University Rovira i Virgili, Department of Electronic, Electrical & Automatic Control Engineering (DEEEA), Tarragona, Spain.
Phys Chem Chem Phys. 2010 Mar 20;12(11):2639-47. doi: 10.1039/b921665k. Epub 2010 Jan 27.
DRIFTS, TGA and resistance measurements have been used to study the mechanism of water and hydrogen interaction accompanied by a resistance change (sensor signal) of blank and Pd doped SnO(2). It was found that a highly hydroxylated surface of blank SnO(2) reacts with gases through bridging hydroxyl groups, whereas the Pd doped materials interact with hydrogen and water through bridging oxygen. In the case of blank SnO(2) the sensor signal maximum towards H(2) in dry air (R(0)/R(g)) is observed at approximately 345 degrees C, and towards water, at approximately 180 degrees C, which results in high selectivity to hydrogen in the presence of water vapors (minor humidity effect). In contrast, on doping with Pd the response to hydrogen in dry air and to water occurred in the same temperature region (ca. 140 degrees C) leading to low selectivity with a high effect of humidity. An increase in water concentration in the gas phase changes the hydrogen interaction mechanism of Pd doped materials, while that of blank SnO(2) is unchanged. The interaction of hydrogen with the catalyst doped SnO(2) occurs predominantly through hydroxyl groups when the volumetric concentration of water in the gas phase is higher than that of H(2) by a factor of 1000.
DRIFTS、TGA 和电阻测量已被用于研究伴随电阻变化（传感器信号）的水和氢相互作用的机制，研究对象为空白和 Pd 掺杂 SnO(2)。研究发现，空白 SnO(2)的高度羟基化表面通过桥连羟基与气体反应，而 Pd 掺杂材料则通过桥连氧与氢和水相互作用。在空白 SnO(2)的情况下，在干燥空气中（R(0)/R(g)）对 H(2)的传感器信号最大值出现在大约 345 摄氏度，而对水的传感器信号最大值出现在大约 180 摄氏度，这导致在水蒸气存在下对氢具有高选择性（湿度影响较小）。相比之下，在掺杂 Pd 的情况下，在干燥空气中对氢的响应和对水的响应发生在相同的温度区域（约 140 摄氏度），导致选择性低且湿度影响大。气相中含水量的增加改变了 Pd 掺杂材料的氢相互作用机制，而空白 SnO(2)的氢相互作用机制则保持不变。当气相中氢的体积浓度比水高 1000 倍时，氢与催化剂掺杂 SnO(2)的相互作用主要通过羟基发生。
