Fluctuation-Driven Chemistry at Aqueous Interfaces and Beyond

Interfacial electric fields at gas-water, oil-water, and solid-water boundaries are frequently invoked to explain radical formation under ambient conditions. Field strengths of 10⁷-10⁹ V m^-1 are often cited as sufficient for this purpose. However, the electrostatic work accessible from such fields over molecular distances is substantially smaller than the energies associated with direct one-electron detachment or ionization. This discrepancy raises the question of whether interfacial electric fields directly drive chemistry or modulate an intrinsic property of liquid water. Here we argue that equilibrium interfacial electric fields bias molecular orientation and reaction kinetics but do not constitute a primary energetic input for bond-breaking chemistry. Instead, we propose a fluctuation-driven model in which transient, partially charge-separated configurations of the hydrogen-bond network emerge from cooperative hydrogen-bond fluctuations and can be kinetically selected by solutes (e.g., H⁺, CO₂, formate, DMPO, crown ethers) or catalytic surfaces through electronic coupling, generating charge-transfer pathways involving configurations such as S^…(H₂O)_n ^-δ or S^…(H₂O)_n ^+δ, which yield measurable radical products. Interfaces, ions, and weak perturbations reshape the free-energy landscape and alter fluctuation statistics; water autoionization and radical formation can therefore be viewed within a common statistical framework based on fluctuation-accessible electronic configurations.