Na3(VO)2(PO4)2F nanocuboids/graphene hybrid materials as faradic electrode for extra-high desalination capacity

Abstract

Capacitive deionization (CDI) is considered as a promising desalination technology due to its low energy consumption and no two-second pollution. But the development of traditional CDI is limited by its two drawbacks, which are low deionization capacity and unavoidable parasitic reactions. Hybrid capacitive deionization (HCDI), which is composed of a faradic electrode and an electrical-double-layer electrode, effectively solves the above problem. Herein, we report a typical NASICON material Na3(VO)2(PO4)2F and modify it with rGO, then apply it in HCDI firstly and receive a superior desalination performance. Five samples are prepared by adding different contents GO solution and we choose the best one (NVOPF-4) with the lowest resistance for the desalination tests according to electrochemical performance. The result of desalination shows a high desalination capacity of 175.94 mg·g−1, low energy consumption of 0.35 kWh·kg-NaCl−1, and the energy recovery is 20% at a current density of 25 mg·g−1. NVOPF@rGO displays a promising ability for desalination in capacitive deionization, further confirming NASICON be a suitable material type for HCDI electrode materials.