Various hydrophilic carbon dots doped high temperature proton exchange composite membranes based on polyvinylpyrrolidone and polyethersulfone

Abstract

Novel organic-inorganic composite membranes were prepared conveniently by compositing of carbon dots (CDs) possessing different hydrophilicity into the low cost blended polymers of polyvinylpyrrolidone (PVP) and polyethersulfone (PES). The hydrophilicity of the CDs arises from its surface hydrophilic groups, which could be adjusted by controlling the reaction temperature and duration time. A series of homogeneous composite membranes doping with different hydrophilic CDs of up to about 10 wt% were obtained. Comprehensive characterizations were made in order to know the influence of different hydrophilic CDs on the properties of the prepared membranes. It is found that the doped CDs could cause the change in microphase separation and benefit proton conduction of the composite membranes. The more doped CDs, the higher the conductivity. A highest conductivity of 0.086 S cm−1 was reached by a composite membrane doped with both hydrophilic and hydrophobic CDs. Moreover, the incorporated CDs brought on the changes in properties of the composite membranes including free volume, hydrophilicity, acid doping level and swelling. A single fuel cell test was made based on the CDs blended membrane and indicating its potential to be used as the membrane electrolyte in high temperature proton exchange membrane fuel cells.