Manganese Oxide Nanoparticles Decorated Ordered Mesoporous Carbon Electrode for Capacitive Deionization of Brackish Water

Abstract

Capacitive deionization (CDI) is a promising electrosorption technique for removing the salt ions from brackish water by applying an electrical potential across two electrodes. Ordered mesoporous carbon with suitable pore size, good cross-linked porous structure and high surface area, is considered to be a promising electrode material. In this work, manganese oxide nanoparticles decorated ordered mesoporous carbon were synthesized via an impregnation method. The nitrogen sorption analysis and TEM results show that the structure of carbon host is maintained well after manganese oxides loading. However, the majority pore-size and the specific surface area of the hybrids decrease with the increasing of loading amount, indicating the successful entrance of the guest manganese oxide nanoparticles into the mesoporous carbon channels. The influences of the heat-treatment and the guest loading amount on the phases of the manganese oxides were also investigated. The electrosorption performance was investigated in a CDI batch. Compared with the pristine ordered mesoporous carbon, the electrochemical and electrosorption performances of the hybrids are importantly improved. Particularly, the hybrids with 15 wt% Mn heat-treated at 400°C exhibit the best specific capacitance (83.9 F/g) in 1 mol/L NaCl electrolyte, electrosorption capacity (5.4 mg/g) under an applied potential of 1.2 V.