Chen Huaming, Wang Xiaolong, Ma Bangjun, Wang Hanbin, Chen Yi, Jiang Chunli, Huang Guoqiang, Kou Huaqin, Tang Tao, Luo Deli
Institute of Materials, China Academy of Engineering Physics, Jiangyou, Mianyang 621907 Sichuan, P. R. China.
Microsystem & Terahertz Research Center, China Academy of Engineering Physics, Chengdu, 610200 Sichuan, P. R. China.
ACS Appl Mater Interfaces. 2022 Jul 27;14(29):33686-33693. doi: 10.1021/acsami.2c05525. Epub 2022 Jul 18.
Monitoring conductivity changes of discontinuous palladium (Pd) nanostructures upon hydrogenation is becoming one of the most promising approaches toward hydrogen sensing. Development of sensors in this type has long been impeded due to strong ubiquitous interfacial adhesion which could distinctly restrict Pd expansion so as to hinder the closing of a nanogap. Herein, graphene underlayers were applied in the fabrication of nanogap-based hydrogen sensors to promote the lateral expansion of a Pd nanowire upon hydrogenation by reducing the adhesion between the metal and the substrate. In order to clarify details as well as mechanisms underlaid of graphene-enhanced Pd expansion, nanowire samples with serial lengths (6-48 μm) and gaps (0-260 nm in width) were controllably prepared on single-layer graphene (SLG), double-layer graphene (DLG), and quadruple-layer graphene (QLG, DLG × 2) via the combination of electron beam lithography (EBL) and electron beam deposition (EBD) technology. Response features and intrinsic analysis in physical sense of the graphene-based discontinuous Pd circuits upon hydrogen were established, in light of which the effects of underlayers on Pd expansion and on nanogap closing process were investigated. Such graphene-promoted expansion was demonstrated through the achievement of the closure of a large gap threshold () up to 260 nm as well as the systematical investigation of its influence on the sensing performance.
监测氢化过程中不连续钯（Pd）纳米结构的电导率变化正成为最有前途的氢传感方法之一。由于普遍存在的强界面附着力，这种类型的传感器的开发长期以来受到阻碍，这种附着力会明显限制钯的膨胀，从而阻碍纳米间隙的闭合。在此，石墨烯底层被应用于基于纳米间隙的氢传感器的制造中，通过减少金属与衬底之间的附着力来促进氢化过程中钯纳米线的横向膨胀。为了阐明石墨烯增强钯膨胀的细节和潜在机制，通过电子束光刻（EBL）和电子束沉积（EBD）技术的结合，在单层石墨烯（SLG）、双层石墨烯（DLG）和四层石墨烯（QLG，DLG×2）上可控地制备了具有系列长度（6-48μm）和间隙（宽度0-260nm）的纳米线样品。建立了基于石墨烯的不连续钯电路在氢气作用下的响应特征和物理意义上的本征分析，并据此研究了底层对钯膨胀和纳米间隙闭合过程的影响。通过实现高达260nm的大间隙阈值（）的闭合以及对其对传感性能影响的系统研究，证明了这种石墨烯促进的膨胀。
