Ternary anode electrocatalyst based membrane electrode assembly for direct methanol fuel cell
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Date
2022
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Universiti Teknologi Malaysia
Abstract
Direct methanol fuel cell (DMFC) has attracted significant attention worldwide as a sustainable energy source. The performance of DMFC mostly depends on how efficiently methanol oxidizes on the electrocatalyst surface which is one of the most important criteria for DMFC commercialization. In general, pure platinum (Pt) electrocatalyst has been widely utilized for methanol oxidation reaction (MOR) in DMFC. However, the high cost, insufficient stability and low utilization efficiency of Pt electrocatalyst due to the poisoning effect of strongly chemisorbed carbon monoxide (CO)-likes intermediate species drastically affect the electrocatalytic performance of MOR and thus reduce the DMFC performance. In this regard, an efficient anode electrocatalyst production is significantly important and required to achieve outstanding electrocatalytic performance towards MOR. Therefore, the main objective of this study was to produce a novel advanced ternary RGO/bimetallic Ptx-Pdy alloy/ZCeO2 nanocomposite electrocatalyst with enhanced electrocatalytic performance of MOR through one-step hydrothermal-assisted formic acid reduction reaction for DMFC application. The influences of different Ptx-Pdy atomic ratio namely the ternary RGO/bimetallic Ptx-Pdy alloy/ZCeO2 nanocomposite electrocatalyst with a fixed amount of ceria loading on the electrocatalytic performance towards MOR were investigated. The ternary electrocatalyst with Pt2-Pd3 atomic ratio was found to be the optimum electrocatalyst based on its higher overall electrocatalytic performance towards MOR. Subsequently, the optimum nanocomposite electrocatalyst was modified by studying the various amount of ceria (CeO2) loading toward the electrocatalytic performance of MOR. The resultant ternary RGO/bimetallic Pt2-Pd3 alloy/0.45CeO2 electrocatalyst was identified as the best nanocomposite formulation and presented a very outstanding electrocatalytic performance with the highest maximum forward peak current density (56.81 mA cm−2) than those of the ternary electrocatalysts with different ceria loading toward MOR in acidic medium. Moreover, the ternary RGO/bimetallic Pt2-Pd3 alloy/0.45CeO2 electrocatalyst also possessed excellent stability and exceptional poisoning tolerance during MOR. The obtained ternary nanocomposite electrocatalyst was extensively characterized to confirm the formation, deposition and homogenous distribution of Pt2-Pd3 alloy and CeO2 nanoparticles on the surface of RGO. Meanwhile, the DMFC performance evaluation was conducted by employing the ternary RGO/bimetallic Pt2-Pd3 alloy/0.45CeO2 electrocatalyst based membrane electrode assembly (MEA) under various operating temperatures. The highest maximum power density (95.67 mW/cm2) was obtained by the ternary RGO/bimetallic Pt2-Pd3 alloy/0.45CeO2 electrocatalyst at 60 oC with methanol concentration of 1 M. Besides, the ternary nanocomposite electrocatalyst with 40 wt% of Pt2-Pd3 loading displayed the highest power density (112.64 mW/cm2) compared to the commercial electrocatalysts (40 % Pt-Ru catalyst on carbon paper, 40 % Pt catalyst on carbon paper, and Pt black) at 60 oC and room temperature. Therefore, the remarkable electrocatalytic performance of the as-prepared ternary nanocomposite electrocatalyst with convenient experimental procedure could be used as an alternative anode electrocatalyst for DMFC application.
Description
Thesis (PhD. (Chemical Engineering))
Keywords
Electrochemical analysis—Research, Metals—Anodic oxidation, Fuel cells, Nanocomposites (Materials)