Regulating the Active Sites of Metal-Phthalocyanine at the Molecular Level for Efficient Water Electrolysis: Double Deciphering of Electron-Withdrawing Groups and Bimetallic

Small. 2023 Mar;19(11):e2207243. doi: 10.1002/smll.202207243. Epub 2022 Dec 21.

Abstract

Implementing a molecular modulation strategy for metallic phthalocyanines (MPc) without losing the activity of the metal center and inducing a multifunction characteristic in electrocatalytic remains a challenge. Herein, a series of 2D CuCo bimetallic polymerized phthalocyanine modified with strong electron-withdrawing groups (CuCoPc-g, g = F, Cl, Br, NO2 ) for water oxidation in the alkaline electrolyte is designed and simply synthesized. The experimental results testify that the bimetallic design can perform electronic adjustment once and introduce the second active sites to get bifunctional characteristics, and then the electronic structure of the active center can be regulated by electron-withdrawing groups for a second time to achieve the optimal state. These electrons that transfer in the active center of inner metal can generate space-charged regions and the design of the polymer can stabilize active site region to maintain long-term electrolytic stability and high activity. This study precisely regulates the electronic structure of MPc at the molecular level and provides insight into the multifunctional design of polymeric macrocyclic electrocatalysts.

Keywords: bimetallic phthalocyanines; electron-withdrawing groups; electrons transfer; overall water splitting; polymerized.