Porous carbon hollow spheres synthesized via a modified Stöber method for capacitive deionization

Abstract

Capacitive deionization (CDI) is a promising desalination technology that is environmentally friendly and requires far less energy when compared with conventional technologies such as reverse osmosis. One of the main strategies used to improve the desalination performance is to synthesize materials that are electrically conductive, have high surface areas and are chemically stable. In this work, porous carbon hollow spheres of various sizes were synthesized using a modified Stöber process. The morphology, porosity and electrochemical properties of the spheres are studied using SEM, TEM, BET and CV techniques while their desalination performances are evaluated based on batch-mode CDI experiments. Based on our results, it is found that spheres of smaller sizes exhibit larger specific surface areas, higher specific capacitances and electrosorption capacities. The largest surface area of 809.91 m² g⁻¹ was obtained for a carbon hollow sphere of approximately 230 nm and a salt removal capacity of up to 18.88 mg g⁻¹ was observed. Besides that, the electrosorption isotherms and kinetics were studied and reported.