Co-doped Ni-PBA anchored on optimized ZIF-67-derived Co/N-doped hollow carbon framework for high-performance hybrid capacitive deionization

• Published in: Separation and purification technology 2025-06, Vol.358, p.130257, Article 130257
• Main Authors: Li, Bingying, Wang, Yue, Huang, Shunjiang, Fang, Rongli, Zhang, Le, Jin, Ying, Guo, Kaiwen
• Format: Article
• Language: English
• Subjects: 3D conductive framework; Bimetallic CoNi-PBA; Hybrid capacitive deionization; Metal organic framework; N-doped hollow porous carbon
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.130257

[Display omitted] •Co-doped Ni-PBA was tightly anchored on optimized ZIF-67-derived Co/N-doped hollow porous carbon Co/N-HC.•Co/N-HC provides a conductive framework for the in-situ growth CoNi-PBA, facilitating the charge transfer.•PBA@Co/N-HC300//Co/N-HC HCDI cell achieves splendid desalination capability and remarkable stability. Prussian blue analogues (PBAs) are considered to be a promising electrode material for hybrid capacitive deionization (HCDI) due to their open lattice structure, adjustable composition and high theoretical capacity. Nevertheless, the performance of PBAs in practical applications is limited by their low intrinsic conductivity and structural degradation. Herein, we demonstrate an advanced heterostructure CoNi-PBA@Co/N-HC by anchoring cobalt-doped nickel hexacyanoferrate (CoNi-PBA) on cobalt/nitrogen-doped hollow porous carbon (Co/N-HC) derived from cobalt-based metal–organic frameworks (ZIF-67). Co/N-HC as the conductive growth framework of CoNi-PBA can not only promote the rapid charge transfer and efficient ion diffusion, but also mitigate the structural degradation of CoNi-PBA crystals during ion intercalation/deintercalation. Moreover, the doped Co in CoNi-PBA is derived from Co/N-HC, allowing the heterostructures to form more stable and tighter interconnections. Therefore, the optimal PBA@Co/N-HC300 electrode exhibits reduced equivalent series resistance (Rs 1.10 Ω  DNa+(PBA) 4.65 × 10−18) and exceptional electrochemical stability (99% capacitance retention, 500 times CV tests). Correspondingly, the HCDI cell PBA@Co/N-HC300//Co/N-HC demonstrates good Na+ removal capacity (33.37 mg·g−1), excellent charge efficiency (83.65%), diminished energy consumption (0.657 kWh kg−1-NaCl) and improved cycle stability (90.8% capacity retention, 40 cycles).