Pt-Co3O4 Superstructures by One-Pot Reduction/Precipitation in Bicontinuous Microemulsion for Electrocatalytic Oxygen Evolution Reaction

• Published in: Catalysts Vol. 10; no. 11; p. 1311
• Main Authors: Adesuji, Elijah T., Guardado-Villegas, Esther, Fuentes, Keyla M., Sánchez-Domínguez, Margarita, Videa, Marcelo
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.11.2020
• Subjects: bicontinuous microemulsion; Catalysts; Chemical reactions; Cobalt; Cobalt oxides; Hydrogen; Kinetics; Metal oxides; Metals; metal–metal oxides; Microemulsions; Morphology; Nanochannels; Nanomaterials; Nanoparticles; Oxidation; oxygen evolution reaction; Oxygen evolution reactions; Platinum; Population; Porous materials; Precursors; Spectrum analysis; Superstructures; Tafel slopes; Voltammetry
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal10111311

Bicontinuous microemulsions (BCME) were used to synthesize hierarchical superstructures (HSs) of Pt-Co3O4 by reduction/precipitation. BCMEs possess water and oil nanochannels, and therefore, both hydrophilic and lipophilic precursors can be used. Thus, PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi were prepared (where Aq and Oi stand for the precursor present in aqueous or oily phase, respectively). The characterization of the Pt-Co3O4-HS confirmed the formation of metallic Pt and Co3O4 whose composition and morphology are controlled by the initial pH and precursor combination, determining the presence of the reducing/precipitant species in the reaction media. The electrocatalytic activity of the Pt-Co3O4-HSs for oxygen evolution reaction (OER) was investigated using linear sweep voltammetry in 0.1 M KOH and compared with Pt-HS. The lowest onset overpotentials for Pt-Co3O4-Hs were achieved with PtOi-CoOi (1.46 V vs. RHE), while the lowest overpotential at a current density of 10 mA cm−2 (η10) was obtained for the PtAq-CoAq (381 mV). Tafel slopes were 102, 89, 157 and 92 mV dec−1, for PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi, respectively. The Pt-Co3O4-HSs showed a better performance than Pt-HS. Our work shows that the properties and performance of metal–metal oxide HSs obtained in BCMEs depend on the phases in which the precursors are present.