Three-dimensional graphene-based hierarchically porous carbon composites prepared by a dual-template strategy for capacitive deionization

Abstract

A three-dimensional graphene-based hierarchically porous carbon (3DGHPC) has been prepared by a dual-template strategy and explored as the electrode for capacitive deionization (CDI). The texture analyses indicate that the incorporation of porous carbon into the three-dimensional graphene (3DG) has constructed a hierarchical pore network with a bimodal pore distribution. Compared to those of the 3DG (250.3 m² g⁻¹, 0.49 cm³ g⁻¹), the 3DGHPC exhibits a higher specific surface area of 384.4 m² g⁻¹ and an improved pore volume of 0.73 cm³ g⁻¹. The electrosorption behavior investigated by electrochemical techniques demonstrates that the 3DGHPC electrode displays superiority in specific capacitance and cyclability, as well as electrical conductivity. The CDI performance evaluated by batch mode experiments at a direct voltage of 1.2 V in a 25 mg L⁻¹ NaCl aqueous solution reveals that the 3DGHPC electrode presents a higher electrosorptive capacity of 6.18 mg g⁻¹ and an increased desalination efficiency of 88.96%. The enhanced deionization properties are deduced to arise from the improved specific surface area and increased pore volume, as well as an elevated electrical conductivity.