No abstract

Polyoxometalates (POMs) are a series of molecular metal compounds based on W and Mo elements, exhibiting excellent physical and chemical properties. POMs have been widely used in the fields of photoelectric materials, catalytic materials, and coordination chemistry. In recent years, POMs have emerged in the field of chemiresistive gas sensors. They can work as electron acceptors and improve the gas-sensing performance of traditional sensing materials by means of capturing electrons from semiconductors, separating electrons produced by light excitation or thermal excitation and delaying the recombination of electrons and holes. So far, the highest sensing sensitivity response of POMs-based chemiresistive gas sensor is 231 to 1 ppm NO2 gas. In this review, an overview is investigated about how POMs have evolved as sensing materials in gas sensors. First, some POMs and POMs-based sensing materials in recent years are introduced and classified. After that, brief analyses for each kind of sensing materials are provided. Then we compare the reported POMs-based sensors in different sensing parameters. Finally, the future outlooks are discussed on the basis of the current developments. This work is the first comprehensive overview of POMs-based chemiresistive gas sensors. This work can provide valuable information for developing high-performance POMs-based gas sensors.

Two new calix[4]resorcinarene-based metal-coordinated cages have been synthesized through tuning metal ions, where they featured catalytic activities for the Knoevenagel condensation reaction under solvent-free conditions.

With their adjustable structures and diverse functions, polyoxometalate (POM)‐resorcin[4]arene‐based inorganic–organic complexes are a kind of potential multifunctional material. They have potential applications for lithium ion batteries (LIBs). However, the relationship between different coordinated metal ions and electrochemical performance has rarely been investigated. Here, three functionalized POM‐resorcin[4]arene‐based inorganic–organic materials, [Co2(TMR4 A)2(H2O)10][SiW12O40]⋅2 EtOH⋅4.5 H2O (1), [Ni2(TMR4 A)2(H2O)10][SiW12O40]⋅4 EtOH⋅13 H2O (2), and [Zn2(TMR4 A)2(H2O)10][SiW12O40]⋅2 EtOH⋅2 H2O (3), have been synthesized. Furthermore, to enhance the conductivities of these compounds, 1–3 were doped with reduced graphene oxide (RGO) to give composites 1@RGO‐3@RGO, respectively. As anode materials for LIBs, 1@RGO‐3@RGO can deliver very high discharge capacities (1445.9, 1285.0 and 1095.3 mAh g−1, respectively) in the initial run, and show discharge capacities of 898, 665 and 651 mAh g−1, respectively, at a current density of 0.1 A g−1 over 100 runs. More importantly, the discharge capacities of 319, 283 and 329 mAh g−1 were maintained for 1@RGO‐3@RGO even after 400 cycles at large current density (1 A g−1).