Operando Monitoring Interfacial pH Gradients and Ion Kinetics in Proton-Coupled Electron Transfer Reactions through Dual-Loop Electrochemical Methodology

Abstract

Interfacial pH gradients significantly affect proton-coupled electron transfer (PCET) reactions, yet quantifying these dynamics under operando conditions remains challenging. Here, we present a dual-loop methodology that enables real-time, high-resolution mapping of interfacial pH fluctuations through probing hydrogen ion-specific adsorption potentials (HISAP). We effectively decouple electric field effects from genuine changes in proton activity, facilitating direct assessment of pH behavior across various electrolytes. Our results reveal that alkaline media can exhibit pH deviations over one unit at 100 mA cm⁻², while buffered neutral systems display even greater gradients (ΔpH > 6) due to slow ion transport. By combining experimental data with Nernst-Planck models, we find that ion-specific mobility and buffer capacity are key to pH regulation. A 64% reduction in pH gradients occurs with increased buffer concentration, linking theoretical predictions with operando measurements. This reliable methodology spans the full pH range and high current densities, overcoming the limitations of traditional optical and probe-based techniques and providing a universal platform for understanding interfacial ion dynamics and optimizing electrocatalyst performance in energy conversion applications.

Keywords

H⁺-specific adsorption potential (HISAP) / interfacial pH fluctuation / proton-coupled electron transfer (PCET)

References

[1] C. Costentin, M. Robert, J. M. Savéant, Chem. Rev. 2010, 110, PR1.

[2] J. M. Mayer, Annu. Rev. Phys. Chem. 2004, 55, 363.

[3] J. J. Warren, T. A. Tronic, J. M. Mayer, Chem. Rev. 2010, 110, 6961.

[4] T. Cheng, L. Wang, B. Merinov, W. A. Goddard, J. Am. Chem. Soc. 2018, 140, 7787.

[5] I. Ledezma-Yanez, W. D. Z. Wallace, P. Sebastian-Pascual, V. Climent, J. M. Feliu, M. T. M. Koper, Nat. Energy 2017, 2, 17031.

[6] S. Q. Zhu, X. P. Qin, Y. Yao, M. H. Shao, J. Am. Chem. Soc. 2020, 142, 8748.

[7] B. Huang, R. R. Rao, S. You, K. Hpone Myint, Y. Song, Y. Wang, W. Ding, L. Giordano, Y. Zhang, T. Wang, S. Muy, Y. Katayama, J. C. Grossman, A. P. Willard, K. Xu, Y. Jiang, Y. Shao-Horn, JACS Au 2021, 1, 1674.

[8] X. Y. Tian, P. C. Zhao, W. C. Sheng, Adv. Mater. 2019, 31, 1808066.

[9] O. Y. Jung, M. N. Jackson, R. P. Bisbey, N. E. Kogan, Y. Surendranath, Joule 2022, 6, 476.

[10] J. Rossmeisl, K. Chan, R. Ahmed, V. Tripkovic, M. E. Björketun, Phys. Chem. Chem. Phys. 2013, 15, 10321.

[11] Y. Yang, C. R. Peltier, R. Zeng, R. Schimmenti, Q. H. Li, X. Huang, Z. F. Yan, G. Potsi, R. Selhorst, X. Y. Lu, W. X. Xu, M. Tader, A. Soudackov, H. G. Zhang, M. Krumov, E. Murray, P. T. Xu, J. Hitt, L. X. Xu, H. Y. Ko, B. G. Ernst, C. Bundschu, A. Luo, D. Markovich, M. X. Hu, C. He, H. S. Wang, J. Y. Fang, R. A. DiStasio, L. F. Kourkoutis, A. Singer, K. J. T. Noonan, L. Xiao, L. Zhuang, B. S. Pivovar, P. Zelenay, E. Herrero, J. M. Feliu, J. Suntivich, E. P. Giannelis, S. Hammes-Schiffer, T. Arias, M. Mavrikakis, T. E. Mallouk, J. D. Brock, D. A. Muller, F. J. DiSalvo, G. W. Coates, H. D. Abruña, Chem. Rev. 2022, 122, 6117.

[12] L. Giordano, B. H. Han, M. Risch, W. T. Hong, R. R. Rao, K. A. Stoerzinger, Y. Shao-Horn, Catal. Today 2016, 262, 2.

[13] C. Z. Yang, M. Batuk, Q. Jacquet, G. Rousse, W. Yin, L. T. Zhang, J. Hadermann, A. M. Abakumov, G. Cibin, A. Chadwick, J. M. Tarascon, A. Grimaud, ACS Energy Lett. 2018, 3, 2884.

[14] S. Nitopi, E. Bertheussen, S. B. Scott, X. Y. Liu, A. K. Engstfeld, S. Horch, B. Seger, I. E. L. Stephens, K. Chan, C. Hahn, J. K. Norskov, T. F. Jaramillo, I. Chorkendorff, Chem. Rev. 2019, 119, 7610.

[15] Y. Yoon, A. S. Hall, Y. Surendranath, Angew. Chem. Int. Ed. 2016, 55, 15282.

[16] B. Kim, S. Ma, H. R. M. Jhong, P. J. A. Kenis, Electrochim. Acta 2015, 166, 271.

[17] A. Goyal, G. Marcandalli, V. A. Mints, M. T. M. Koper, J. Am. Chem. Soc. 2020, 142, 4154.

[18] W. X. Wu, L. P. Xu, Q. Lu, J. P. Sun, Z. Y. Xu, C. S. Song, J. C. Yu, Y. Wang, Adv. Mater. 2025, 37, 2312894.

[19] R. Casebolt, K. W. Kimura, K. Levine, J. A. C. DaSilva, J. Kim, T. A. Dunbar, J. Suntivich, T. Hanrath, ChemElectroChem 2021, 8, 681.

[20] V. J. Ovalle, M. M. Waegele, J. Phys. Chem. C 2021, 125, 18567.

[21] E. R. Sauvé, B. Y. Tang, N. K. Razdan, W. L. Toh, S. P. Weng, Y. Surendranath, Joule 2024, 8, 728.

[22] W. Chen, M. K. Zhang, B. Y. Liu, J. Cai, Y. X. Chen, Curr. Opin. Electrochem. 2022, 34, 101003.

[23] B. M. Tackett, D. Raciti, N. W. Brady, N. L. Ritzert, T. P. Moffat, J. Phys. Chem. C 2022, 126, 7456.

[24] F. Zhang, A. C. Co, Angew. Chem. Int. Ed. 2020, 59, 1674.

[25] X. Liu, M. C. O. Monteiro, M. T. M. Koper, Phys. Chem. Chem. Phys. 2023, 25, 2897.

[26] A. Botz, J. Clausmeyer, D. Öhl, T. Tarnev, D. Franzen, T. Turek, W. Schuhmann, Angew. Chem. Int. Ed. 2018, 57, 12285.

[27] A. Bohme, J. C. Bui, A. Q. Fenwick, R. Bhide, C. N. Feltenberger, A. J. Welch, A. J. King, A. T. Bell, A. Z. Weber, S. Ardo, H. A. Atwater, Energy Environ. Sci. 2023, 16, 1783.

[28] B. Fuladpanjeh-Hojaghan, M. M. Elsutohy, V. Kabanov, B. Heyne, M. Trifkovic, E. P. L. Roberts, Angew. Chem. Int. Ed. 2019, 58, 16815.

[29] A. J. Welch, A. Q. Fenwick, A. Böhme, H. Y. Chen, I. Sullivan, X. Q. Li, J. S. DuChene, C. X. Xiang, H. A. Atwater, J. Phys. Chem. C 2021, 125, 20896.

[30] M. C. O. Monteiro, M. T. M. Koper, Curr. Opin. Electrochem. 2021, 25, 100649.

[31] O. Ayemoba, A. Cuesta, A. C. S. Appl, Mater. Interfaces 2017, 9, 27377.

[32] K. L. Yang, R. Kas, W. A. Smith, J. Am. Chem. Soc. 2019, 141, 15891.

[33] D. A. Henckel, M. J. Counihan, H. E. Holmes, X. Y. Chen, U. O. Nwabara, S. Verma, J. Rodríguez-López, P. J. A. Kenis, A. A. Gewirth, ACS Catal. 2021, 11, 255.

[34] Z. S. Zhang, L. Melo, R. P. Jansonius, F. Habibzadeh, E. R. Grant, C. P. Berlinguette, ACS Energy Lett. 2020, 5, 3101.

[35] X. Lu, C. Q. Zhu, Z. S. Wu, J. Xuan, J. S. Francisco, H. L. Wang, J. Am. Chem. Soc. 2020, 142, 15438.

[36] X. Yang, J. Nash, N. Oliveira, Y. S. Yan, B. Xu, Angew. Chem. Int. Ed. 2019, 58, 17718.

[37] H. Oschinski, S. D. Beinlich, K. Reuter, N. G. Hörmann, J. Electrochem. Soc. 2024, 171, 126501.

[38] J. Mateo, D. Tryk, C. Cabrera, Y. Ishikawa, Mol. Simul. 2008, 34, 1065.

[39] P. Kowalczyk, S. Savard, A. Lasia, J. Electroanal. Chem. 2004, 574, 41.

[40] B. Losiewicz, R. Jurczakowski, A. Lasia, Electrochim. Acta 2012, 80, 292.

[41] J. Z. Wu, Chem. Rev. 2022, 122, 10821.

[42] N. Garcia-Araez, V. Climent, E. Herrero, J. M. Feliu, J. Lipkowski, Electrochim. Acta 2006, 51, 3787.

[43] A. H. Shah, Z. S. Zhang, Z. H. Huang, S. B. Wang, G. Y. Zhong, C. Z. Wan, A. N. Alexandrova, Y. Huang, X. F. Duan, Nat. Catal. 2022, 5, 923.

[44] G. García, ChemElectroChem 2017, 4, 459.

[45] R. Subbaraman, D. Tripkovic, D. Strmcnik, K. C. Chang, M. Uchimura, A. P. Paulikas, V. Stamenkovic, N. M. Markovic, Science 2011, 334, 1256.

[46] M. T. M. Koper, Chem. Sci. 2013, 4, 2710.

[47] H. L. Tao, S. J. Wang, H. L. Liu, C. Lian, Angew. Chem. Int. Ed. 2025, 64, e202418447.

[48] C. Lian, M. Janssen, H. L. Liu, R. van Roij, Phys. Rev. Lett. 2020, 124, 76001.

[49] Y. T. Lin, C. Lian, M. U. Berrueta, H. L. Liu, R. van Roij, Phys. Rev. Lett. 2022, 128, 206001.

[50] Q. Sun, N. J. Oliveira, S. Kwon, S. Tyukhtenko, J. J. Guo, N. Myrthil, S. A. Lopez, I. Kendrick, S. Mukerjee, L. Ma, S. N. Ehrlich, J. K. Li, W. A. Goddard, Y. S. Yan, Q. Y. Jia, Nat. Energy 2023, 8, 859.

[51] W. G. Sun, Z. Xu, C. D. Qiao, B. X. Lv, L. G. Gai, X. X. Ji, H. H. Jiang, L. B. Liu, Adv. Sci. 2022, 9, 2201679.

[52] G. K. H. Wiberg, M. Arenz, Electrochim. Acta 2015, 158, 13.

[53] M. Chintapalli, K. Timachova, K. R. Olson, S. J. Mecham, D. Devaux, J. M. DeSimone, N. P. Balsara, Macromolecules 2016, 49, 3508.

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2025 The Author(s). Energy & Environmental Materials published by John Wiley & Sons Australia, Ltd on behalf of Zhengzhou University.