In Situ SERS Study of Electrocatalytic CO₂RR on Au@Pd Bimetallic Catalysts: From Isolated Single Atoms to Monolayer of Pd

Abstract

A fundamental understanding of catalytic activity and mechanism for electrocatalytic CO₂ reduction reaction (CO₂RR) from a single-metal atom to its monolayer on another metal substrate is crucial for bimetallic catalysts design. Herein, in situ surface-enhanced Raman scattering (SERS) spectroscopy systematically probed electrocatalytic CO₂RR on Au@Pd catalysts with varying Pd coverage, from isolated single-Pd atoms and Pd nanoislands to Pd monolayers on Au surfaces. In situ SERS sensitively detected the adsorption behavior of *CO intermediate, which, combined with electrocatalytic performance, reveals that isolated Pd single atoms on Au show the best activity for CO₂-to-CO conversion and can enhance the activity of nearby Au sites. This is attributed to the moderate energy of *COOH formation and *CO desorption on single-Pd atoms as corroborated by calculations. Moreover, we observed different potential-dependent behavior of *CO adsorbed on Pd nanoisland and monolayer surfaces. Theoretical results suggest that surface *H on Pd reverses the binding energy of *CO(atop) and *CO(bridge) at Pd step edge sites, making *CO(atop) more favorable, whereas *CO(bridge) is more stable without *H adsorption. This reveals the important role of *H in regulating intermediate adsorption configurations during CO₂RR. These observations are valuable for fine-tuning the atomic structure of bimetallic catalysts with suitable *H and *CO absorption properties for high CO₂RR performance.

Keywords

bimetallic catalysts / CO₂ reduction reaction (CO₂RR) / in situ surface enhanced Raman scattering (SERS)

References

[1] Y. Y. Birdja, E. Pérez-Gallent, M. C. Figueiredo, A. J. Göttle, F. Calle-Vallejo, and M. T. M. Koper, “Advances and Challenges in Understanding the Electrocatalytic Conversion of Carbon Dioxide to Fuels,” Nature Energy 4 (2019): 732–745.

[2] H. Yang, N. Guo, S. Xi, et al., “Potential-driven structural distortion in cobalt phthalocyanine for electrocatalytic CO₂/CO reduction towards methanol,” Nature Communications 15 (2024): 7703.

[3] D. U. Nielsen, X.-M. Hu, K. Daasbjerg, and T. Skrydstrup, “Chemically and Electrochemically Catalysed Conversion of CO2 to CO With Follow-Up Utilization to Value-Added Chemicals,” Nature Catalysis 1 (2018): 244–254.

[4] Q. Liu, L. Wu, R. Jackstell, and M. Beller, “Using Carbon Dioxide as a Building Block in Organic Synthesis,” Nature Communications 6 (2015): 5933.

[5] M. Cokoja, C. Bruckmeier, B. Rieger, W. A. Herrmann, and F. E. Kuhn, “Transformation of Carbon Dioxide With Homogeneous Transition-Metal Catalysts: A Molecular Solution to a Global Challenge?,” Angewandte Chemie International Edition 50 (2011): 8510–8537.

[6] J. De Ruiter, H. An, L. Wu, et al., “Probing the Dynamics of Low-Overpotential CO₂-to-CO Activation on Copper Electrodes With Time-Resolved Raman Spectroscopy,” Journal of the American Chemical Society 144 (2022): 15047–15058.

[7] J. Chen, H. Qiu, Y. Zhao, et al., “Selective and stable CO₂ electroreduction at high rates via control of local H₂O/CO₂ ratio,” Nature Communications 15 (2024): 5893.

[8] W. Sheng, S. Kattel, S. Yao, et al., “Electrochemical Reduction of CO₂ to Synthesis Gas With Controlled CO/H₂ Ratios,” Energy & Environmental Science 10 (2017): 1180–1185.

[9] Y. Wang, L. Cao, N. J. Libretto, et al., “Ensemble Effect in Bimetallic Electrocatalysts for CO₂ Reduction,” Journal of the American Chemical Society 141 (2019): 16635–16642.

[10] Y. Zhao, X. Liu, J. Chen, et al., “Promote electroreduction of CO₂ via catalyst valence state manipulation by surface-capping ligand,” Proceedings of the National Academy of Sciences of the United States of America 120 (2023): e2218040120.

[11] A. Goyal, G. Marcandalli, V. A. Mints, and M. T. M. Koper, “Competition Between CO₂ Reduction and Hydrogen Evolution on a Gold Electrode Under Well-Defined Mass Transport Conditions,” Journal of the American Chemical Society 142 (2020): 4154–4161.

[12] X. Yuan, L. Zhang, L. Li, et al., “Ultrathin Pd–Au Shells With Controllable Alloying Degree on Pd Nanocubes Toward Carbon Dioxide Reduction,” Journal of the American Chemical Society 141 (2019): 4791–4794.

[13] A. Pedersen, J. Barrio, A. Li, et al., “Dual-Metal Atom Electrocatalysts: Theory, Synthesis, Characterization, and Applications,” Advanced Energy Materials 12 (2021): 2102715.

[14] C. Zhu, J. Zeng, J. Tao, et al., “Kinetically Controlled Overgrowth of Ag or Au on Pd Nanocrystal Seeds: From Hybrid Dimers to Nonconcentric and Concentric Bimetallic Nanocrystals,” Journal of the American Chemical Society 134 (2012): 15822–15831.

[15] K. Wei, H. Lin, X. Zhao, et al., “Au/Pt Bimetallic Nanowires With Stepped Pt Sites for Enhanced C–C Cleavage in C2+ Alcohol Electro-Oxidation Reactions,” Journal of the American Chemical Society 145 (2023): 19076–19085.

[16] T. Zheng, C. Liu, C. Guo, et al., “Copper-Catalysed Exclusive CO₂ to Pure Formic Acid Conversion via Single-Atom Alloying,” Nature Nanotechnology 16 (2021): 1386–1393.

[17] J. Li, H. Zeng, X. Dong, et al., “Selective CO₂ Electrolysis to CO Using Isolated Antimony Alloyed Copper,” Nature Communications 14 (2023): 340.

[18] H. Li, L. Wang, Y. Dai, et al., “Synergetic Interaction Between Neighbouring Platinum Monomers in CO₂ Hydrogenation,” Nature Nanotechnology 13 (2018): 411–417.

[19] A. Klinkova, P. De Luna, C.-T. Dinh, et al., “Rational Design of Efficient Palladium Catalysts for Electroreduction of Carbon Dioxide to Formate,” ACS Catalysis 6 (2016): 8115–8120.

[20] W. Zhu, R. Michalsky, O. Metin, et al., “Monodisperse Au Nanoparticles for Selective Electrocatalytic Reduction of CO₂ to CO,” Journal of the American Chemical Society 135 (2013): 16833–16836.

[21] M. Valenti, N. P. Prasad, R. Kas, et al., “Suppressing H₂ Evolution and Promoting Selective CO₂ Electroreduction to CO at Low Overpotentials by Alloying Au With Pd,” ACS Catalysis 9 (2019): 3527–3536.

[22] J.-H. Zhong, X. Jin, L. Meng, et al., “Probing the Electronic and Catalytic Properties of a Bimetallic Surface With 3 Nm Resolution,” Nature Nanotechnology 12 (2017): 132–136.

[23] J. Wei, S.-N. Qin, J. Yang, et al., “Probing Single-Atom Catalysts and Catalytic Reaction Processes by Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy,” Angewandte Chemie, International Edition 60 (2021): 9306–9310.

[24] Y. Wu and D. Qin, “In Situ Atomic-Level Tracking of Heterogeneous Nucleation in Nanocrystal Growth With an Isocyanide Molecular Probe,” Journal of the American Chemical Society 140 (2018): 8340–8349.

[25] J. Hu, N. Hoshi, K. Uosaki, and K. Ikeda, “Vibrational Spectroscopic Observation of Atomic-Scale Local Surface Sites Using Site-Selective Signal Enhancement,” Nano Letters 15 (2015): 7982–7986.

[26] J. Wei, Y.-J. Zhang, S.-N. Qin, et al., “Understanding the Strain Effect of Au@Pd Nanocatalysts by In Situ Surface-Enhanced Raman Spectroscopy,” Chemical Communications 55 (2019): 8824–8827.

[27] X. Chang, S. Vijay, Y. Zhao, N. J. Oliveira, K. Chan, and B. Xu, “Understanding the Complementarities of Surface-Enhanced Infrared and Raman Spectroscopies in CO Adsorption and Electrochemical Reduction,” Nature Communications 13 (2022): 2656.

[28] H. Zhang, C. Wang, H.-L. Sun, et al., “In Situ Dynamic Tracking of Heterogeneous Nanocatalytic Processes by Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy,” Nature Communications 8 (2017): 15447.

[29] F. Gao, Y. Wang, and D. W. Goodman, “CO Oxidation Over AuPd(100) From Ultrahigh Vacuum to Near-Atmospheric Pressures: The Critical Role of Contiguous Pd Atoms,” Journal of the American Chemical Society 131 (2009): 5734–5735.

[30] S. Duan, P.-P. Fang, F.-R. Fan, et al., “A Density Functional Theory Approach to Mushroom-Like Platinum Clusters on Palladium-Shell Over Au Core Nanoparticles for High Electrocatalytic Activity,” Physical Chemistry Chemical Physics 13 (2011): 5441–5449.

[31] P.-P. Fang, S. Duan, X.-D. Lin, et al., “Tailoring Au-Core Pd-Shell Pt-Cluster Nanoparticles for Enhanced Electrocatalytic Activity,” Chemical Science 2 (2011): 531–539.

[32] D. Gao, H. Zhou, F. Cai, et al., “Switchable CO₂ Electroreduction via Engineering Active Phases of Pd Nanoparticles,” Nano Research 10 (2017): 2181–2191.

[33] P. Zhang, Y. Wei, J. Cai, Y.-X. Chen, and Z.-Q. Tian, “Nonlinear Stark Effect Observed for Carbon Monoxide Chemisorbed on Gold Core/Palladium Shell Nanoparticle Film Electrodes, Using In Situ Surface-Enhanced Raman Spectroscopy,” Chinese Journal of Catalysis 37 (2016): 1156–1165.

[34] T.-W. Jiang, Y.-W. Zhou, X.-Y. Ma, et al., “Spectrometric Study of Electrochemical CO₂ Reduction on Pd and Pd-B Electrodes,” ACS Catalysis 11 (2021): 840–848.

[35] M. Arenz, V. Stamenkovic, T. J. Schmidt, K. Wandelt, P. N. Ross, and N. M. Markovic, “CO Adsorption and Kinetics on Well-Characterized Pd Films on Pt(111) in Alkaline Solutions,” Surface Science 506 (2002): 287–296.

[36] Y. Zheng, X. Zhong, Z. Li, and Y. Xia, “Successive, Seed-Mediated Growth for the Synthesis of Single-Crystal Gold Nanospheres With Uniform Diameters Controlled in the Range of 5–150 Nm,” Particle & Particle Systems Characterization 31 (2013): 266–273.

[37] D. He, “Removal of Silicon-Containing Contaminants From TEM Specimens,” Ultramicroscopy 253 (2023): 113797.

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2025 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.