Extended Data Fig. 3: The wettability and morphology of the DPF in the redox process.
From: Continuous air purification by aqueous interface filtration and absorption
a. The self-designed setup for in situ monitoring the contact angle of a dichloromethane droplet on the DPF during adjusting the electrochemical potentials underwater. A three-electrode system was used to control the electrochemical potential. DPF was served as the working electrode. Ag/AgCl electrode and a platinum plate were used as the reference electrode and the counter electrode, respectively. 0.1 M LiClO4 aqueous solution was used as the electrolyte. b. Reversible wettability switching of the functional liquid on DPF during the continuous cycle redox process. To obtain a wide range of wettability values with a small potential difference, we selected +0.40 V and −0.60 V as the optimal working oxidation and reduction potentials, respectively, based on the contact angle analysis at different potentials in Fig. 2b. Error bars represent the standard deviation from five independent measurements. c. Underwater wettability switching of oil on DPF during the cycle redox process. Error bars represent the standard deviation from five independent measurements. d, e. Analysis of the adhesion work between the functional liquid and the matrix in reduction state (d) and oxidation state (e): the polar part of the surface tension/energy and the corresponding surface tension/energy can be identified and the combination of them provides the optimum adhesion between DPF and functional liquid. The blue and red straight line represents the optimum adhesive force, and a range of acceptable performance can be proposed. From the results, one can conclude that the functional liquid falls in the optimum zone in the reduction state, which indicates that the affinity between the functional liquid and the matrix adheres well. f, g. 3D atomic force microscope (AFM) images show height variations on the surface of the matrix in reduction state (f) and oxidation state (g). AFM results suggest that the surface of the matrix changes from smooth to rough during the reduction process due to the influx of lithium ions49, which could also increase the hydrophilicity of the surface.
