Design and fabrication of mesoporous graphene via carbothermal reaction for highly efficient capacitive deionization

• Mesoporous graphene was prepared via carbothermal reaction in nitrogen atmosphere.
• Mesoporous graphene was used as electrode material for capacitive deionization.
• Mesoporous graphene exhibits better deionization performance than graphene.

Here a facile strategy was proposed to prepare graphene (GE) sheets with unique mesoporous morphology (denoted as mGE) via a simple carbothermal reaction by using KMnO4 as the etching agent. The morphology, structure and electrochemical properties of mGE were investigated by scanning electron microscopy, transmission electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy. The electrosorption performance of mGE in NaCl solution was studied and compared with GE. The results show that mGE electrode exhibits a high electrosorption capacity of 6.38 mg g−1 when the initial NaCl concentration is ∼75 mg L−1 and applied voltage is 1.2 V, which is about 2.3 and 1.5 times of those of GE (2.76 mg g−1) and recently reported microporous GE (∼4 mg g−1), respectively, and also higher than those of other carbon materials in the literatures, due to short ion diffusion path, large accessible surface area and low charge transfer resistance offered by its novel mesoporous structure. Therefore, it is believed that mGE is a promising candidate for practical capacitive deionization applications.