Enhanced redox kinetics of Prussian blue analogues for superior electrochemical deionization performance.

Prussian blue analogues (PBAs), representing the typical faradaic electrode materials for efficient capacitive deionization (CDI) due to their open architecture and high capacity, have been plagued by kinetics issues, leading to insufficient utilization of active sites and poor structure stability. Herein, to address the conflict issue between desalination capacity and stability due to mismatched ionic and electronic kinetics for the PBA-based electrodes, a rational design, including Mn substitution and polypyrrole (ppy) connection, has been proposed for the nickel hexacyanoferrate (Mn-NiHCF/ppy), serving as a model case. Particularly, the theoretical calculation manifests the reduced bandgap and energy barrier for ionic diffusion after Mn substitution, combined with the increased electronic conductivity and integrity through ppy connecting, resulting in enhanced redox kinetics and boosted desalination performance.

Nanoarchitectonics of ultrafine molybdenum carbide nanocrystals into three-dimensional nitrogen-doped carbon framework for capacitive deionization.

Molybdenum carbide (MoC) has emerged as a promising material for capacitive deionization (CDI), but the poor electrochemical kinetics in conventional MoC owing to the bulk structure and low electric conductivity limit its CDI performance. To address this challenge, herein, we develop a novel strategy to synthesize ultrafine MoC nanocrystals that are embedded within a three-dimensional nitrogen-doped carbon framework (NC/MoC). This synthesis method involves the space-confined pyrolysis of molybdate precursors within metal-organic frameworks (MOFs).