Polyaniline coated MOF-derived Mn2O3 nanorods for efficient hybrid capacitive deionization.

ABSTRACT

Mn-based oxides are efficient pseudocapacitive electrode materials and have been investigated for capacitive deionization (CDI). However, their poor conductivity seriously affects their desalination performance. In this work, polyaniline coated Mn2O3 nanorods (PANI/Mn2O3) are synthesized by oxidizing a Mn-based metal organic framework (MOF) and subsequent in-situ chemical polymerization. The polyaniline not only acts as a conductive network for faradaic reactions of Mn2O3, but also enhances the desalination rate. PANI/Mn2O3 has a specific capacitance of 87 F g-1 (at 1 A g-1), superior to that of Mn2O3 nanorod (52 F g-1 at 1 A g-1). The hybrid CDI cell constructed with a PANI/Mn2O3 cathode and an active carbon anode shows a high desalination capacity of 21.6 mg g-1, superior recyclability with only 11.3% desalination capacity decay after 30 desalination cycles and fast desalination rate of 2.2 mg g-1 min-1. PANI/Mn2O3 is a potential candidate for high performance CDI applications.