Electrodeposited Manganese Dioxide/Activated Carbon Composite As a High-Performance Electrode Material for Capacitive Deionization

Abstract

Electrode materials are a crucial component for achieving high desalination performance via capacitive deionization (CDI). In the present work, we have successfully fabricated a manganese dioxide (MnO 2 )/activated carbon (AC) composite electrode using an anodic electrodeposition technique. Surface characterization confirms the presence of electrodeposited MnO 2 on the AC surface with an amorphous structure and improved wetting behavior. Cyclic voltammetry and galvanostatic charge/discharge measurements indicate that the MnO 2 /AC composite electrode exhibits a high specific capacitance (77.6 F g –1 at 5 mV s –1 ), rate capability, and excellent cycling reversibility for capacitive charge storage. Furthermore, the salt electrosorption capacity is investigated using batch mode experiments at a working voltage of 1.0 V in a 0.01 M NaCl solution. The MnO 2 /AC composite electrode presents a superior electrosorption capacity of 9.3 mg g –1, which is approximately 1.6-fold higher than that of the pure AC electrode (5.7 mg g –1 ). This significant improvement can be attributed to the mixed capacitive-Faradaic process, corresponding to the combination of the double-layer charging of the high specific surface area (625 m 2 g –1 ) and the pseudocapacitive redox reaction of MnO 2 . Therefore, the electrodeposited MnO 2 /AC composite is a potential electrode material for high-performance CDI.