Integration of Conducting Polymers and Metal Organic Frameworks for boosting Oxygen Reduction Reaction performance: a Nanoarchitectonics Approach

GONZALO E. FENOY; MÁRTIRE, ANA PAULA; JULIANA SCOTTO; MATÍAS RAFTI; WALDEMAR A. MARMISOLLÉ; OMAR AZZARONI

Congreso; 71th Annual meeting of the International Society of Electrochemistry; 2020

International Society of Electrochemistry

The term ?Nanoarchitectonics? involves the integration of molecular building blocks into well-defined organized assemblies via a variety of approaches, where the intimate connection between the materials gives origin to improved functionalities or even creates new ones. Among the vast spectrum of available strategies, Layer-by-Layer (LbL) and electropolymerization are two of the most employed approaches for creating functional materials for electrochemical applications. While LbL allows for an accurate manipulation of film architecture and the incorporation of numerous building blocks; electropolymerization offers a precise control of film thickness, morphology, and composition, thus allowing the inclusion of desired moieties for further surface functionalization.On the other hand, Oxygen Reduction Reaction (ORR) is an essential electrochemical process in many energy conversion devices, taking particular relevance in facing the increasing global demand for clean energy sources and vectors. Desirable features for ORR-based catalysts are operability under environmentally friendly conditions, biocompatible electrolytes, and the reduction of metal loadings. [1]Having in mind the above discussion, we hereby present examples of the integration of Conducting Polymers (CPs) and Metal Organic Frameworks (MOFs) through different approaches in order to construct assemblies featuring improved ORR performance. In this way, the O2 adsorption ability and high porosity of the Zn-based MOF ZIF-8, and the electroactivity of polyaniline-like CPs are effectively brought together by making use of LbL assembly and electropolymerization techniques. In the first example, the LbL strategy is employed in order to perform the sequential assembly of colloidal suspensions of the polyaniline/polystyrene sulfonate complex (Pani-PSS) and polyallylamine hydrochloride-coated ZIF-8 nanocrystals (PAH-ZIF-8). The LbL-assembled films are found to be electrically connected and feature promising increases in the ORR current in neutral pH aqueous environments.[2]On the other hand, we introduce the use of electropolymerization as synthetic strategy for producing electroactive films featuring ?NH2 moieties. Then, a MOF coating is integrated by induced growth on the amino pending moieties from the methanolic precursor solutions. This strategy generated a composite film with improved ORR performance due to the effective combination of the electroactivity of the CP and the MOF capacity of acting as an oxygen reservoir.[3] Moreover, this approach also allows the incorporation of metallic nanoparticles (NPs) in order to improve the overall electrocatalytic performance of the nanocomposites. In this way, the in-situ reduction of the Pt NPs precursor on the CP not only keeps the electroactivity of the conducting matrix but also improves its electrocatalytic efficiency. Subsequent deposition of the MOF coating further increases the ORR performance, by adding the O2 preconcentrating effect. [1]Finally, nanoarchitectonics can be seen as a toolkit from which different strategies can be taken in order to construct complex interfacial architectures with improved ORR features arising from the combination of the different building blocks.