González-Lavín Judith, Arenillas Ana, Rey-Raap Natalia
Instituto de Ciencia y Tecnología del Carbono, INCAR-CSIC, 33011 Oviedo, Spain.
Gels. 2025 Feb 20;11(3):154. doi: 10.3390/gels11030154.
Metal nanoparticles supported in carbon materials are the traditional electrocatalyst currently used in many applications. However, these composite materials have many problems associated with the optimization of both components for the specific application, besides the stability of the mixture. Self-supported metallic materials may be an interesting strategy in order to avoid the traditional carbon supports; however, these metallic materials should present highly active surface area. Iron aerogels are presented in this work as effective and affordable unsupported electrocatalysts. The combination of their metallic structure with high porosity (i.e., 85 m g and 0.45 cm g of mesopore volume), due to their interconnected tridimensional structure, leads to a great activity versus the oxygen reduction reaction. A method for producing iron aerogels based on microwave-assisted sol-gel methodology is presented. The incorporation of carbon functionalities to the iron aerogels seems to clearly influence the mechanism of the reaction, favoring the direct mechanism of the oxygen reduction reaction and thus notably improving the performance of the electrocatalysts. Chemical vapor deposition seems to be an adequate methodology for incorporating carbon functionalities to the transition metal structure without affecting the tridimensional network and leading to current densities over 4 mA cm and great stability even after 10,000 s.
负载于碳材料中的金属纳米颗粒是目前在许多应用中使用的传统电催化剂。然而，除了混合物的稳定性外，这些复合材料在针对特定应用对两种组分进行优化方面还存在许多问题。自支撑金属材料可能是一种避免使用传统碳载体的有趣策略；然而，这些金属材料应具有高活性表面积。在这项工作中，铁气凝胶作为有效且经济实惠的无载体电催化剂被提出。由于其相互连接的三维结构，它们的金属结构与高孔隙率（即中孔体积为85 m²/g和0.45 cm³/g）相结合，导致对氧还原反应具有很高的活性。本文提出了一种基于微波辅助溶胶 - 凝胶方法制备铁气凝胶的方法。将碳官能团引入铁气凝胶似乎明显影响反应机理，有利于氧还原反应的直接机理，从而显著提高电催化剂的性能。化学气相沉积似乎是一种将碳官能团引入过渡金属结构而不影响三维网络的合适方法，并且即使在10000秒后也能产生超过4 mA/cm²的电流密度和很高的稳定性。
