnO2 did not respond to low-concentration CH4 at 200-400 degrees C, both the sensors based on the Pd-loaded SnO2 samples exhibited high sensor response to 200 ppm CH4 in a humid atmosphere. The Pd-SnO2 obtained by the new loading method exhibited a higher response to CH4 at lower concentrations in the lower operating temperature range (200-250 degrees C). This improvement in the sensor response is probably due to the catalytic activity of the larger Pd nanoparticles. According to high-resolution transmission electron microscopy-energy-dispersive X-ray spectroscopy images, the new loading method successfully provided Pd-loaded SnO2 nanoparticles with Pd nanoparticles dispersed uniformly on the SnO2 particle surface. The average particle size of Pd nanoparticles loaded on the surface of SnO2 by the new loading method was slightly larger than that of the Pd nanoparticles loaded by the impregnation method. As the Pd particle size increases, it is thought that crystalline PdO particles are formed more easily, thereby improving the combustion activity of CH4 under humid conditions. These results are of great significance for further decreasing the energy consumption of the CH4 sensor and increasing its sensor response in humid atmospheres.