Ethanol Electro-Oxidation on Catalysts with S-ZrO2-Decorated Graphene as Support in Fuel Cell Applications

Maryam Yaldagard; Mehrdard Shahbaz; Hyoun Woo Kim; Sang Sub Kim

doi:10.3390/nano12193327

Ethanol Electro-Oxidation on Catalysts with S-ZrO₂-Decorated Graphene as Support in Fuel Cell Applications

Nanomaterials (Basel). 2022 Sep 24;12(19):3327. doi: 10.3390/nano12193327.

Authors

Maryam Yaldagard¹, Mehrdard Shahbaz², Hyoun Woo Kim³, Sang Sub Kim⁴

Affiliations

¹ Department of Chemical Engineering, Faculty of Engineering, Urmia University, Urmia 5766-151818, Iran.
² Department of Materials Science and Engineering, Faculty of Engineering, Urmia University, Urmia 5766-151818, Iran.
³ Division of Materials Science and Engineering, Hanyang University, Seoul 04763, Korea.
⁴ Department of Materials Science and Engineering, Inha University, Incheon 22212, Korea.

Abstract

Direct ethanol fuel cells (DEFCs) are considered the most suitable direct alcohol fuel cell (DAFC) in terms of safety and current density. The obstacle to DEFC commercialization is the low reaction kinetics of ethanol (C₂H₅OH) oxidation because of the poor performance of the electrocatalyst. In this study, for the first time, graphene nanoplates (GNPs) were coated with sulfated zirconium dioxide (ZrO₂) as adequate support for platinum (Pt) catalysts in DEFCs. A Pt/S-ZrO₂-GNP electrocatalyst was prepared by a new process, polyol synthesis, using microwave heating. Field emission scanning electron microscope (FESEM) imaging revealed well-dispersed platinum nanoparticles supported on the S-ZrO₂-GNP powder. Analysis of the Fourier transform infrared (FTIR) spectrometry confirmed that sulfate modified the surfaces of the sample. In X-ray diffraction (XRD), no effect of S-ZrO₂ on the crystallinity net in Pt was found. Pt/S-ZrO₂-GNP electrode outperformed those with unsulfated counterparts, primarily for the higher access with electron and proton, confirming sulfonating as a practical approach for increasing the performance, electrocatalytic activity, and carbon monoxide (CO) tolerance in an electrocatalyst. A considerable decrease in the voltage of the CO electrooxidation peak from 0.93 V for Pt/C to 0.76 V for the Pt/S-ZrO₂-GNP electrode demonstrates that the new material increases activity for CO electrooxidation. Moreover, the as-prepared Pt/S-ZrO₂-GNPs electrocatalyst exhibits high catalytic activity for the EOR in terms of electrochemical surface area with respect to Pt/ZrO₂-GNPs and Pt/C (199.1 vs. 95 and 67.2 cm².mg^-1 Pt), which may be attributed to structural changes caused by the high specific surface area of graphene nanoplates catalyst support and sulfonating effect as mentioned above. Moreover, EIS results showed that the Pt/S-ZrO₂-GNPs electrocatalyst has a lower charge transfer resistance than Pt/ ZrO₂-GNPs and Pt/C in the presence of ethanol demonstrating an increased ethanol oxidation activity and reaction kinetics by Pt/S-ZrO₂-GNPs.

Keywords: ZrO2; electrocatalyst; ethanol electro-oxidation; fuel cell; graphene.

Grants and funding

This research received no external funding.