Abstract The sensing reaction mechanism of ZnO toward H2 was studied, and the effect of humidity and Pt decoration on the sensor performance was also investigated. Sputter-deposited ZnO thin films exhibit a distinct sensing response to H2 at temperatures above 150°C. An inverse V-shape response feature may develop upon the H2 exposure depending on the H2 concentration and the working temperature. The characteristic response feature results from a series of surface processes occurring on the ZnO surface, including ZnO reduction, Zn nanocluster growth, O2 adsorption on Zn nanoclusters and reoxidation of the nanoclusters. The sensor response to H2 is greatly deteriorated in humid ambient. However, the sensor shows a response enhancement toward humid H2 gas mixtures if the sensor surface is prepared to be initially free from H2O adspecies. This suggests that coexistence of hydrogen and water adspecies on the ZnO surface improves the sensor response to H2. When the ZnO thin film is decorated with Pt nanoparticles, the sensor performance is greatly improved both in dry and in humid environments. The improvement is proposed to result from hydrogen spillover from Pt nanoparticles to the ZnO support, which enhances the reaction rate of ZnO reduction by hydrogen adatoms.

中文翻译：

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ZnO 在低于 300°C 的温度下对 H2 的气敏行为及其对湿度和 Pt 修饰的依赖性

摘要 研究了ZnO对H2的传感反应机理，并研究了湿度和Pt修饰对传感器性能的影响。溅射沉积的 ZnO 薄膜在高于 150°C 的温度下对 H2 表现出明显的传感响应。取决于 H2 浓度和工作温度，H2 暴露可能会产生反 V 形响应特征。特征响应是由发生在 ZnO 表面上的一系列表面过程引起的，包括 ZnO 还原、Zn 纳米团簇的生长、Zn 纳米团簇上的 O2 吸附和纳米团簇的再氧化。在潮湿环境中，传感器对 H2 的响应会大大恶化。然而，如果传感器表面准备好最初不含 H2O 物质，则传感器对潮湿的 H2 气体混合物的响应增强。这表明 ZnO 表面上的氢和水共存改善了传感器对 H2 的响应。当用 Pt 纳米粒子装饰 ZnO 薄膜时，传感器在干燥和潮湿环境中的性能都得到了极大的提高。提出这种改进是由于氢从 Pt 纳米粒子溢出到 ZnO 载体上，从而提高了氢吸附原子对 ZnO 还原的反应速率。