title: Vacuum-Deposited Porphyrin Protective Films on Graphite: Electrochemical Atomic Force Microscopy Investigation during Anion Intercalation.
abstract: 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.
authors.affiliation: Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy.
authors.forename: Rossella
authors.initials: R
authors.lastname: Yivlialin
authors.affiliation: Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy.
authors.forename: Gianlorenzo
authors.identifier: http://orcid.org/0000-0001-8556-8014
authors.initials: G
authors.lastname: Bussetti
authors.affiliation: Institute of Molecular Science and Technologies of the CNR (ISTM) , PST via G. Fantoli 16/15, 20138 Milano, Italy.|SmartMatLab Centre@ISTM, Via C. Golgi 19, 20133 Milano, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Penconi
authors.affiliation: Institute of Molecular Science and Technologies of the CNR (ISTM) , PST via G. Fantoli 16/15, 20138 Milano, Italy.|SmartMatLab Centre@ISTM, Via C. Golgi 19, 20133 Milano, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Bossi
authors.affiliation: Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Ciccacci
authors.affiliation: Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Finazzi
authors.affiliation: Department of Physics, Politecnico di Milano , p.za Leonardo da Vinci 32, I-20133 Milano, Italy.
authors.forename: Lamberto
authors.initials: L
authors.lastname: Duò
keywords: anion intercalation; electrochemical AFM; graphite; porphyrins; protective film