Abstract

To research the application of polyoxometalates (POMs)-based supramolecular crystalline materials in supercapacitors, two new compounds, H₃PW^VI₁₂O₄₀·(BPE)_2.5·3H₂O(1) and H₃PMo^VI₁₂O₄₀·(BPE)_2.5·3H₂O (2) (BPE = 1,2-Bis(4-pyridyl)ethylene) have been synthesized by a one-step hydrothermal method. Their structures are determined by single-crystal X-ray diffraction analysis and further characterized by FTIR spectroscopy, powder X-ray diffraction, and bond valence sum analysis. The POMs cluster ([H₃PW^VI₁₂O₄₀] or [H₃PMo^VI₁₂O₄₀]) acts as a connector to connect five BPE units through hydrogen bonds, generating a three-dimensional structure. The capacitance performance of these two compounds is tested by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. Compared with compound 1 and parent H₃PMo^VI₁₂O₄₀, compound 2 shows better electrochemical performances with a capacitance of 137.5 F g^–1 at 2 A g^–1. Compound 2 also has good cycle stability at a current density of 10 A g^–1 and still has an initial capacitance of 92% after 1000 cycles. This work shows that hybrid supramolecular crystal materials based on polyoxometalates may provide an alternative way to improve the performance of POMs-based capacitor electrode materials.

Graphic abstract

Two POMs-based supramolecular crystalline materials were synthesized by a hydrothermal method. The supercapacitor performance of these two compounds is better than their parents POMs(PW₁₂ and PMo₁₂). Among them, compound 2 displays specific capacitance (137.5 F g^–1 at 2 A g^–1) and better cycle stability (92.0% after 1000 cycles).

中文翻译：

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超级电容器电极基于Keggin基多金属氧酸盐和1,2-双（4-吡啶基）乙烯的三维超分子晶体材料

摘要

为了研究基于多金属氧酸盐（POMs）的超分子晶体材料在超级电容器中的应用，两种新化合物H ₃ PW ^VI ₁₂ O ₄₀ ·（BPE）_2.5 · 3H ₂ O（1）和H ₃ PMo ^VI ₁₂ O ₄₀ ·（ BPE）_2.5 · 3H ₂ O（2）（BPE = 1,2-双（4-吡啶基）乙烯）是通过一步水热法合成的。它们的结构通过单晶X射线衍射分析确定，并通过FTIR光谱，粉末X射线衍射和键合价和分析进一步表征。POM簇（[H ₃ PW ^VI ₁₂ O ₄₀ ]或[H ₃ PMo ^VI ₁₂ O ₄₀ ]）充当连接器，通过氢键连接五个BPE单元，从而产生三维结构。这两种化合物的电容性能通过循环伏安法，恒电流充放电和电化学阻抗谱进行了测试。与化合物1和母体H相比₃ PMO ^VI ₁₂ ø ₄₀，化合物2所表现出更好的电化学性能用的137.5 F G的电容^-1在2A克^-1。化合物2在10 A g ^–1的电流密度下也具有良好的循环稳定性，在1000次循环后仍具有92％的初始电容。这项工作表明，基于多金属氧酸盐的杂化超分子晶体材料可能会提供另一种方法来提高基于POMs的电容器电极材料的性能。

图形摘要

通过水热法合成了两种基于POMs的超分子晶体材料。这两种化合物的超级电容器性能均优于其母体POM（PW ₁₂和PMo ₁₂）。其中，化合物2个显示比电容（137.5 F G ^-1在2A克^-1）和更好的循环稳定性（1000次循环后92.0％）。