A coordination polymer based on dinuclear (pyrazinyl tetrazolate) copper(ii) cations and Wells–Dawson anions for high-performance supercapacitor electrodes

Abstract

A new coordination polymer, (H₂bpe)(Hbpe)₂{[Cu(pzta)(H₂O)][P₂W₁₈O₆₂]}·5H₂O (1) (pztaH = 5-(2-pyrazinyl) tetrazolate, bpe = bis(4-pyridyl)ethylene), was synthesized by the hydrothermal method. The structure was determined by single crystal X-ray diffraction analyses and further characterized by the SEM, EDS, BVS, FTIR, and PXRD techniques. In 1, the [P₂W₁₈O₆₂]⁶⁻ (P₂W₁₈) clusters as bidentate connectors link [Cu(pzta)(H₂O)]₂⁴⁺ dinuclear copper(II) complexes to form inorganic–organic chains. These chains and the [H₂bpe]²⁺ counter-cations are fused together via hydrogen bonding to form a 3D supramolecular architecture. While 1 was employed as the electrode in a supercapacitor, the cycling stability (90.7% capacitance retention after 1000 circles) and specific capacitance (168 F g⁻¹ at a current density of 5 A g⁻¹) of the 1-based electrode are better than those of the parent α-K₆P₂W₁₈O₆₂-based electrode, demonstrating more outstanding electrochemical performances of 1. Besides, the 1-based electrode showed excellent electrocatalytic activities towards the reduction of H₂O₂ and KIO₃.