Gold nanoparticles modified cobalt iron oxide inverse opals as high-performance oxygen reduction electrocatalyst Thi Hong Trang Nguyen * , Chinnabathini Vana Chinnappa, Didier Grandjean and Ewald Janssens Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven, Belgium *thihongtrang.nguyen@kuleuven.be Exploration of competitive electrocatalysts to replace high-performance but high-cost Pt-based catalysts for oxygen reduction reaction (ORR) in fuel cells is an important strategy to confront energy and environmental crises. Although Fe, Co, and Ni-based catalysts have demonstrated good ORR catalytic activity, they generally lack stability in harsh environments as these metals can dissolve in an acidic or basic solution. Using their oxides 1,2 and carbides/nitrides 3,4 compounds instead has allowed significant improvements for the ORR by reducing metal dissolution. Introducing gold in these systems can also significantly enhance their activity, long-term durability and mitigate their dissolution. 5,6 We have recently produced mesoporous cobalt iron oxide inverse opals ( m -CFO IO) directly grown on nickel foam using polystyrene beads as a hard template followed by calcination in air. Their mesoporous structure featuring a high surface area demonstrated promising performance in the ORR. The performance of m -CFO IO can be significantly enhanced by modifying their surface with well- defined gas-phase Au NPs. Preformed Au nanoparticles of ca. 2 nm diameter have been deposited in soft landing mode using the cluster beam deposition (CBD) technology on m -CFO IO with loadings ranging from 4 to 10 atomic monolayers (ML). As-prepared m -CFO/Au IO samples were characterized with scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical methods. m -CFO/Au IO catalysts with an optimal gold loading of 7 ML exhibit an excellent ORR performance with the highest onset potential of 0.87 V and halfwave potential of 0.79 V vs. RHE. A remarkable three-time increase of the kinetic current density at 0.7 V and a halfwave potential shift of 180 mV are reported compared with their non- modified counterparts with long-term stability in both half-cell and single-cell accelerated degradation tests. The observed catalytic behavior enhancements that strongly depend on the Au mass loading deposited on the m -CFO IO are expected to arise from the sample’s large surface area and the synergistic effect of Au NPs and the m -CFO that guarantee a large number of accessible catalytic sites and rapid mass-transfer kinetics. References 1. Cheng, J. Shen, B. Peng, Y. Pan, Z. Tao and J. Chen, Nat. Chem., 2011, 3, 79–84
2. Wang, Y. Li, T. Jin, J. Meng, L. Jiao, M. Zhu and J. Chen, Nano Lett., 2017, 17, 7989–7994. 3. Hu, X. Y. Yu, F. Chen, Y. Wu, Y. Hu and X. W. Lou, Adv. Energy Mater., 2017, 1702476 4. Fan, Z. Peng, R. Ye, H. Zhou and X. Guo, ACS Nano, 2015, 9, 7407–7418 5. Gatalo, P. Jovanovic, G. Polymeros, M. Gabersc. ACS Catal. 2016, 6 (3), 1630−1634 6. Choi, C. W. Roh, B. S. Kim, H. Lee. Appl. Catal., B 2019, 247, 142−149
P13
© The Author(s), 2022
Made with FlippingBook Learn more on our blog