Electron beam-based fabrication of crosslinked hydrophilic carbon electrodes and their application for capacitive deionization

Abstract

In this research, we demonstrated that a crosslinked hydrophilic carbon electrode with better electrochemical performance than hydrophobic counterparts can easily be produced using room-temperature, quick electron-beam irradiation with a hydrophilic methacryloyl-substituted polyvinyl alcohol (SPVA) binder. The SPVA binder was effectively synthesized by trans-esterification of PVA with glycidyl methacrylate. The hydrophilic carbon electrode cast on a graphite sheet from a slurry of activated carbon (AC) and SPVA was irradiated with an electron beam to form a crosslinked structure. The analytical results in terms of the morphology, solvent resistance, chemical composition, and contact angle revealed that the carbon electrode was completely crosslinked by electron-beam irradiation even at the dose of 100 kGy (irradiation time = 180 s). The new electrode exhibited superior water-wettability due to the hydrophilic functionality of SPVA. Furthermore, the hydrophilic carbon electrode with an AC : SPVA composition of 90 : 10 and an absorbed dose of 200 kGy, exhibited a specific capacitance of 127 F g⁻¹ (67% higher than the hydrophobic poly(vinylidene fluoride) (PVDF)-based counterpart with the same composition). The specific capacitance was further improved to 160 F g⁻¹ with an increase in the AC content. The hydrophilic carbon electrode exhibited noticeably better desalination efficiency than the hydrophobic PVDF-based counterpart.