Recently, a research team led by Professor ChongyiLing, Professor JinlanWang, and Associate Professor Qiang Li from the School of Physics at Southeast University made significant progress in the field of the dynamic evolution mechanism of catalysts. The related research findings, titled “Revisiting Catalyst Restructuring in CO2 Reduction: The Dominant Yet Overlooked Role of Hydrogen,” have been published in the Journal of the American Chemical Society (JACS), a top international chemistry journal.
Copper (Cu) is currently the only known single-metal catalyst capable of efficiently converting carbon dioxide into high-value-added multicarbon (C2+) products. Its excellent performance is closely related to the dynamic surface restructuring that occurs under reaction conditions. However, the fundamental driving force behind this structural evolution has long been a subject of controversy. The mainstream view suggests that surface restructuring is primarily induced by the adsorption of reaction intermediates, particularly carbon monoxide (*CO). However, this explanation does not fully align with experimental results: within the potential range where significant restructuring is experimentally observed, the surface coverage of *CO is typically less than 5%, and its weak adsorption makes it difficult to overcome the high energy barrier required for copper dissolution.
To address this challenge, the research team conducted systematic theoretical simulations and shifted their focus to adsorbed hydrogen (*H). This key species is ubiquitous in aqueous electrochemical environments but has long been overlooked due to its overlapping spectroscopic signals with *CO. Combining first-principles density functional theory (DFT) calculations based on an explicit solvent model with ab initio molecular dynamics (AIMD) simulations, the team proposed a unified “H-Activated Restructuring Mechanism” for the first time. This mechanism explicitly identifies adsorbed hydrogen as the dominant factor driving the dynamic restructuring of the catalyst, thereby establishing a new theoretical framework for understanding these processes.
The study reveals that adsorbed hydrogen can enhance anti-bonding orbital interactions through electron injection and induce significant lattice expansion. This drives the metal surface into a preactivated loosened state, which substantially lowers the kinetic energy barrier for atom leaching. As the electrochemical potential shifts, the dynamic structural transformation of the catalyst evolves through three distinct regimes. At low overpotentials, surfaceadsorbed hydrogen (*Hsurf) initiates localized lattice distortion.As the coverage of CO2 reduction intermediates (*R) increases, the preloosening effect of *H and the “pulling” effect of the intermediates work synergisticallyduring intermediate overpotentials. This prompts a large number of metal atoms to leach and re-aggregate, forming highly active, low-coordination clusters.Hydrogen further penetrates the subsurface (*Hsub). The internal pressure generated by subsurface hydrogen, combined with the external pulling force of surface intermediates, creates a "push-pull" effect that drives deeper structural transformationsat higher negative potentials.The continuous “dissolution-redeposition” cycle constantly generates new defect sites. These sites have been proven to significantly lower the energy barrier for C–C coupling (for instance, the C–C coupling barrier can be reduced to 0.43 eV), serving as the true high-activity reaction sites.
Furthermore, the research team extended this mechanism to various other metal systems, including Au, Ag, Pt, Ni, and Ir. They established a universal thermodynamic descriptor, the average adatom formation energy, which elegantly unifies and predicts the stability trends of various metal catalysts in complex electrochemical environments. The predictions demonstrate high consistency with experimental observations. The study also found that by introducing metals with a higher hydrogen penetration energy barrier (such as Ir) for surface alloying, the further penetration of hydrogen into the subsurface can be effectively suppressed, thereby significantly enhancing the long-term structural stability of the catalyst. This work provides a fresh theoretical foundation and innovative design strategies for developing electrocatalytic materials that possess both high activity and high stability.
The first author of this paper is HaonaZhang, a PhD student at Southeast University. Professor Chongyi Ling, Professor Jinlan Wang, and Associate Professor Qiang Li from the School of Physics at Southeast University are the co-corresponding authors. This work was supported by the National Natural Science Foundation of China (Excellent Young Scientists Fund and Youth Fund, etc.).
Paper Link: https://doi.org/10.1021/jacs.6c05573
