One-step synthesis of high surface-area honeycomb graphene clusters for highly efficient capacitive deionization

Capacitive deionization (CDI) can realize ion adsorption efficiently by forming electrochemical double layers on electrode surfaces. This potential-driven adsorption process requires electrode materials possessing a large surface area as well as a rapid and easy electrolyte-diffusion pathway. In this respect, we designed and synthesized a novel honeycomb graphene cluster (HGC) based on one-step exothermic reaction between liquid lithium and carbon monoxide gas. The obtained HGC electrode, as both cathode and anode in a CDI cell, exhibited excellent desalination performance. Its electrosorption capacity reached 14.08 mg/g in a batch-mode system with continuously recycled 28 ml of 5 mM NaCl solution. This high-level desalination ability can be attributed to the effective utilization of HGC materials: its large surface area of up to 1962 m2/g can provide abundant sites for ions adsorption, and three-dimensional mesoporous frameworks can facilitate ion transport. Thus, HGC electrodes can achieve electrosorption capacity of twice that of activated-carbon electrodes, indicating promising applications in the CDI field.