Microporous Polycrystalline Carbon Integrated onto\nthe Surface of Graphene Oxide Functionalized with Amino Acetaldehyde\nDimethyl Acetal to Enhance Electroadsorption Desalination

Capacitive deionization (CDI) has\nbeen considered as a promising\ndesalination technology to solve freshwater shortages because of its\nsuperiority of low energy consumption and high efficiency. The electrode\nmaterials closely determine the desalination performance. Graded porous\ncarbon electrode materials with rich pore structures have significant\nadvantages. Organic molecule-functionalized graphene not only possesses\nthree-dimensional nanostructures but also has the ability to load\nother micro/nanomaterials. With the assistance of ultrasound, activated\ncarbon (AC) can be decomposed into many porous microcrystalline carbons,\nwhich can be loaded onto the surface of functional graphene through\nstrong coupling interface interactions, forming graded porous carbon\nnanomaterials. The CDI device based on this structure will have excellent\nelectroadsorption efficiency. Here, amino acetaldehyde dimethyl acetal-functionalized\ngraphene (ADMA-GO) was synthesized via covalent modification of GO\nand ADMA. Subsequently, ADMA-GO was mixed with various amounts of\ncommercially available AC by an easy ultrasound strategy. The obtained\nthree-dimensional porous composite nanomaterial (GMAC) exhibits a\nsuitable ion-transport pore size distribution and a large specific\nsurface area. The GMAC-based CDI device demonstrated a superior electrosorption\ncapacity of 17.89 mg/g at a 1.60 V applied voltage in a 50 mg/L NaCl\nsolution, 3.52 times that of AC. This electrode also exhibited remarkable\nregeneration and a low energy density of 215.73 J/g. Conclusively,\nthis study provides a strategy to enhance the electrosorption performance\nfor low-concentration saline water (NaCl concentration <60 mg/L)\nin special circumstances, such as water purifiers in pacemakers and\nprecision instruments for integrated circuit boards.