Modulating the surfaces functional groups and defects in carbon via salt template method for high-performance capacitor deionization

Conventional carbon-based materials have been widely applied for capacitive deionization (CDI) because of their excellent electrical conductivity and specific surface area. The surface functional group and defect of carbon materials have a critical impact on CDI performance. Hence, a hierarchical mesoporous/macropores carbon (MPC) with abundant quinone functional groups (C = O) and defects were synthesized by a salt template method. The introduction of C = O functional groups and defects not only effectively shortens the ions transport path, but also enhances the pseudocapacitive behavior of carbon materials. As a result, the MPC represents a fantastic desalting capacity of 31.3 mg g-1 for sodium salt (500 mg L-1 NaCl) at an applied voltage of 1.2 V. Meanwhile, the MPC also shows superior salt adsorption rate and great cycling performance. In addition, the desalination mechanism was analyzed in detail by systematic ex-situ measurements. Here, this work presents a novel perspective for designing high-performance carbon-based CDI electrode materials.