Abstract
This paper aimed to improve the electrochemical activity of a pitch-derived open-pore graphite foam (GF) by an electrochemical coating of reduced graphene oxide (RGO) and platinum particles without significantly affecting its 3D-structure. RGO was synthesized using cyclic voltammetry (CV) from a 3 g L−1 GO and 0.1 M LiClO4 solution. For the electrodeposition of Pt particles, an alternating current method based on electrochemical impedance spectroscopy (EIS) was used. A sinusoidal voltage from a fixed potential Ei was varied following a selected amplitude (ΔEac = ± 0.35 V) in a frequency range of 8 Hz ≤ fi ≤ 10Hz, where i = 500. This method proved its efficiency when compared to the traditional CV by obtaining more highly electroactive coatings in less synthesis time. For samples’ characterization, physical measures included permeability, pressure drop, and nitrogen adsorption isotherms. The electrochemical characterization was performed by CV. The surface morphology and chemical composition were examined using field emission electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX), respectively. RGO improved the electron transfer rate constant of GF, and a more homogeneous coating distribution of reduced size Pt particles was obtained.
Highlights
Success in the application of the replication technique, extensively used in the fabrication of metal foams, has led to the manufacture of pitch-derived open-pore foams with a high degree of graphitization
Pt mass was observed; for instance, Pt mass for GFERGO/Pt (Ei = 0.25 V) was 0.00015 g. These results was observed; for instance, Pt mass for GFERGO/Pt (Ei = 0.25 V) was 0.00015 g. These results indicated indicated that the presence of reduced graphene oxide (RGO) mainly conditioned how nuclei formation and growth of Pt that the presence of RGO mainly conditioned how nuclei formation and growth of Pt particles occurred particles occurred during synthesis rather than the amount of Pt synthetized and thereby the different during synthesis rather than the amount of Pt synthetized and thereby the different electrochemical electrochemical behavior of the electrodes
cyclic voltammetry (CV).applied, It was shown improved the electron transfer be obtained in less synthesis time than the traditional
Summary
Success in the application of the replication technique, extensively used in the fabrication of metal foams, has led to the manufacture of pitch-derived open-pore foams with a high degree of graphitization. Due to high electronic conductivity, strong resistance to acidic/alkaline environments, and enhanced accessibility of active sites, 3D porous carbonaceous materials have attracted attention as electrodes for electrocatalytic applications [3]. Graphene is a material with unique properties, such as high electrical and thermal conductivity, high electron mobility (~200,000 cm V−1 s−1 ), excellent mechanical/thermal stability, prominent stability for chemical agents, and a high surface area (2630 m2 g−1 ) [4,5,6,7]. To recover the graphitic structure and electrical conductivity of graphene, GO has to be reduced [8,9,10,11,12]. The electrochemical reduction of GO has the Coatings 2020, 10, 551; doi:10.3390/coatings10060551 www.mdpi.com/journal/coatings
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