Palladium (Pd) has been drawing increasing attention as a hydrogen (H2) detecting material due to its highly selective sensitivity to H2. However, at H2 concentrations above 2%, Pd undergoes inevitable phase transition, causing undesirable electrical and mechanical alterations. In particular, non-linear gas response (ΔR/R0) that accompanies phase transition has been a great bottleneck to detect H2 in high concentrations, which is especially important as there is a risk of explosion over 4% H2. Here, we propose a phase-transition-inhibited Pd nanowire H2 sensor that can detect up to 4% H2 with high linearity and high sensitivity. Based on the calculation of the change in free energy, we designed Pd nanowires that are highly adhered to the substrate to withstand the stress that leads to phase transition. We theoretically optimized the Pd nanowire dimensions using a finite element method simulation and then experimentally fabricated the proposed sensor by exploiting a developed nanofabrication method. The proposed sensor exhibited high sensing linearity (98.9%) module that can detect H2 with high linearity, notifying real-time H2 leakage through remote communication. Overall, our work suggests a nano-structuring strategy for detecting H2 with phase-transition-inhibited pure-Pd H2 sensor with rigorous scientific exploration.

* Paper Title: Wireless and Linear Hydrogen Detection up to 4% with High Sensitivity through Phase-Transition-Inhibited Pd Nanowires

- https://pubs.acs.org/doi/full/10.1021/acsnano.2c01783

* Authors: Min-Seung Jo, Ki-Hoon Kim, Kwang-Wook Choi, Jae-Shin Lee, Jae-Young Yoo, Sung-Ho Kim, Heejeong Jin, Min-Ho Seo* and Jun-Bo Yoon*