Evolution of CuCoFe Prussian blue analogues with open nanoframe architectures for enhanced capacitive deionization

Despite remarkable progresses have been made on forming a wide variety of Prussian blue analogues (PBAs), one-pot synthesis of PBAs with extraordinarily complex compositions and structures is still challenging. Herein, preparation of trimetallic PBA containing copper, cobalt, and iron with nanoframe superstructures (CuCoFe-PBA NFs) via a multi-step in-situ structural conversion is reported. Comparable experiments indicate that successful conversion via this route is attributable to a self-templated epitaxial growth triggered by the additional introduction of Cu ions into the reaction system. The optimal composition and three-dimensional (3D) opened nanoframe structure of CuCoFe-PBA NFs offer the electrode with rich redox active species, abundant accessible adsorption sites, and fast ion transport that enhance its capacitive deionization (CDI) performance. As a result, the CuCoFe-PBA NFs demonstrate an exceptional CDI performance with a desalination capacity of 46.8 mg g−1 at an applied potential of 1.4 V and superior cyclability with negligible decay on the desalination capacity even after 100 cycle tests.