Boron-nitride-carbon nanosheets with different pore structure and surface properties for capacitive deionization

Capacitive deionization (CDI) has long been identified as a hopeful solution for adsorption of ions from saline water. Developing stable electrode materials is of great significance to the improvement of CDI performance. In this work, two kinds of boron-nitride-carbon (BCN and MBCN) materials were synthesized for capacitive deionization (CDI) application. The BCN featured with high specific surface area (1097.5 m² g^-1) and positive surface charges (E_pzc of -0.445 V vs. Ag/AgCl) is a good anodic candidate in the CDI device. After configuring with activated carbon, the asymmetric CDI cell exhibits excellent salt adsorption capacity of 17.46 mg g^-1 at supplied voltage of 1.4 V when the feeding NaCl concentration is 300 mg L^-1 and robust cycle performance with 81.4% capacity retention after 50 cycles at supplied voltage of 1.0 V with initial salt concentration of 500 mg L^-1. Overall, in contrast to that of MBCN and carbon materials, the BCN nanosheets demonstrate a high removal capacity and superior cycling stability even at low salt concentration. The stable and positively charged BCN should be a good choice for next generation of high performance CDI electrode materials.