Regulating Surface Wettability and Charge Density of Porous Carbon Particles by in Situ Growth of Polyaniline for Constructing an Efficient Electrical Percolation Network in Flow-Electrode Capacitive Deionization

Both electrical conductivity and surface wettability are required for the selection of active carbon materials in flow-electrode capacitive deionization, while a trade-off exists between these two properties. In this work, a hybrid material with a thin layer of polyaniline (PANI) coating on activated carbon (AC/PANI) was successfully developed to retain excellent electrical conductivity and acquire good surface wettability. By adjusting the dosage of initiator, AC/PANI composites with different loading fractions of PANI were obtained. The electrochemical testing demonstrated that the AC/PANI composites have higher specific capacitance and lower ion diffusion resistance compared to pure AC, resulting in better desalinization performance. Specifically, with a feed concentration of 1600 mg/L, excellent adsorption capacity and high charge efficiency can be simultaneously achieved at 13.51 mg/g and 92.21%, respectively. Benefiting from the formation of a continuous electrical percolation network and reduced solid/liquid interfacial transport resistance, a 39% enhancement of average salt adsorption rate (from 0.54 to 0.75 μmol/min/cm2) was obtained.