Surface Geometry Governs Cation Effects via Nonlocal Solvent Gating
Abstract
Catalyst structure and electrolyte composition are commonly regarded as independent descriptors governing electrocatalytic behavior. Here, we show that surface geometry governs cation effects through catalyst–electrolyte coupling that we term nonlocal solvent gating. Constant-potential ab initio molecular dynamics simulations and free-energy sampling reveal contrasting cation (Li+, K+, Cs+)-dependent CO2 reduction activity on single-crystal and polycrystalline Au. On relatively flat Au(100) and Au(111), cation hydration controls the contact-water structure, and the solvent penalty for CO2 approach decreases with increasing cation size. In Au(110) grooves, surface-registered water instead reverses the cation response. Remarkably, an Au(110)-like groove embedded within an otherwise flat Au(111) terrace induces the same reversed cation trend even at geometrically pristine terrace sites away from the groove, demonstrating that a local surface motif can regulate electrolyte effects nonlocally through the interfacial solvent. An additional calculation for Rb+ supports this mechanism, yielding an intermediate groove-induced cavity penalty. This nonlocal coupling provides a mechanistic basis for the experimentally observed volcano-shaped cation dependence on flame-annealed polycrystalline Au, which cannot be explained by independent single-facet responses. These results establish interfacial water as a medium through which surface geometry and electrolyte composition become intrinsically coupled, extending conventional local-site descriptions of complex electrocatalytic interfaces to include nonlocal solvent-mediated effects.
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BibTeX
@misc{ma2026surface,
title = {{Surface Geometry Governs Cation Effects via Nonlocal Solvent Gating}},
author = {Xiao Ma and Leshen Zhang and Guangsheng Liu and Abdulrahman Allangawi and Huabin Zhang and Wan-Lu Li},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008697/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008697/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Surface Geometry Governs Cation Effects via Nonlocal Solvent Gating
AU - Xiao Ma
AU - Leshen Zhang
AU - Guangsheng Liu
AU - Abdulrahman Allangawi
AU - Huabin Zhang
AU - Wan-Lu Li
PY - 2026
DA - 2026/09/11
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008697/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008697/v1
AB - Catalyst structure and electrolyte composition are commonly regarded as independent descriptors governing electrocatalytic behavior. Here, we show that surface geometry governs cation effects through catalyst–electrolyte coupling that we term nonlocal solvent gating. Constant-potential ab initio molecular dynamics simulations and free-energy sampling reveal contrasting cation (Li+, K+, Cs+)-dependent CO2 reduction activity on single-crystal and polycrystalline Au. On relatively flat Au(100) and Au(111), cation hydration controls the contact-water structure, and the solvent penalty for CO2 approach decreases with increasing cation size. In Au(110) grooves, surface-registered water instead reverses the cation response. Remarkably, an Au(110)-like groove embedded within an otherwise flat Au(111) terrace induces the same reversed cation trend even at geometrically pristine terrace sites away from the groove, demonstrating that a local surface motif can regulate electrolyte effects nonlocally through the interfacial solvent. An additional calculation for Rb+ supports this mechanism, yielding an intermediate groove-induced cavity penalty. This nonlocal coupling provides a mechanistic basis for the experimentally observed volcano-shaped cation dependence on flame-annealed polycrystalline Au, which cannot be explained by independent single-facet responses. These results establish interfacial water as a medium through which surface geometry and electrolyte composition become intrinsically coupled, extending conventional local-site descriptions of complex electrocatalytic interfaces to include nonlocal solvent-mediated effects.
ER -