Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST) , 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
ACS Nano. 2017 Sep 26;11(9):9276-9285. doi: 10.1021/acsnano.7b04529. Epub 2017 Aug 28.
The oxygen, O, in air interferes with the detection of H by palladium (Pd)-based H sensors, including Pd nanowires (NWs), depressing the sensitivity and retarding the response/recovery speed in air-relative to N or Ar. Here, we describe the preparation of H sensors in which a nanofiltration layer consisting of a Zn metal-organic framework (MOF) is assembled onto Pd NWs. Polyhedron particles of Zn-based zeolite imidazole framework (ZIF-8) were synthesized on lithographically patterned Pd NWs, leading to the creation of ZIF-8/Pd NW bilayered H sensors. The ZIF-8 filter has many micropores (0.34 nm for gas diffusion) which allows for the predominant penetration of hydrogen molecules with a kinetic diameter of 0.289 nm, whereas relatively larger gas molecules including oxygen (0.345 nm) and nitrogen (0.364 nm) in air are effectively screened, resulting in superior hydrogen sensing properties. Very importantly, the Pd NWs filtered by ZIF-8 membrane (Pd NWs@ZIF-8) reduced the H response amplitude slightly (ΔR/R = 3.5% to 1% of H versus 5.9% for Pd NWs) and showed 20-fold faster recovery (7 s to 1% of H) and response (10 s to 1% of H) speed compared to that of pristine Pd NWs (164 s for response and 229 s for recovery to 1% of H). These outstanding results, which are mainly attributed to the molecular sieving and acceleration effect of ZIF-8 covered on Pd NWs, rank highest in H sensing speed among room-temperature Pd-based H sensors.
空气中的氧气会干扰基于钯（Pd）的 H 传感器（包括 Pd 纳米线（NWs））对 H 的检测，从而降低其在空气环境中的灵敏度，并减缓其对 H 的响应/恢复速度，相对于 N 或 Ar 而言。在此，我们描述了一种 H 传感器的制备方法，其中由纳米过滤层组成的锌金属有机骨架（MOF）被组装到 Pd NWs 上。在光刻图案化的 Pd NWs 上合成了多面体颗粒的基于沸石咪唑骨架（ZIF-8），从而产生了 ZIF-8/Pd NW 双层 H 传感器。ZIF-8 过滤器具有许多微孔（气体扩散的 0.34nm），允许具有 0.289nm 动力学直径的氢分子主要渗透，而相对较大的气体分子（包括空气中的氧气（0.345nm）和氮气（0.364nm））则被有效阻挡，从而产生优异的氢气传感性能。非常重要的是，由 ZIF-8 膜过滤的 Pd NWs（Pd NWs@ZIF-8）对 H 的响应幅度略有降低（ΔR/R = 3.5%对 H 与 Pd NWs 的 5.9%相比），并且与原始 Pd NWs 相比，恢复速度（10s 至 1%的 H）和响应速度（10s 至 1%的 H）快 20 倍（164s 对 H 的响应和 229s 对 H 的恢复）。这些出色的结果主要归因于 ZIF-8 覆盖在 Pd NWs 上的分子筛和加速作用，在室温下基于 Pd 的 H 传感器中，其 H 传感速度最高。
