Quantum mechanics

Engineering

Nanoparticle

Prussian blue

Stacking

Electrochemistry

Metallurgy

Materials science

Nanosheet

Capacitive deionization

Biochemistry

Nano-

Chemical engineering

Physical chemistry

Capacitive sensing

Physics

Nanotechnology

Organic chemistry

Membrane

Desalination

Composite material

Charge (physics)

Chemistry

Electrode

Nickel

Electrical engineering

Chemical Engineering Journal

Prussian blue analogues (PBAs), as a kind of metal–organic framework–like materials, has attracted great attention in capacitive deionization (CDI) field due to excellent redox activity, but its desalination performance, especially its desalination rate, is greatly limited due to its poor electrical conductivity. Hybridization of PBAs with MXene can potentially solve this problem, but still remains intrinsic limitation, such as poor vertical charge transfer between nano-sheets. Herein, we engineered a three-dimensional (3D) charge transfer pathway in nickel hexacyanoferrate (NiHCF)/MXene through in situ close packing of NiHCF nanoparticles on MXene nano-stacking by electrostatic attraction. Compared to charge transfer mode in two-dimensional (2D) nano-sheets, 3D MXene nano-stacking can not only have excellent conductivity like MXene to provide horizonal charge transfer pathway alongside nano-sheets, but also possess unique vertical charge transfer pathway between nano-sheets. As a result, the NiHCF/MXene exhibits a superior desalination performance with a high desalination capacity of 30 mg g−1, ultrahigh desalination rate of 9.5 mg g−1 min−1 and good cycling stability over 30 cycles. This work demonstrates an effective way to address the poor CDI performance of nickel hexacyanoferrate nanoparticles by employing 3D MXene nano-stacking as charge transfer support, and is of significance to be applied for other nanoparticle materials.

Three-dimensional charge transfer pathway in close-packed nickel hexacyanoferrate−on−MXene nano-stacking for high-performance capacitive deionization