Kwon Gihan, Cho Yeong Ho, Kim Ki Bum, Emery Jonathan D, Kim In Soo, Zhang Xiaoyi, Martinson Alex B F, Tiede Davd M
Argonne Northwestern Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan Road, Tech Room L110, Evanston, IL 60208-3113, USA.
Nano Fabrication Laboratory, Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu 151-744, South Korea.
J Synchrotron Radiat. 2019 Sep 1;26(Pt 5):1600-1611. doi: 10.1107/S1600577519007240. Epub 2019 Aug 9.
Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm-50 nm crystalline indium tin oxide or a 100 nm-150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure-function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.
本文描述了多孔、高表面积的电极结构，该结构能够在与器件相关的功能性电化学条件下，利用高能X射线（>50 keV）散射和对分布函数（PDF）分析，对界面非晶薄膜进行高空间分辨率的结构表征。多孔电极由涂覆有保形透明导电氧化物层的玻璃毛细管阵列膜制成，该透明导电氧化物层由通过原子层沉积法沉积的40 nm - 50 nm结晶铟锡氧化物或100 nm - 150 nm厚的非晶铟锌氧化物组成。这些多孔电极解决了二维工作电极设计中催化剂薄膜相互作用体积不足的问题，并提供了足够低的散射背景，以实现从界面薄膜催化剂收集高分辨率信号。例如，当沉积在孔径为40 µm的多孔电极上时，对于厚度低至60 nm的非晶氧化钴薄膜，很容易获得空间分辨率为0.2 Å的PDF测量结果。这种分辨率水平能够解析钴酸盐的畴尺寸和结构、分配给畴边缘的缺陷位点的存在，以及与定量结构 - 功能建模相关的氧化还原状态变化时精细结构的变化。结果表明，利用多孔电极结构对纳米级表面支撑分子催化剂进行PDF分析具有可行性。此外，还描述了一种紧凑的三电极配置的3D打印电化学电池，其设计允许同时进行X射线透射和电解液流过多孔工作电极。
