Theoretical Assessment of the Interaction Mechanism Between Hydrofluoroolefins and Metal Electrodes in the Presence of Discharge

Hydrofluoroolefins (HFOs) such as HFO-1234ze(E) and HFO-1336mzz(E) are potential alternatives to SF 6 due to their promising dielectric strength and low global warming potential. However, the interaction mechanism between HFOs and metal surfaces is not yet clear in discharged conditions. In this study, a density functional theory calculation is conducted to investigate the adsorption behavior of HFOs over metallic electrodes in the presence of electric field and surface charges. The molecular structures of HFOs hold stable over Cu and Al surfaces when a electric field (<0.5 V/Å) and 1.0 |e| charge are applied, and they undergo dissociative adsorption over the Al (111) surface at combined 0.5 V/Å↓ + 1.0 |e| case. By contrast, over the passivated α-Al 2 O 3 (0001) surface of Al electrodes, the excess charge significantly promotes the adsorption of HFOs, resulting in a strong surface bonding and even a self-decomposition. Charge analysis indicates that the excess electrons facilitate the interaction of HFOs with α-Al 2 O 3 slab via the enhancement of charge transfer and orbital hybridization. In this regard, the Cu electrode could be more applicable for the long-run HFO-insulation devices due to their inert reaction performance in discharged conditions. This study provides insights into the assessment of HFOs behavior over metal electrodes in the presence of discharge effects.