Thapa Magar Ashwin, Ngo Tu Anh, Luong Hoang Mai, Phan Thi Thu Trinh, Trinh Minh Tuan, Zhao Yiping, Nguyen Tho Duc
Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA.
Department of Electrical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
Nanomaterials (Basel). 2025 Jul 16;15(14):1105. doi: 10.3390/nano15141105.
Palladium (Pd) and titanium (Ti) exhibit opposite dielectric responses upon hydrogenation, with stronger effects observed in the near-infrared (NIR) region. Leveraging this contrast, we investigated Ti/Pd bilayer thin films as a platform for NIR hydrogen sensing-particularly at telecommunication-relevant wavelengths, where such devices have remained largely unexplored. Ti/Pd bilayers coated with Teflon AF (TAF) and fabricated via sequential electron-beam and thermal evaporation were characterized using optical transmission measurements under repeated hydrogenation cycles. The Ti (5 nm)/Pd (x = 2.5 nm)/TAF (30 nm) architecture showed a 2.7-fold enhancement in the hydrogen-induced optical contrast at 1550 nm compared to Pd/TAF reference films, attributed to the hydrogen ion exchange between the Ti and Pd layers. The optimized structure, with a Pd thickness of x = 1.9 nm, exhibited hysteresis-free sensing behavior, a rapid response time (t90 < 0.35 s at 4% H2), and a detection limit below 10 ppm. It also demonstrated excellent selectivity with negligible cross-sensitivity to CO2, CH4, and CO, as well as high durability, showing less than 6% signal degradation over 135 hydrogenation cycles. These findings establish a scalable, room-temperature NIR hydrogen sensing platform with strong potential for deployment in automotive, environmental, and industrial applications.
钯（Pd）和钛（Ti）在氢化时表现出相反的介电响应，在近红外（NIR）区域观察到更强的效应。利用这种对比，我们研究了Ti/Pd双层薄膜作为近红外氢传感平台，特别是在与电信相关的波长下，此类器件在很大程度上仍未得到探索。通过顺序电子束和热蒸发制备的涂覆有特氟龙AF（TAF）的Ti/Pd双层薄膜，在重复氢化循环下使用光透射测量进行了表征。与Pd/TAF参考薄膜相比，Ti（5 nm）/Pd（x = 2.5 nm）/TAF（30 nm）结构在1550 nm处的氢诱导光学对比度提高了2.7倍，这归因于Ti和Pd层之间的氢离子交换。优化后的结构，Pd厚度为x = 1.9 nm，表现出无滞后的传感行为、快速响应时间（在4% H2下t90 < 0.35 s）和低于10 ppm的检测限。它还表现出优异的选择性，对CO2、CH4和CO的交叉敏感性可忽略不计，以及高耐久性，在135次氢化循环中信号降解小于6%。这些发现建立了一个可扩展的室温近红外氢传感平台，在汽车、环境和工业应用中具有很强的部署潜力。
