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|
| Type |
Oral Presentation |
| Area |
Oral Presentation of Young Scholars in Electrochemistry |
| Room No. |
Room 320 |
| Time |
THU 09:45-: |
| Code |
ELEC.O-4 |
| Subject |
Controlled synthesis and characterization of Pd-based catalysts with enhanced electrocatalytic activity toward ORR/OER |
| Authors |
Anh.T.N Nguyen, Jun Ho Shim*
Department of Chemistry, Daegu University, Korea
|
| Abstract |
Considering global energy scenarios, oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the most important electrochemical reactions. An important concern in the scientific community to develop low-cost, active and stable ORR and OER catalysts is due to the fact that both Pt and Ir are expensive and rare. Alternatively, the design of highly active and stable catalysts using Pd and Pd-based nanomaterials has focused attention more recently due to the relatively high ORR activity, stability, greater abundance and almost half the cost of Pt. Thus, we report an efficient synthesis of size and shape-controlled Pd nanostructure in aqueous solution and their electrocatalytic activity for ORR. The proposed synthesis was examined using L-ascorbic acid as a reducing agent of Pd(II) in the presence of both a stabilizer and a capping agent such as Pluronic F127. The resultant Pd nanoparticles have different sizes, while their shapes can be controlled by using Pluronic F127 : halide anions (Cl-, Br-, I-) with different aspect ratios. On the other hand, iridium, as a second metallic element, is not only the best catalyst for the OER but also an excellent transition metal component to improve catalysis because it can form oxygen species on the surface at relatively low potentials. To lower the cost, several studies have focused on minimizing the use of Ir for improving the electrocatalytic activity of Ir-based nanomaterials. This presentation introduces a facile one-step process to synthesize highly interconnected nanoporous Ir-Pd alloys supported on carbon that exhibit excellent bifunctional electrocatalytic activities for both the ORR and OER with reasonable stability in alkaline electrolytes. The nanoporous Pd networks with crystalline {111} faces are shown experimentally to serve mainly as active sites for the ORR, whereas the Ir nanoparticles incorporated in the Pd nanoframe networks, where the optimized Ir : Pd ratio was 0.23 : 0.77 (n = 10), were responsible for the OER. Such three-dimensional architectures provide a high density of active sites for the oxygen electrochemical reaction and facilitate electron transport. More importantly, the nanoporous Ir-Pd alloy nanocomposites exhibited similar stability for the oxygen reduction reaction but superior catalytic activity to the commercial Pd catalyst in alkaline solutions. In addition, the materials were also highly active for the oxygen evolution reaction, e.g., a small overpotential at 10 mA cm-2 (1.628 V vs. reversible hydrogen electrode), making it a high-performance bifunctional catalyst for both the oxygen electrochemical reaction. Rotating ring-disk electrode measurements showed that the ORR and OER on the Ir-Pd catalysts proceeded predominantly through the desired 4-electron pathway. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2016R1D1A1B03930895). |
| E-mail |
anhnguyentn@daegu.ac.kr |
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122nd General Meeting of the KCS