Hierarchical Hole-enhanced 3D Graphene: Preparation And Investigations On Its Capacitive Deionization Performance

As is well known,there are abundant of water resources on the earth.However,fresh water that can be used directly in human life and production only accounts for 2.5%of this reserve.With the rapid population growth,climate change and industrial development,it is essential to highlight the freshwater scarcity and look for new water resources.Capacitive deionization(CDI),a cost-effective,environmentally friendly and energy-efficient technology,which can achieve low-pressure pumps,non-membrane water purification,is considered to be promissing in the future water treatment.At the same time,the excellent performance in water purification depends not only on advenced water-cleaning technologies,but also the properties of electrode materials.The selection of electrode materials thus has become a hot topic for researchers in the field.Graphene has attracted much scientific interest due to its unique physical and chemical properties,such as superior theoretical conductivity(7200 S m^-1)and larger theoretical specific area(2600 m²g^-1).In this paper,we have prepared hierarchical hole-enhanced 3D graphene foam for further functionalizing the graphene to study its CDI performance.The main research contents are as follows:(1)The CDI test facility was built successfully by referring to a large number of literatures.(2)A novel antifreeze-assisted freezing technique was used to form large-scaled integrated foam.The graphene bridges between the vertical-alined thick graphene walls are positive for the mechanical stability.Moreover,to further enhance the electroadsorption capacity,we have designed and fabricated holey graphene oxide(HGO)self-assembly into a 3D interconnected network.Taking adventage of the tough 3D hierarchical holey structure,this newly designed binder-free electrode material can be also obtained.(3)This electrode material exhibits ultrahigh electrosorption capacity of 29.6 mg/g at 2.0 V...