The origin of the large kinetic pH effect in hydrogen electrocatalysis, that is, the approximately two orders of magnitude decrease in reaction kinetics when moving from acid to alkaline, remains far from having a consensus. Here we show that it is the significantly different connectivity of hydrogen-bond networks in electric double layers that causes the large kinetic pH effect. This result has been obtained by meticulously comparing the electric double layers of acid and alkaline interfaces from ab initio molecular dynamics simulations, and the computed vibrational density of states of water molecules in the interfaces simulated with ab initio molecular dynamics, with the results of in situ surface-enhanced infrared absorption spectroscopy. Using a Pt–Ru alloy as a model catalyst, we further reveal an unanticipated role of OH adsorption in improving the kinetics of alkaline hydrogen electrocatalysis, namely, by increasing the connectivity of hydrogen-bond networks in electric double layers rather than by merely affecting the energetics of surface reaction steps. These findings highlight the key roles of electric double layer structures in electrocatalysis.
This is a preview of subscription content, access via your institution
Subscribe to Nature+
Get immediate online access to Nature and 55 other Nature journal
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Representative data and extended datasets that support the findings reported in this study are available in the manuscript and the Supplementary Information. The data in the figures shown in the main text and the atomic coordinates of the initial and final configurations of the trajectories in the AIMD simulations are provided as supplementary files. Additional data are available from the corresponding author upon reasonable request.
Chow, J., Kopp, R. J. & Portney, P. R. Energy resources and global development. Science 302, 1528–1531 (2003).
Turner, J. A. Sustainable hydrogen production. Science 305, 972–974 (2014).
Inzelt, G. Milestones of the development of kinetics of electrode reactions. J. Solid State Electrochem. 15, 1373–1389 (2011).
Huang, J., Li, P. & Chen, S. Quantitative understanding of the sluggish kinetics of hydrogen reactions in alkaline media based on a microscopic Hamiltonian model for the Volmer step. J. Phys. Chem. C 123, 17325–17334 (2019).
Sheng, W., Gasteiger, H. A. & Shao-Horn, Y. Hydrogen oxidation and evolution reaction kinetics on platinum: acid vs alkaline electrolytes. J. Electrochem. Soc. 157, B1529–B1536 (2010).
Subbaraman, R. et al. Enhancing hydrogen evolution activity in water splitting by tailoring Li+-Ni(OH)2-Pt interfaces. Science 334, 1256–1260 (2011).
Durst, J. et al. New insights into the electrochemical hydrogen oxidation and evolution reaction mechanism. Energy Environ. Sci. 7, 2255–2260 (2014).
Zheng, Y., Jiao, Y., Vasileff, A. & Qiao, S. Z. The hydrogen evolution reaction in alkaline solution: from theory, single crystal models, to practical electrocatalysts. Angew. Chem. Int. Ed. 57, 7568–7579 (2018).
Strmcnik, D., Lopes, P. P., Genorio, B., Stamenkovic, V. R. & Markovic, N. M. Design principles for hydrogen evolution reaction catalyst materials. Nano Energy 29, 29–36 (2016).
Sheng, W. et al. Correlating hydrogen oxidation and evolution activity on platinum at different pH with measured hydrogen binding energy. Nat. Commun. 6, 5848 (2015).
Zheng, J., Sheng, W., Zhuang, Z., Xu, B. & Yan, Y. Universal dependence of hydrogen oxidation and evolution reaction activity of platinum-group metals on pH and hydrogen binding energy. Sci. Adv. 2, e1501602 (2016).
Giles, S. A. et al. Recent advances in understanding the pH dependence of the hydrogen oxidation and evolution reactions. J. Catal. 367, 328–331 (2018).
Zheng, J., Nash, J., Xu, B. & Yan, Y. Perspective—towards establishing apparent hydrogen binding energy as the descriptor for hydrogen oxidation/evolution reactions. J. Electrochem. Soc. 165, H27 (2018).
Cheng, T., Wang, L., Merinov, B. V. & Goddard, W. A. III Explanation of dramatic pH-dependence of hydrogen binding on noble metal electrode: greatly weakened water adsorption at high pH. J. Am. Chem. Soc. 140, 7787–7790 (2018).
Chen, X., McCrum, I. T., Schwarz, K. A., Janik, M. J. & Koper, M. T. Co‐adsorption of cations as the cause of the apparent pH dependence of hydrogen adsorption on a stepped platinum single‐crystal electrode. Angew. Chem. Int. Ed. 56, 15025–15029 (2017).
Janik, M. J., McCrum, I. T. & Koper, M. T. On the presence of surface bound hydroxyl species on polycrystalline Pt electrodes in the “hydrogen potential region” (0-0.4 V-RHE). J. Catal. 367, 332–337 (2018).
Ledezma-Yanez, I. et al. Interfacial water reorganization as a pH-dependent descriptor of the hydrogen evolution rate on platinum electrodes. Nat. Energy 2, 17031 (2017).
Zhu, S., Qin, X., Yao, Y. & Shao, M. pH-dependent hydrogen and water binding energies on platinum surfaces as directly probed through surface-enhanced infrared absorption spectroscopy. J. Am. Chem. Soc. 142, 8748–8754 (2020).
Wang, Y. H. et al. Spectroscopic verification of adsorbed hydroxy intermediates in the bifunctional mechanism of the hydrogen oxidation reaction. Angew. Chem. Int. Ed. 133, 5772–5775 (2021).
Strmcnik, D. et al. Improving the hydrogen oxidation reaction rate by promotion of hydroxyl adsorption. Nat. Chem. 5, 300–306 (2013).
Danilovic, N. et al. Enhancing the alkaline hydrogen evolution reaction activity through the bifunctionality of Ni(OH)2/metal catalysts. Angew. Chem. Int. Ed. 124, 12663–12666 (2012).
Subbaraman, R. et al. Trends in activity for the water electrolyser reactions on 3d M (Ni, Co, Fe, Mn) hydr(oxy)oxide catalysts. Nat. Mater. 11, 550–557 (2012).
Dinh, C. T. et al. Multi-site electrocatalysts for hydrogen evolution in neutral media by destabilization of water molecules. Nat. Energy 4, 107–114 (2019).
Men, Y., Li, P., Zhou, J., Chen, S. & Luo, W. Trends in alkaline hydrogen evolution activity on cobalt phosphide electrocatalysts doped with transition metals. Cell Rep. Phys. Sci. 1, 100136 (2020).
Wang, Y. et al. Pt–Ru catalyzed hydrogen oxidation in alkaline media: oxophilic effect or electronic effect? Energy Environ. Sci. 8, 177–181 (2015).
Intikhab, S., Snyder, J. D. & Tang, M. H. Adsorbed hydroxide does not participate in the Volmer step of alkaline hydrogen electrocatalysis. ACS Catal. 7, 8314–8319 (2017).
McCrum, I. T. & Koper, M. T. The role of adsorbed hydroxide in hydrogen evolution reaction kinetics on modified platinum. Nat. Energy 5, 891–899 (2020).
Li, J. et al. Experimental proof of the bifunctional mechanism for the hydrogen oxidation in alkaline media. Angew. Chem. Int. Ed. 56, 15594–15598 (2017).
Rebollar, L. et al. “Beyond adsorption” descriptors in hydrogen electrocatalysis. ACS Catal. 10, 14747–14762 (2020).
Ramaswamy, N. et al. Hydrogen oxidation reaction in alkaline media: relationship between electrocatalysis and electrochemical double-layer structure. Nano Energy 41, 765–771 (2017).
Shen, L. F. et al. Interfacial structure of water as a new descriptor of the hydrogen evolution reaction. Angew. Chem. Int. Ed. 132, 22583–22588 (2020).
Serva, A., Salanne, M., Havenith, M. & Pezzotti, S. Size dependence of hydrophobic hydration at electrified gold/water interfaces. Proc. Natl Acad. Sci. USA 118, e2023867118 (2021).
Serva, A., Havenith, M. & Pezzotti, S. The role of hydrophobic hydration in the free energy of chemical reactions at the gold/water interface: size and position effects. J. Chem. Phys. 155, 204706 (2021).
Rosen, B. A. et al. Ionic liquid-mediated selective conversion of CO2 to CO at low overpotentials. Science 334, 643–644 (2011).
Hpone Myint, K., Ding, W. & Willard, A. P. The influence of spectator cations on solvent reorganization energy is a short-range effect. J. Phys. Chem. B 125, 1429–1438 (2021).
Wang, T. et al. Enhancing oxygen reduction electrocatalysis by tuning interfacial hydrogen bonds. Nat. Catal. 4, 753–762 (2021).
Berg, N., Bergwinkl, S., Nuernberger, P., Horinek, D. & Gschwind, R. M. Extended hydrogen bond networks for effective proton-coupled electron transfer (PCET) reactions: the unexpected role of thiophenol and its acidic channel in photocatalytic hydroamidations. J. Am. Chem. Soc. 143, 724–735 (2021).
Lan, Y. Q. et al. Implanting numerous hydrogen‐bonding networks in Cu‐porphyrin based nanosheet to boost CH4 selectivity in neutral media CO2 electroreduction. Angew. Chem. Int. Ed. 60, 2–9 (2021).
Alfarano, S. R. et al. Stripping away ion hydration shells in electrical double-layer formation: water networks matter. Proc. Natl Acad. Sci. USA 118, e2108568118 (2021).
Serva, A., Scalfi, L., Rotenberg, B. & Salanne, M. Effect of the metallicity on the capacitance of gold–aqueous sodium chloride interfaces. J. Chem. Phys. 155, 044703 (2021).
Le, J. B., Fan, Q. Y., Li, J. Q. & Cheng, J. Molecular origin of negative component of Helmholtz capacitance at electrified Pt(111)/water interface. Sci. Adv. 6, eabb1219 (2020).
Limmer, D. T., Willard, A. P., Madden, P. & Chandler, D. Hydration of metal surfaces can be dynamically heterogeneous and hydrophobic. Proc. Natl Acad. Sci. USA 110, 4200–4205 (2013).
Liu, Y., Kawaguchi, T., Pierce, M. S., Komanicky, V. & You, H. Layering and ordering in electrochemical double layers. J. Phys. Chem. Lett. 9, 1265–1271 (2018).
Strmcnik, D. et al. Effects of Li+, K+, and Ba2+ cations on the ORR at model and high surface area Pt and Au surfaces in alkaline solutions. J. Phys. Chem. Lett. 2, 2733–2736 (2011).
Grosjean, B., Bocquet, M. L. & Vuilleumier, R. Versatile electrification of two-dimensional nanomaterials in water. Nat. Commun. 10, 1656 (2019).
Dubouis, N. et al. The fate of water at the electrochemical interfaces: electrochemical behavior of free water versus coordinating water. J. Phys. Chem. Lett. 9, 6683–6688 (2018).
Dunwell, M., Yan, Y. & Xu, B. A surface-enhanced infrared absorption spectroscopic study of pH dependent water adsorption on Au. Surf. Sci. 650, 51–56 (2016).
Yamakata, A. & Osawa, M. Dynamics of double-layer restructuring on a platinum electrode covered by CO: laser-induced potential transient measurement. J. Phys. Chem. C 112, 11427–11432 (2008).
Osawa, M., Tsushima, M., Mogami, H., Samjeske, G. & Yamakata, A. Structure of water at the electrified platinum−water interface: a study by surface-enhanced infrared absorption spectroscopy. J. Phys. Chem. C 112, 4248–4256 (2008).
Zhu, S. et al. The role of ruthenium in improving the kinetics of hydrogen oxidation and evolution reactions of platinum. Nat. Catal. 4, 711–718 (2021).
Huang, B. et al. Cation- and pH-dependent hydrogen evolution and oxidation reaction kinetics. JACS Au 1, 1674–1687 (2021).
Tong, Y., Lapointe, F., Thämer, M., Wolf, M. & Campen, R. K. Hydrophobic water probed experimentally at the gold electrode/aqueous interface. Angew. Chem. Int. Ed. 56, 4211–4214 (2017).
Lambert, D. K. Vibrational Stark effect of adsorbates at electrochemical interfaces. Electrochim. Acta 41, 623–630 (1996).
Liu, E. et al. Unifying the hydrogen evolution and oxidation reactions kinetics in base by identifying the catalytic roles of hydroxyl-water-cation adducts. J. Am. Chem. Soc. 141, 3232–3239 (2019).
Jia, Q., Liu, E., Jiao, L., Li, J. & Mukerjee, S. Current understandings of the sluggish kinetics of the hydrogen evolution and oxidation reactions in base. Curr. Opin. Electrochem. 12, 209–217 (2018).
Strmcnik, D. et al. The role of non-covalent interactions in electrocatalytic fuel-cell reactions on platinum. Nat. Chem. 1, 466–472 (2009).
Intikhab, S. et al. Caffeinated interfaces enhance alkaline hydrogen electrocatalysis. ACS Catal. 10, 6798–6802 (2020).
Kresse, G. & Hafner, J. Ab initio molecular dynamics for liquid metals. Phys. Rev. B 47, 558–561 (1993).
Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).
Perdew, J. P. et al. Atoms, molecules, solids, and surfaces: applications of the generalized gradient approximation for exchange and correlation. Phys. Rev. B 46, 6671–6687 (1992).
Grimme, S., Antony, J., Ehrlich, S. & Krieg, H. A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 132, 154104 (2010).
Plimpton, S. Fast parallel algorithms for short-range molecular dynamics. J. Comput. Phys. 117, 1–19 (1995).
Aktulga, H. M., Fogarty, J. C., Pandit, S. A. & Grama, A. Y. Parallel reactive molecular dynamics: numerical methods and algorithmic techniques. Parallel Comput. 38, 245–259 (2012).
Shin, Y. K., Gai, L., Raman, S. & Van Duin, A. C. Development of a ReaxFF reactive force field for the Pt–Ni alloy catalyst. J. Phys. Chem. A 120, 8044–8055 (2016).
Mathew, K., Kolluru, V. C., Mula, S., Steinmann, S. N. & Hennig, R. G. Implicit self-consistent electrolyte model in plane-wave density-functional theory. J. Chem. Phys. 151, 234101 (2019).
Trasatti, S. The absolute electrode potential: an explanatory note (recommendations 1986). Pure Appl. Chem. 58, 955–966 (1986).
Li, P., Huang, J., Hu, Y. & Chen, S. Establishment of the potential of zero charge of metals in aqueous solutions: different faces of water revealed by ab initio molecular dynamics simulations. J. Phys. Chem. C 125, 3972–3979 (2021).
Li, P., Liu, Y. & Chen, S. Microscopic EDL structures and charge–potential relation on stepped platinum surface: insights from the ab initio molecular dynamics simulations. J. Chem. Phys. 156, 104701 (2022).
Le, J., Iannuzzi, M., Cuesta, A. & Cheng, J. Determining potentials of zero charge of metal electrodes versus the standard hydrogen electrode from density-functional-theory-based molecular dynamics. Phys. Rev. Lett. 119, 016801 (2017).
Marković, N. M., Grgur, B. N. & Ross, P. N. Temperature-dependent hydrogen electrochemistry on platinum low-index single-crystal surfaces in acid solutions. J. Phys. Chem. B 101, 5405–5413 (1997).
Oberhofer, H., Dellago, C. & Geissler, P. L. Biased sampling of nonequilibrium trajectories: can fast switching simulations outperform conventional free energy calculation methods? J. Phys. Chem. B 109, 6902–6915 (2005).
Chan, K. & Nørskov, J. K. Electrochemical barriers made simple. J. Phys. Chem. Lett. 6, 2663–2668 (2015).
Chan, K. & Nørskov, J. K. Potential dependence of electrochemical barriers from ab initio calculations. J. Phys. Chem. Lett. 7, 1686–1690 (2016).
Yan, Y. G. et al. Ubiquitous strategy for probing ATR surface-enhanced infrared absorption at platinum group metal-electrolyte interfaces. J. Phys. Chem. B 109, 7900–7906 (2005).
Liu, E. et al. Interfacial water shuffling the intermediates of hydrogen oxidation and evolution reactions in aqueous media. Energy Environ. Sci. 13, 3064–3074 (2020).
We gratefully acknowledge the financial support from the National Natural Science Foundation of China (grant nos 21832004 and 21673163 to S.C.) and C.-L. Guo at Wuhan University for fruitful discussions and kindly sharing the infrared spectrometer. We also gratefully acknowledge generous grants of computational resources from the Supercomputing Center of Wuhan University.
The authors declare no competing interests.
Peer review information
Nature Catalysis thanks Qingying Jia, Jun Cheng and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Figs. 1–33 and Notes 1–3.
Atomic coordinates of the initial and final configurations of the trajectories in AIMD simulations for the systems shown in Fig. 1 and Fig. 5 (in Vienna Ab initio Simulation Package CONTCAR format).
Data shown in Figs. 1–5.
About this article
Cite this article
Li, P., Jiang, Y., Hu, Y. et al. Hydrogen bond network connectivity in the electric double layer dominates the kinetic pH effect in hydrogen electrocatalysis on Pt. Nat Catal 5, 900–911 (2022). https://doi.org/10.1038/s41929-022-00846-8