Scalable NH4V4O10 clusters as functional network nodes on toughened porous carbon nanofibers for hybrid capacitive deionization

Layered vanadium-based compound (e.g., NH4V4O10) is acknowledged as an outstanding candidate for intercalation pseudocapacitance electrode of capacitive deionization (CDI) cells. However, the directed production of high-efficiency NH4V4O10-based self-supporting CDI electrodes and their structure–activity connection warrant more in-depth study. Herein, the delicate design and controllable construction of NH4V4O10 clusters on the freestanding porous carbon nanofiber (PCNF) scaffolds (the composite PCNFs/NH4V4O10 is defined as CNVO) using a new organic reducing agent of citric acid is proposed, where NH4V4O10 clusters as functional network nodes can improve the mechanical toughness, electrochemical capacitive performance, and desalination capability of the CNVO hybrid. The Na+ adsorption mechanism on CNVO is confirmed by ex-situ experimental characterizations and density functional theory (DFT) calculations. The hybrid CDI (HCDI) cell composed of the optimized CNVO cathode and PCNFs anode shows a desirable desalination capacity (45.07 mg g−1), a superior salt removal rate (16.4 mg g−1 min−1), an excellent energy utilization, and an acceptable cyclic regeneration ability in 500 mg L-1 NaCl solution. More importantly, the assembled HCDI system is promising for the desalination of reclaimed water from the printing and dyeing enterprise. This work highlights a scalable strategy that is experimentally and theoretically feasible to design and fabricate high-efficiency CDI electrodes.