Large-surface-area porous monolith of graphene for electrochemical capacitive deionization

Abstract

With the increasing severity of the water crisis, electrochemical capacitive deionization has emerged as a promising technology for water purification. Graphene is a powerful candidate among carbon materials for the electrochemical electrode, and monolithic graphene is a high-end material for capacitive deionization considering its potentially large surface area and fast adsorption kinetics. However, monolithic graphene electrode materials still suffer from either weak deionization performances or high manufacturing costs. Herein, a novel electrode material, a porous monolith composed of nitrogen-doped graphene building-blocks, has been developed via low-cost zinc-assisted pyrolysis. The monolith is hydrophilic, possesses a high specific surface area, and has abundant hierarchical mesopores. Remarkable electrochemical capacitive deionization performances are provided by such a graphene monolith, with a salt adsorption capacity of 39.6 mg g⁻¹ and a salt adsorption rate near 3.5 mg g⁻¹ min⁻¹. This development thus underlines the promise of novel monolithic electrode materials for high-efficiency desalination of seawater into freshwater.