Yurchenko Olena, Benkendorf Mike, Diehle Patrick, Schmitt Katrin, Wöllenstein Jürgen
Fraunhofer Institute for Physical Measurement Techniques (IPM), 79110 Freiburg, Germany.
Fraunhofer Institute for Microstructure of Materials and Systems (IMWS), 06120 Halle, Germany.
Nanomaterials (Basel). 2024 Oct 10;14(20):1619. doi: 10.3390/nano14201619.
To meet today's requirements, new active catalysts with reduced noble metal content are needed for hydrogen sensing. A palladium-functionalized nanostructured NiCoO catalyst with a total Pd content of 4.2 wt% was synthesized by coprecipitation to obtain catalysts with an advantageous sheet-like morphology and surface defects. Due to the synthesis method and the reducible nature of NiCoO enabling strong metal-metal oxide interactions, the palladium was highly distributed over the metal oxide surface, as determined using scanning transmission electron microscopy and energy-dispersive X-ray investigations. The catalyst tested in planar pellistor sensors showed high sensitivity to hydrogen in the concentration range below the lower flammability limit (LFL). At 400 °C and in dry air, a sensor response of 109 mV/10,000 ppm hydrogen (25% of LFL) was achieved. The sensor signal was 4.6-times higher than the signal of pristine NiCoO (24.6 mV/10,000 ppm). Under humid conditions, the sensor responses were reduced by ~10% for Pd-functionalized NiCoO and by ~27% for NiCoO. The different cross-sensitivities of both catalysts to water are attributed to different activation mechanisms of hydrogen. The combination of high sensor sensitivity to hydrogen and high signal stability over time, as well as low cross-sensitivity to humidity, make the catalyst promising for further development steps.
为满足当今的需求，氢气传感需要新型的、贵金属含量降低的活性催化剂。通过共沉淀法合成了一种总钯含量为4.2 wt%的钯功能化纳米结构NiCoO催化剂，以获得具有有利片状形态和表面缺陷的催化剂。由于合成方法以及NiCoO的可还原性质能够实现强的金属-金属氧化物相互作用，通过扫描透射电子显微镜和能量色散X射线研究确定，钯高度分布在金属氧化物表面。在平面pellistor传感器中测试的该催化剂在低于可燃下限（LFL）的浓度范围内对氢气表现出高灵敏度。在400°C和干燥空气中，对于10,000 ppm氢气（LFL的25%）实现了109 mV的传感器响应。该传感器信号比原始NiCoO的信号（24.6 mV/10,000 ppm）高4.6倍。在潮湿条件下，钯功能化NiCoO的传感器响应降低了约10%，NiCoO的传感器响应降低了约27%。两种催化剂对水的不同交叉敏感性归因于氢气的不同活化机制。对氢气的高传感器灵敏度、随时间的高信号稳定性以及对湿度的低交叉敏感性的结合，使得该催化剂在进一步的开发步骤中具有前景。
