Probing voltage-induced chemical reactions and anharmonicity with a confined vacuum light field

In this work, we present a proof-of-concept investigation of non-equilibrium chemical reaction dynamics at a molecule-electrode interface, driven out of equilibrium by an applied voltage bias and mediated by a confined, enhanced vacuum electromagnetic field inside an optical cavity. The coupled electron-vibration-photon system, together with the electrodes and a dissipative environment, is described within an open quantum system framework and solved using a numerically exact quantum dynamical approach. The reaction coordinate is modeled using a Morse potential, enabling explicit treatment of molecular anharmonicity and bond-breaking behavior. By varying the cavity frequency across the infrared regime to cover typical nuclear vibrational energies, we observe multiple resonant rate suppression features that emerge whenever the cavity mode is brought into resonance with a dipole-allowed vibrational transition along the anharmonic ladder up to the dissociation threshold. These findings open the door to extending polaritonic chemistry into genuinely non-equilibrium scenarios relevant to molecule-electrode interfaces. Moreover, building on these results, we further propose a multi-mode vibrational strong coupling strategy in which several cavity modes are individually matched to distinct vibrational transitions. This engineered multi-resonant cavity induces a stepwise vibrational ladder descending process that efficiently drains vibrational excited energy. The resulting cavity-assisted cooling suggests a potential route toward mitigating voltage-induced bond rupture and the long-standing instability issues of molecular junctions operating under high bias.