Porous {P₆Mo₁₈O₇₃}-type Poly(oxometalate) Metal–Organic Frameworks for Improved Pseudocapacitance and Electrochemical Sensing Performance

Abstract

{P6Mo18} poly­(oxometalate) (POM) clusters have huge steric hindrance and limited active oxygen atoms, which make them difficult to combine with metal–organic units to form three-dimensional (3D) porous structures. Therefore, functionalization of such POMs has always been a bottleneck that is difficult to break through. In this study, {P6Mo18} POM was successfully grafted on a lock-like metal–organic chain to generate a multiporous coordination polymer, [{Na­(H2O)­(H2btb)}­{Cu4 I(H2O)­(pz)5Cl}­{H2Sr⊂P6Mo2 VMo16 VIO73}]·3H2O (1) (pz = pyrazine; btb = 1,4-bis­(1,2,4-triazole) butane). Meanwhile, a zero-dimensional (0-D) control compound with only btb ligands as counterions, (H4btb)­[H4Sr⊂P6Mo2 VMo16 VIO73]·3H2O (2), was also obtained via a hydrothermal reaction. Compound 1 represents the first basket-type 3D poly­(oxometalate) metal–organic framework (POMOF) assembly, which possesses interpenetrating pores and complex topology. 1-GO-CPE displays improved supercapacitor (SC) performance (the specific capacitance of 929.4 F g–1 at a current density of 3 A g–1 with 94.1% of cycle efficiency after 5000 cycles) compared with 2-GO-CPE and most reported POMOF electrode materials, which may be due to the outstanding redox capability of basket-POM, introduction of metal–organic chains, intersecting pores, and excellent conductivity of graphene. An asymmetric SC device with 1-GO-CPE as the negative electrode exhibits an energy density of 29.7 Wh kg–1 with a power density of 3148.2 W kg–1 and long-lasting cycling life. In addition, 1-GO-GCE as an electrochemical sensor responds to dopamine (DA) at a voltage of 0.40 V and shows lower detection limits (0.19 μM (signal-to-noise ratio (SNR) = 3)), higher selectivity, and good reproducibility in the linear range of 0.56 μM to 0.24 mM. The ability to accurately detect the content of DA in biological samples further proves the feasibility of the sensor in practical applications.

Polyoxometalate-based metal–organic supramolecular architectures derived from two new pyrimidine-amide ligands as supercapacitors and multifunctional electrochemical sensors

“…The impedance caused by the diffusion of ions in the electrode is expressed as the Warburg impedance ( Z w ) in the low frequency region. 45 The high slope of 2 -cpe further confirms its better electrochemical properties and also indicates that the three-dimensional supramolecular structure facilitates ion/electron diffusion transfer. Stability is an important index to evaluate the practical application value of electrode materials.…”

“…It is comparable to some reported excellent supercapacitor materials, which proves that complex 2 has great potential as an electrode material. 25,[47][48][49][50][51][52] Electrochemical sensing properties of complexes 1 and 2…”

Nanomaterial with Core–Shell Structure Composed of {P2W18O62} and Cobalt Homobenzotrizoate for Supercapacitors and H2O2-Sensing Applications

“…To verify whether the sensor is promising for practical applications, real serum samples were selected for hydrogen peroxide content analysis. After diluting the serum samples 20 times with 0.1 M PBS (pH = 7.0) buffer solution, the samples of different concentrations were analyzed by the instrument, and the recovery values were calculated to be between 92.00 and 100.88% ( Figure 6 d), showing that {P 2 W 18 }@Co-BTC-GCE has a certain practical application prospect [ 82 , 83 ].…”

Arsenotungstate-Nanostructure-Based Derivatives with One-Dimensional Tunnels for Electrochemical Capacitors and Electrocatalytic Hydrogen Evolution

“…The electrochemical decomposition of water to produce hydrogen is an efficient, economic, and environmentally friendly method for hydrogen production. 26−29 In order to make the process of electrochemical decomposition of water to produce hydrogen more economical, electrocatalysts 30,31 are usually used to lower the energy barrier of a reaction, speed up the reaction process, and reduce energy losses. So far, although platinum is an excellent hydrogen evolution reaction (HER) electrocatalyst, its extremely low crustal content and extremely high preparation cost greatly hinder its practical application.…”

“…On the other hand, as a renewable energy source, hydrogen energy, has attracted much attention due to its high energy density, abundant natural reserves, and environmental friendliness. , Therefore, hydrogen energy is considered to be the highest potential secondary clean energy source and a supreme form of energy. The electrochemical decomposition of water to produce hydrogen is an efficient, economic, and environmentally friendly method for hydrogen production. − In order to make the process of electrochemical decomposition of water to produce hydrogen more economical, electrocatalysts , are usually used to lower the energy barrier of a reaction, speed up the reaction process, and reduce energy losses. So far, although platinum is an excellent hydrogen evolution reaction (HER) electrocatalyst, its extremely low crustal content and extremely high preparation cost greatly hinder its practical application. , Thus, the preparation of catalysts with high efficiency, low cost, merit stability, and abundant reserves is the most challenging and core topic in HER research. , Recently, various non-noble metal-modified compounds have been developed as catalysts of hydrogen production. , Especially some organic–inorganic composite hybrid materials have been gradually studied in depth in this field and are expected to become representative platinum-free HER electrocatalysts.…”