Repulsive Gas-Electrode van der Waals Forces Enable Charge Transfer Reactions under Chemically Modified Bubbles.

Gas bubbles are ideal hydrophobic structures that underpin technologies ranging from mineral processing to chemical analysis. The technological value of bubbles lies in their ability to create hydrophobic-hydrophilic phase boundaries, simply and efficiently. However, bubbles remain largely incompatible with electrochemical processes: they block charge transfer reactions by interrupting solution-electrode contact. We demonstrate a path to integrate bubbles with electrode reactions. For micrometer-sized electrodes and surface-active reactants (<60 mN/m), a nanoscale disjoining liquid film forms under bubbles that visually appear as surface-adherent. Gas-solution-electrode junctions sustained by repulsive van der Waals (vdW) forces allow the oil-like properties of bubbles to be harnessed in aqueous electrolytes. Through vdW-stabilized junctions, bubbles are redefined from detrimental dielectric blocks to facilitators of electrode processes. This is demonstrated by 10-fold rate enhancements, improved reaction reversibility and ionic conductivity, and the redox cycling of enzymes stabilized by confinement between bubbles and electrodes.