Castro Carmen, Arancibia-Miranda Nicolas, Acuña-Rougier Cristina, Escudey Mauricio, Tasca Federico
Department of Chemistry of Materials, University of Santiago of Chile, 9170022 Santiago, Chile.
Center for the Development of Nanoscience and Nanotechnology, CEDENNA, 9170022 Santiago, Chile.
Nanomaterials (Basel). 2016 Feb 2;6(2):28. doi: 10.3390/nano6020028.
Carbon nanotubes and other forms of carbon nanoparticles, as well as metal nanoparticles have been widely used in film electrochemistry because they allow for the immobilization of larger amounts of catalyst (either biological or inorganic) on the top of the modified electrodes. Nevertheless, those nanoparticles present high costs of synthesis and of separation and purification that hamper their employment. On the other hand, imogolites (Im), with the general formula (OH)₃Al₂O₃SiOH, are naturally-occurring nanomaterials, which can be obtained from glassy volcanic ash soils and can also be synthesized at mild conditions. In this research paper, we characterize through spectroscopic techniques (., fourier transform infrared spectroscopy (FTIR) spectroscopy, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM)) synthetized Im and Fe-modified imogolite (Im(Fe)). Moreover, the Im and Im(Fe) were physically adsorbed on the top of a graphite electrode (GE) and were characterized electrochemically in the potential region ranging from -0.8 to 0.8 V the saturated calomel electrode (SCE). When the film of the Im or of the Im(Fe) was present on the top of the electrode, the intensity of the charging/discharging current increased two-fold, but no redox activity in the absence of O₂ could be appreciated. To show that Im and Im(Fe) could be used as support for catalysts, iron phthalocyanine (FePc) was adsorbed on the top of the Im or Im(Fe) film, and the electrocatalytic activity towards the O₂ reduction was measured. In the presence of the Im, the measured electrocatalytic current for O₂ reduction increased 30%, and the overpotential drastically decreased by almost 100 mV, proving that the Im can act as a good support for the electrocatalysts.
碳纳米管和其他形式的碳纳米颗粒以及金属纳米颗粒已广泛应用于薄膜电化学领域，因为它们能使大量催化剂（生物催化剂或无机催化剂）固定在修饰电极表面。然而，这些纳米颗粒的合成、分离和纯化成本高昂，这限制了它们的应用。另一方面，伊莫石（Im），通式为(OH)₃Al₂O₃SiOH，是一种天然存在的纳米材料，可从玻璃质火山灰土壤中获取，也能在温和条件下合成。在本研究论文中，我们通过光谱技术（如傅里叶变换红外光谱（FTIR）、粉末X射线衍射（XRD）和透射电子显微镜（TEM））对合成的伊莫石和铁修饰伊莫石（Im(Fe)）进行了表征。此外，将伊莫石和Im(Fe)物理吸附在石墨电极（GE）表面，并在相对于饱和甘汞电极（SCE）为 -0.8至0.8 V的电位范围内进行电化学表征。当电极表面存在伊莫石或Im(Fe)薄膜时，充电/放电电流强度增加了两倍，但在没有O₂的情况下未观察到氧化还原活性。为了表明伊莫石和Im(Fe)可用作催化剂载体，将铁酞菁（FePc）吸附在伊莫石或Im(Fe)薄膜表面，并测量了其对O₂还原的电催化活性。在有伊莫石存在的情况下，测得的O₂还原电催化电流增加了30%，过电位急剧降低了近100 mV，证明伊莫石可作为电催化剂的良好载体。
