Fig. 2
From: In situ reversible underwater superwetting transition by electrochemical atomic alternation
The binary composite surface governs the in situ reversible superwetting transition. a Cyclic voltammetry of a Cu electrode in H2SO4/SnSO4 (red line) and H2SO4 electrolyte (black line). Scan rate: 20 mV s−1. b The electrochemical quartz crystal microbalance evaluation of the gravimetric alteration during this in situ reversible superwetting transition. c The in situ Raman spectrum characterization of hydrogen bonding on the electrode surface when the potential was switched on and off. Peaks A and B are assignable to the intermolecular symmetric and antisymmetric stretching vibrations of the hydrogen bond O-D, respectively; peak C is the bending vibration of the D-O-D bond; and peak D is related to the symmetric stretching vibration of the S-O bond. d The schematics show that the Cu/Sn binary composite surface enables drastic altering of the hydrogen-bonding network at the electrolyte/electrode interface, making the oil droplet experience the in situ reversible transition between superphobicity and superphilicity. When the potential is on, the enrichment of Sn atoms inhibits the hydrogen-bonding network on the electrode surface, turning the electrode into the underwater superoleophilic state; when the potential is off, the Cu presents a high affinity to the hydroxyl group, leading the surface to return to its intrinsic superphobic state
