Electrodeposition fabrication of graphene oxide/α-MnO2/polyaniline hierarchical porous electrodes with large hybrid specific capacitance for efficient U(VI) electrosorption

Abstract

The radioactive pollution caused by the excessive discharge of uranium-containing wastewater generated from nuclear industry posed harmful effect to the ecological environment and human health. Herein, the electrodeposition of polyaniline on graphene oxide/α-MnO2 surface was conducted to fabricate novel hierarchical porous graphene oxide/α-MnO2/polyaniline (GMP) electrodes with large specific capacitance for U(VI) electrosorption through hybrid capacitance deionization (HCDI). As expected, the prepared GMP have high specific capacitance, small electrochemical impedance, and excellent electrosorption performance. Among the different GMP composites, GMP-2 presents the highest specific capacitance (303.85 F/g) and largest electrosorption capacity of U(VI) (330.41 mg/g at 0.9 V and pH4.0), indicating that its electrosorption capacity is closely related to the specific capacitance. Moreover, GMP-2 showed good selectivity for U(VI) electrosorption through pseudocapacitive mechanism. The XPS and FTIR characterization indicated that apart from hybrid capacitance (EDL and pseudocapacitance) mechanism, complexation and electrostatic interactions were also involved for U(VI) capture. The GMP-2 electrode is facile to fabricate and has excellent electrosorption performance, which could be used in HCDI for radioactive wastewater treatment.