Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy.
Institute of Molecular Science and Technologies of the CNR (ISTM) , PST via G. Fantoli 16/15, 20138 Milano, Italy.
ACS Appl Mater Interfaces. 2017 Feb 1;9(4):4100-4105. doi: 10.1021/acsami.6b12359. Epub 2017 Jan 18.
The development of graphene products promotes a renewed interest toward the use of graphite in addition to the historical one for its proven viability as battery electrode. However, when exposed to harsh conditions, the graphite surface ages in ways that still need to be fully characterized. In applications to batteries, to optimize the electrode performances in acid solutions, different surface functionalizations have been studied. Among them, aromatic molecules have been recently proposed. In this communication, we report on the protective effect exerted by a physical-vapor-deposited porphyrin layer. Metal-free tetra-phenyl-porphyrins were deposited on a highly oriented pyrolytic graphite crystal to study the modifications that occur during anion intercalation in graphite. The graphite electrode was plunged in an electrolyte solution of 1 M sulfuric acid and subjected to cyclic voltammetry. The results indicate that blister formation, the characteristic swelling of graphite surface induced by anion intercalation, is significantly perturbed by the porphyrin overlayer; the process is inhibited in those areas where the protective porphyrin film is present. We ascribe the inhibition of the anion intercalation to the protective porphyrin wetting layer.
石墨烯产品的发展促使人们重新关注石墨的应用，除了其作为电池电极的可行性之外，石墨在历史上也一直被证明是可行的。然而，当暴露在恶劣的条件下时，石墨表面会以仍需充分表征的方式老化。在电池应用中，为了优化电极在酸性溶液中的性能，已经研究了不同的表面功能化。其中，最近提出了芳香族分子。在本通讯中，我们报告了由物理气相沉积卟啉层施加的保护作用。将金属自由的四苯基卟啉沉积在高度取向的热解石墨晶体上，以研究在石墨中阴离子嵌入过程中发生的修饰。将石墨电极浸入 1 M 硫酸的电解质溶液中，并进行循环伏安法测试。结果表明，泡形成，即阴离子嵌入引起的石墨表面的特征膨胀，被卟啉覆盖层显著干扰；在存在保护性卟啉膜的区域，该过程被抑制。我们将阴离子嵌入的抑制归因于保护性卟啉润湿层。
