An Overview on the Facile and Reversible Cations Intercalation in Nickel-Hexacyanoferrate Open Framework

摘要

The paper reports a detailed study about the influence of the electrolyte composition in nickelhexacyanoferrate (NiHCF) electrochemical behavior. Shapes and positions of the CV waves arestrongly related to the cation of the supporting electrolyte, which undergoes intercalation/deintercalation during the redox process. The electrochemical behavior of NiHCF has been characterizedin different electrolyte solutions containing either pure monovalent or trivalent metal nitrates. Nickelhexacyanoferrate permits the reversible insertion of a wide variety of monovalent, divalent andtrivalent ions in aqueous solution; the characteristic potential Ep of the cathodic process depends uponthe nature of the intercalated cation. Electrochemical measurements demonstrate the unprecedentedfast kinetics of trivalent ion insertion associated with this material. The reported findings represent thefirst systematic step toward understanding the principles of multivalent charge screening and provide anovel cation intercalation mechanism in NiHCF, assisted by both water molecules and ferrocyanidevacancies. The synergistic mechanism can reduce the electrostatic repulsion and provide a preferentialpath for the rapid cation intercalation.