Bio-composite nanoarchitectonics for graphene tofu as useful source material for capacitive deionization

The development of low cost, naturally sustainable, and high-performance electrode materials is the primary issue that determines the large-scale application of capacitive deionization (CDI). In this work, the nitrogen-doped activated porous carbon decorated by 3D interconnected graphene (NAPC/G) was synthesized by pre-carbonization and KOH activation of soy milk and graphene oxide composite gel (graphene tofu). The NAPC has an ultra-high specific surface area (SSA) of 2993.5 m 2  g −1 , rich micro-mesoporous structure, and good hydrophilicity . In addition, the 3D graphene network enhances the conductivity of the composite. Therefore, benefited from the synergetic effect of abundant ions adsorption sites and improved conductivity, the specific capacitance of NAPC/G electrodes is up to 370 F g −1 and maintains capacitance retention of 97% after 3000 cycles. For CDI electrode materials, the salt adsorption capacity (SAC), desalination rate, and cycle stability are the three important parameters. In this work, the NAPC/G electrode achieves an high SAC of 38.5 mg g −1 , large desalination rate of 6.6 mg g −1  min −1 and good cycle stability that desalination performance remains 93.5% after 50 cycles. This research provides an effective way to promote the sustainable large-scale application of CDI.