In-situ growth of Ni, Co-Prussian blue nanocubes on molten salt etched lamellar Ti3C2Tx/Ni for enhanced hybrid capacitive deionization

Abstract

The design and development of high-performance electrode materials are crucial for improving the desalination efficiency of hybrid capacitive deionization (HCDI). In this study, a Ti3C2Tx/Ni/NiCo-PBA composite is synthesized by in-situ growing NiCo Prussian blue (PB) nanocubes on Ti3C2Tx/Ni sheets, serving as an electrode for HCDI. The Ti3C2Tx sheets provide excellent conductivity and a suitable substrate for the growth of NiCo-PBA nanocubes. The Ni nanoparticles help prevent the oxidation of Ti3C2Tx sheets, and provide a source of Ni for NiCo-PBA synthesis. Additionally, the NiCo-PBA nanocubes effectively inhibit re-stacking of Ti3C2Tx sheets, enlarge crystal lattice spacing, and facilitate diffusion and storage of salt ions. Consequently, the AC||Ti3C2Tx/Ni/NiCo-PBA HCDI device exhibits a high salt removal capacity of 36.62 mg g−1, low energy consumption of 11.14 Wh m−3, and water recovery of 61.86 %. Importantly, the AC||Ti3C2Tx/Ni/NiCo-PBA device achieves a good salt removal capacity of 53.22 mg g−1 in a high concentration NaCl solution (2000 μS cm−1). After 20 cycles, the desalination capacity remains stable, and the structure of Ti3C2Tx/Ni/NiCo-PBA is intact, indicating excellent cycling stability. Additionally, the desalination mechanism of Ti3C2Tx/Ni/NiCo-PBA electrode is thoroughly investigated.