Carbon spheres with hierarchical micro/mesopores for water desalination by capacitive deionization

In this work, porous carbon spheres with hierarchical pores (denoted as hCSs) were fabricated via a sol-gel process using a surfactant-directing assembly strategy and investigated as capacitive deionization (CDI) electrode materials for the first time. By using transmission electron microscopy and N₂ adsorption/desorption analyses, a hierarchy of micropores and mesopores was demonstrated to be present in the hCSs. Based on the results of CDI measurements, the hCSs obtained at 800 °C (hCSs-800) displayed the best electrosorption performance of all the hCS samples tested: hCSs-800 exhibited a high electrosorption capacity of 15.8 mg g^-1 when the initial NaCl concentration was 500 mg L^-1. Furthermore, according to a Kim-Yoon plot analysis, hCSs-800 integrated the merits of both a high electrosorption capacity and fast electrosorption rate, indicating the superiority of these hCSs for CDI applications.