Mesopore-dominated Porous Carbon Derived from Confinement-Region Activation Strategy Toward High Capacitive Desalination Performance

Traditional activated carbon derived from KOH activation method has been used as capacitive deionization electrode. Unfortunately, activated carbon dominated by microporous structures has a poor hydrophilicity and inferior conductivity, which has a serious impact on the desalination capacity. Herein, a novel reduced graphene oxide/porous carbon composite are rational synthesized by compressing KOH, graphene oxide and asphalt into cubic embryo with optimum tableting pressure (10 MPa) and followed by a confinement-region activation strategy. As capacitive deionization material, the reduced graphene oxide/porous carbon has high specific surface areas, abundant mesoporous volume, good hydrophilicity and high conductivity, and resulting in a large desalination capacity (25.1 mg g-1), outstanding linearity (R2 = 0.914) between the desalination capacity and mesopore volume, high maximum salt adsorption rate (0.117 mg g-1 s-1), superior charge efficiency (73.8%) and a long-term cycling stability for 200 cycles (84.9% desalination capacity retention). Furthermore, various density functional theory models of carbon material with different pore sizes (0-12 & ANGS;) are rational fabricated to expound the effect of pore size on saline ions adsorption capacity, and showing a large the pore size is, a better the ion adsorption ability. This work provides a unique activation strategy for designing mesopore-dominated composites, which greatly stimulates the clipping development of high-performance capacitive deionization devices applications.