Synergistically improved hydroxide ions conduction of quaternized Poly(2.6 Dimethyl-1.4 phenylene Oxide)-Based anion exchange membrane with necklace shaped metal-organic Framework@Carbon nanotube oxide

Abstract

During the development of anion exchange membranes (AEMs), there is a dilemma of mutual restriction relationship between quick hydroxide ions conduction and reinforced alkaline stability. In this research, the necklace shaped metal-organic framework (MOF) crystals decorating carbon nanotube oxide (OCNT) is prepared through the self-assembly process owing to the interfacial tension force and intermolecular hydrogen bonds. The necklace shaped MOF@OCNT is introduced into quaternized poly(phenylene) oxide (QPPO) to synergistically improve hydroxide ions conduction and alkaline stability of the QPPO/MOF@OCNT membrane. The hydroxide ions conduction process is accelerated even at subzero temperature owing to the formation of oriented hydroxide ions conduction channels. Additionally, MOF@OCNT can resist hydroxide radical (OH−) continuous attacks to functional groups in the polymer molecular chains of QPPO. As a result, QPPO/MOF@OCNT exhibits the hydroxide conductivities of 3.20 mS/cm at −25 °C and 44.8 mS/cm at 80 °C. Most importantly, the enhanced alkaline stability is revealed from the ten-cycle hydroxide conductivity and the long-term hydroxide conductivity. After immersing in 2 M potassium hydroxide (KOH) solution for 48 h, the tensile stress of QPPO/MOF@OCNT reaches 24.1 MPa. A single fuel cell with QPPO/MOF@OCNT as the electrolyte exhibits the peak power densities of 0.133 W/cm2 at 30 °C and 0.610 W/cm2 at 60 °C.