Powering up the Oxygen Reduction Reaction through the Integration of O2-adsorbing Metal-Organic Frameworks on Nanocomposite Electrodes

FENOY, GONZALO EDUARDO; SCOTTO, JULIANA; AZCÁRATE, JULIO C.; RAFTI, MATIAS; MARMISOLLÉ, WALDEMAR ALEJANDRO; AZZARONI, OMAR

ACS Applied Energy Materials

AMERICAN CHEMICHAL SOC

Lugar: Washington; Año: 2018

2574-0962

Oxygen reduction reaction (ORR), essential inmany energy conversion devices, takes particular relevance infacing the increasing global demand for clean energy sourcesand vectors. In this context, desirable features for ORR-basedelectrochemical cells are operability under environmentallyfriendly conditions, such as pH 7 biocompatible electrolytes,and the usage of relatively low electrocatalyst loadings. On theother hand, the improvement of the cathode performance inneutral solutions is commonly focused on the development ofelectrocatalyzers for reducing the ORR overpotential. In thiswork, we took advantage of the possibilities brought by a novel strategy toward construction of complex interfacial architectures,the so-called ?nanoarchitectonics? approach. In order to achieve enhanced ORR currents and reduced overpotentials, wecombined three different building blocks with defined functionalities: a conducting polymer (CP) nanofilm (the connectingelectroactive matrix), well dispersed Pt-nanoparticles (the electrocatalyzer), and a layer of a Zn-based metal−organic framework(MOF) nanocrystals (the in situ oxygen reservoir). The sequential synthetic procedure includes the electrosynthesis of apolyaniline-like electroactive film, the synthesis of Pt nanoparticles within this film, and the deposition of a layer of MOFnanocrystals, which adds micro/mesoporosity to the assembly. The incorporation of the MOF nanocrystals layer incorporatestwo fundamental aspects: it allows for the ionic transport through its interparticle interstices, and also selectively promotes theO2 preconcentration, which is then available for the ORR on the embedded catalytically active metallic nanoparticles. Therational integration of these blocks yields a functional interfacial architecture for enhanced ORR currents in eco-friendly neutralpH KCl solutions.