Wang Jianren, Vilà Neus, Walcarius Alain
Laboratoire de Chimie Physique et Microbiologie pour les Matériaux et l'Environnement (LCPME), UMR 7564 CNRS-Université de Lorraine, 405 rue de Vandoeuvre, 54600 Villers-lès-Nancy, France.
ACS Appl Mater Interfaces. 2020 May 27;12(21):24262-24270. doi: 10.1021/acsami.0c03650. Epub 2020 May 15.
Organic-inorganic hybrid membranes, made of a high density of redox active moieties covalently bonded to the internal surfaces of vertically aligned mesoporous silica thin films, are relevant for applications in transparent energy storage devices. This is demonstrated here on the basis of functionalized transparent mesoporous silica thin films prepared on the indium-tin oxide electrode from the combination of an electrochemically induced self-assembly method (to generate azide-functionalized silica) and a copper-catalyzed azide-alkyne click reaction (to derivatize the material with electroactive groups). The very small thickness (105 nm) and the uniformly distributed vertical mesochannels with ultranarrow diameter (2 nm) make the hybrid film a promising substrate that not only achieves a transparency of 82% but also provides large surface area to accommodate a high density of redox active species such as ferrocene. In such rigid and insulating porous membranes, the charge transfer reactions take place through a pure electron-hopping mechanism between adjacent redox sites, which are favored by the ordered and oriented mesostructure containing large amounts of uniformly distributed ferrocene functions in the mesochannels. Their performance results from both high charge transfer rates (electron hopping) and easy mass transport (fast diffusion of counter ions). The most effective system is the ferrocene-functionalized silica film prepared from 40% organosilane, which is able to deliver a capacity of 105 C cm (1.10 mC cm) at a current density of 0.4 A cm (with up to 48% capacity retention achieved at a charging time as short as 2.8 s). Such an electrode can be associated to an electrodeposited graphene anode in a solid-state battery-capacitor hybrid device, which can deliver 0.74 mC cm at a potential scan rate of 20 mV s. The azide-functionalized mesoporous silica film is actually a versatile platform that can be functionalized with different redox molecules, as shown here for cobaltocenium moieties, which may broaden its application field.
有机-无机杂化膜由高密度的氧化还原活性基团共价键合到垂直排列的介孔二氧化硅薄膜内表面制成，在透明储能器件中具有应用价值。本文基于在氧化铟锡电极上制备的功能化透明介孔二氧化硅薄膜进行了论证，该薄膜通过电化学诱导自组装方法（生成叠氮基功能化二氧化硅）和铜催化的叠氮-炔点击反应（用电子活性基团衍生化材料）相结合制备而成。极薄的厚度（105纳米）以及直径超窄（2纳米）且均匀分布的垂直介孔通道，使这种杂化膜成为一种有前景的基底，它不仅能实现82%的透明度，还能提供大表面积以容纳高密度的氧化还原活性物种，如二茂铁。在这种刚性且绝缘的多孔膜中，电荷转移反应通过相邻氧化还原位点之间纯粹的电子跳跃机制发生，有序且定向的介观结构有利于电荷转移，该结构在介孔通道中含有大量均匀分布的二茂铁官能团。它们的性能源于高电荷转移速率（电子跳跃）和容易的质量传输（抗衡离子的快速扩散）。最有效的体系是由40%有机硅烷制备的二茂铁功能化二氧化硅薄膜，在0.4 A/cm²的电流密度下能够提供105 C/cm²（1.10 mC/cm²）的容量（在短至2.8秒的充电时间下容量保持率高达48%）。这样的电极可以与固态电池-电容器混合器件中的电沉积石墨烯阳极结合，在20 mV/s的电位扫描速率下能够提供0.74 mC/cm²。叠氮基功能化介孔二氧化硅薄膜实际上是一个通用平台，可以用不同的氧化还原分子进行功能化，此处以钴茂基团为例，这可能会拓宽其应用领域。
