McEvoy Todd M, Long Jeffrey W, Smith Timothy J, Stevenson Keith J
Naval Research Laboratory, Surface Chemistry Branch, Code 6170, 4555 Overlook Avenue SW, Washington, DC 20375-5342, USA.
Langmuir. 2006 May 9;22(10):4462-6. doi: 10.1021/la052571g.
We use conductive-probe atomic force microscopy (CP-AFM) to characterize and image hybrid electrode structures comprising mesoporous manganese oxide (MnO2) ambigel nanoarchitectures coated with an ultrathin (<10 nm) electrodeposited layer of poly(o-phenylenediamine), PPD. Native MnO2 ambigel films, supported on indium tin oxide (ITO) substrates, exhibit spatially uniform conductivity that correlates well with the topography of the MnO2 film, confirming that the nanoscopic oxide network is effectively wired to the underlying ITO substrate. Following the self-limiting electrodeposition of the PPD coating onto the high-surface-area (>200 m2 g(-1)) MnO2 ambigel, the resulting hybrid structures display an approximately 20-fold reduction in conductivity, as determined from CP-AFM measurements. The CP-AFM imaging studies confirm that the ultrathin, insulating PPD layer conformally and homogeneously coats the conductive nanoarchitecture. CP-AFM imaging of PPD-MnO2 hybrid electrodes following electrochemical cycling in an aqueous acid electrolyte reveals that the ultrathin PPD coating serves as an effective barrier to the electrolyte, protecting the underlying MnO2 nanoarchitecture from electrochemical dissolution.
我们使用导电探针原子力显微镜（CP-AFM）来表征和成像混合电极结构，该结构由介孔氧化锰（MnO₂）气凝胶纳米结构组成，表面涂覆有一层超薄（<10 nm）的电沉积聚邻苯二胺（PPD）层。负载在氧化铟锡（ITO）衬底上的原生MnO₂气凝胶薄膜表现出空间均匀的导电性，这与MnO₂薄膜的形貌密切相关，证实了纳米级氧化物网络有效地连接到了下面的ITO衬底。在将PPD涂层自限性电沉积到高比表面积（>200 m² g⁻¹）的MnO₂气凝胶上之后，通过CP-AFM测量确定，所得混合结构的导电性降低了约20倍。CP-AFM成像研究证实，超薄绝缘PPD层以共形且均匀的方式覆盖了导电纳米结构。在水性酸性电解质中进行电化学循环后，对PPD-MnO₂混合电极进行CP-AFM成像，结果表明超薄PPD涂层可作为电解质的有效屏障，保护下面的MnO₂纳米结构不被电化学溶解。
