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Anderson-type ([XM6O24]n−) polyoxometalates (POMs) are a class of polymetallic-oxygen cluster inorganic compounds with special structures and properties. They have been paid extensive attention by researchers now, due to their chemical modification and designability, which have been widely applied in the fields of materials, catalysis and medicine. In contemporary years, the application of Anderson-type POMs in catalytic organic oxidation reaction has gradually shown great significance for the research of green catalytic process. In this paper, we investigate the application of Anderson-type POMs in organic synthesis reaction, and these works are summarized according to the different structure of POMs. This will provide a new strategy for further investigation of the catalytic application of Anderson-type POMs and the study of green catalysis. [ABSTRACT FROM AUTHOR]

Adipic acid is an important raw chemical for the commercial production of polyamides and polyesters. The traditional industrial adipic acid production utilizes nitric acid to oxidize KA oil (mixtures of cyclohexanone and cyclohexanol), leading to the emission of N2O and thus causing ozone depletion, global warming, and acid rain. Herein, we reported an organically functionalized β-isomer of Anderson polyoxometalates (POMs) nanocluster with single-atom Mn, β-{[H3NC(CH2O)3]2MnMo6O18}- (1), as a highly active catalyst to selectively catalyze the oxidation of cyclohexanone, cyclohexanol, or KA oil with atom economy use of 30% H2O2 for the eco-friendly synthesis of adipic acid. The catalyst has been characterized by single crystal and powder XRD, XPS, ESI-MS, FT-IR, and NMR. A cyclohexanone (cyclohexanol) conversion of >99.9% with an adipic acid selectivity of ~97.1% (~85.3%) could be achieved over catalyst 1 with high turnover frequency of 2427.5 h-1 (2132.5 h-1). It has been demonstrated that the existence of Mn3+ atom active site in catalyst 1 and the special butterfly-shaped topology of POMs both play vital roles in the enhancement of catalytic activity. [ABSTRACT FROM AUTHOR]

Formamides represent an abundant class of compounds in organic synthesis. They can be made efficiently by the direct catalytic coupling of methanol with amines in the presence of metal-based catalysts. However, these catalysts require complicated organic ligands, susceptible to oxidative self-degradation, restricting their practical applications. Here, we describe an inorganic ligand-supported chromium (III) catalyst, (NH4)3[CrMo6O18(OH)6], which consists of a central chromium (III) single-atomic core supported by a cycle-shaped inorganic ligand consisting of six MoVIO6 octahedra, shows excellent activity and selectivity. Various primary amines and secondary amines are successfully transformed into the corresponding formamides under mild conditions, and the formylation of primary diamines is also achieved. The chromium catalyst can be reused several times with little loss of the activity. Mechanistic insight is provided based on the observation of an intermediate and control experiments. Several catalytic methods for N-formylation of amines using noble metals or manganese pincer complexes are known. Here an air-stable and reusable chromium-based polyoxometalate is shown to catalyze the N-formylation of amines and diamines using methanol and hydrogen peroxide. [ABSTRACT FROM AUTHOR]

[Display omitted] • POM-ZnFe 2 O 4 hybrid is reported first time for overall water splitting. • POM-ZnFe 2 O 4 hybrid delivers extraordinary performance for OER and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. Electrocatalysts play an important role to increase the energy conversion efficiency of electrolysis processes. In this study, a heterostructure of zinc iron oxide (ZnFe 2 O 4) and polyoxometalate (POM) nanoplates (POM–ZnFe 2 O 4) was fabricated for the first time by a hydrothermal process. The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) analysis of POM–ZnFe 2 O 4 furnished low overpotentials of 268 and 356 mV, and 220 and 290 mV to achieve current densities of 20 and 50 mA cm−2, respectively. In addition, an electrolytic cell composed of a POM–ZnFe 2 O 4 cathode and anode required an operating voltage of 1.53 V to deliver a current of 10 mA cm−2. The improved electrochemical performance of POM–ZnFe 2 O 4 compared to commercial and recently reported catalysts is attributed to the high electrocatalytically active surface area, modulation in the electronic and chemical properties and the formation of heterojunction of ZnFe 2 O 4 and POM, which are vital for accelerating HER and OER activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel 3D nano-assembly of NiCo 2 S 4 /PANI@PW 12 /rGO hybrid is reported first time. • NiCo 2 S 4 /PANI@PW 12 /rGO hybrid delivers extraordinary performance for LIB and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. Engineering hierarchical nanostructures with enhanced charge storage capacity and electrochemical activity are vital for the advancement of energy devices. Herein, a highly ordered mesoporous three-dimensional (3D) nano-assembly of Nickel Cobalt Sulphide/Polyaniline @Polyoxometalate/Reduced Graphene Oxide (NiCo 2 S 4 /PANI@POM/rGO) is prepared first time via a simple route of oxidative polymerization followed by a hydrothermal method. Morphological analysis of the resulting hybrid reveals the sheet-like structures containing a homogeneous assembly of PANI@POM and NiCo 2 S 4 on the graphene exterior maintaining huge structural integrity, large surface area and electrochemically active centres. The electrochemical analysis of the nanohybrid as the anode of the lithium-ion battery (LIB) has delivered ultra-huge reversible capacity of 735.5 mA h g−1 (0.1 A g−1 after 200 cycles), superb capacity retention (0.161% decay/per cycle at 0.5 A g−1 for 1000 cycles), and significant rate capability (355.6 mA h g−1 at 2 A g−1). The hydrogen evolution reaction (HER) measurement also proves remarkable activity, extremely low overpotential and high durability. The extraordinary performance of the nanohybrid is due to the presence of abundant electroactive centres, high surface area and a large number of ion exchange channels. These outstanding results prove the advantages of a combination of NiCo 2 S 4 , graphene sheets, and PANI@POM in energy devices. [ABSTRACT FROM AUTHOR]

Abstract: A novel polyoxometalate-based organic–inorganic hybrid compound, [Co(bpy)3]2 [Mo6O19] [β-(H2Mo8O26)]·4H2O (1), have been hydrothermally synthesized and structurally characterized by elemental analysis, single-crystal X-ray diffraction, IR and X-ray photoelectron spectra. Compound 1 represents the first example that racemic complexes coexisting with two kinds of polyoxomolybdate anions in the same crystal architecture, which should be of rare chance that four kinds of complexes crystallizes into a compound. [Copyright &y& Elsevier]

The design of a low-cost, highly efficient and durable electrocatalyst is very important to accelerate the energy conversion efficiency of the electrochemical process. Herein, a simple hydrothermal synthesis of the heterostructure of Wells-Dawson polyoxometalate and zinc iron layered double hydroxide nanosheet is presented for the first time on Ni-foam (ZnFe LDH-P 2 Mo 18 /NF). The electrocatalytic activity of ZnFe LDH-P 2 Mo 18 /NF shows significantly low overpotentials of 275, 330 mV and 273, 367 mV for OER and HER to acquire a current density of 20, 50 mA cm−2 respectively. Additionally, the electrolyzer composed of ZnFe LDH-P 2 Mo 18 /NF cathode and anode shows an attractive voltage of 1.54 V to carry 10 mA cm−2. The better electrochemical performance of the ZnFe LDH-P 2 Mo 18 /NF is ascribed to the variation of electronic and chemical features, growth of electrochemically active surface area/sites because of the construction of heterointerface of Wells-Dawson polyoxometalate and zinc iron LDH. These results further demonstrate the benefits of heterointerface engineering for efficient electrolysis. This study presents a novel hybrid of zinc-iron layered double hydroxide and Dawson polyoxometallate (ZnFe LDH-P 2 Mo 18 /NF) for electrocatalytic water splitting. Notably, ZnFe LDH-P 2 Mo 18 /NF reveals excellent electrocatalytic performance with a large number of electroactive sites, extremely low overpotential, and high durability throughout the water splitting process. [Display omitted] • ZnFe LDH-P 2 Mo 18 hybrid is reported first time for overall water splitting. • ZnFe LDH-P 2 Mo 18 hybrid delivers extraordinary performance for OER and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. [ABSTRACT FROM AUTHOR]

Highlights • Cu dendrites exclusively induced by Anderson type POM (NH 4) 4 [H 6 NiMo 6 O 24 ]. • Chemical association between POMs and Cu NPs was evidenced via XPS and Raman investigation. • Enhanced HER activity with NiMo 6 O 24 @Cu/TNA was achieved. • Mechanism of NiMo 6 O 24 @Cu/TNA electrochemical HER was investigated by Tafel study. • NiMo 6 O 24 @Cu/TNA system shows high stability with enhanced corrosion resistance under neutral and acidic environment. Abstract The design and synthesis of specific functional complex materials as desired catalysts for improved energy conversion and storage are of great importance and with grand challenges. Here, a facile synthesis strategy of Anderson POMs supported Cu dendrites toward electrochemical hydrogen evolution reaction with dramatically decreased overpotential under acidic aqueous condition is established in this work. We present the preparation of well crystallized Cu dendrites through co-electrodeposition on TiO 2 array with Anderson-type POM NiMo 6 O 24. Structural and state of valence investigation of the as-obtained electrocatalyst (NiMo 6 O 24 @Cu/TNA) evidence the specific morphology tunability and modification of Cu dendrites surfaces. During HER course, NiMo 6 O 24 can improve the H+ transfer and further help the H atom absorption which remedies the weakness of insufficient H atom absorption ability of Cu along with its strong electron transfer lowering overpotential upon HER. Therefore, HER with NiMo 6 O 24 @Cu/TNA is considerably enhanced by decreasing related overpotential of 130 mV compared to porous Cu foam. The modification of NiMo 6 O 24 endowed catalysts strong corrosion resistance assuring long term stability. Hence, the proposed strategy possesses improved activity and long term stability upon HER with NiMo 6 O 24 @Cu/TNA as electrocatalyst. Depending on the diversity of POMs, the current feasible and reliable heterogeneous electrocatalysts design with POMs would inspire more effective, low-cost strategies for energy conversion and open the pathway for large scale production. [ABSTRACT FROM AUTHOR]

[Display omitted] • The in-situ confined carbonization of PMo 12 @UiO-66 reduces aggregation and improves conductivity of MoC@PC. • Etching ZrO 2 realizes desired porous MoC@PC with ultra-high specific surface area of 1039 m2·g−1. • Confined phosphorization of MoC@PC gives raise to superhydrophilic MoP-QDs@PC. • The superhydrophilic MoP-QDs@PC exhibits excellent HER performance superior to commercial 20% Pt/C. Fabricating low-cost, earth-enriched and high-performance electrocatalysts for hydrogen evolution reaction (HER) is significant but challenging for the development of a sustainable hydrogen economy. Herein, we report superhydrophilic molybdenum phosphide quantum dots on porous carbon matrix (MoP-QDs@PC) using polyoxometalates (POMs)-contained metal organic frameworks (MOFs) as precursors, where Keggin-type PMo 12 POMs clusters are confined within the zirconium-based UiO-66 MOFs (denoted as PMo 12 @UiO-66). We demonstrate that the as-formed MoC species by in-situ confined carbonization of PMo 12 @UiO-66 can be converted into superhydrophilic MoP-QDs by further phosphorization, while the porous carbon matrix can be converted into rich P and O co-doped carbon matrix, which greatly increase the wettability and the amount of catalytic active sites exposed to the electrolytes. The as-prepared MoP-QDs@PC electrocatalyst exhibits excellent HER performance, which outperforms commercial 20% Pt/C electrocatalyst when overpotential (η) higher than 197 mV and 233 mV under alkaline and acidic conditions, respectively. Depending on the diversity of POMs and MOFs, the current feasible and reliable MoP-QDs@PC electrocatalysts from PMo 12 @UiO-66 precursor would inspire more effective strategies to economical, efficient and stable electrocatalysts for hydrogen evolution. [ABSTRACT FROM AUTHOR]

Abstract: An organic–inorganic hybrid compound, (Bu4N)2[Mo6O18(NAr)] (Ar= p-BrC6H4) has been synthesized via the DCC dehydrating protocol of the reaction of [α-Mo8O26]4− with 4-bromoaniline hydrochloride in anhydrous acetonitrile, which has been characterized by UV–Vis spectra, 1H NMR and single crystal X-ray diffraction study. By comparing the UV–Vis spectra, which were used to monitor the reaction, the optimum preparative condition for this compound was also determined. This compound crystallizes in the monoclinic space group P21/n, which is featured in a terminal para-bromophenylimido group linked to an Mo atom of a hexamolybdate cluster by a Mo–N triply bond. In addition, there are π–π dimerization of the neighboring cluster anions though the parallel aromatic rings in their crystals. [Copyright &y& Elsevier]

Functional material composited of Mo 8 clusters and Cu nanocubes was established with inclusive Cu–O–Mo interfaces which is well defined with electronic structure investigation. The as-prepared interfaces contact functional transition metal oxide clusters and Cu based materials serving as active sites for CO 2 RR with state-of-the-art activity and selectivity to acetate. • Cu 2 Mo 8 O 26 ·2H 2 O (Mo 8) as a novel single crystal was synthesized for the first time. • Cu–O–Mo contact model between POMs and Cu cube surface was experimentally verified. • CO 2 RR with Mo 8 @Cu/TNA shows superior activity to afford acetate with FE 48.68%. • Single carbon coupling mechanism was elaborated via DFT with Cu–O–Mo contact model. Electrocatalytic CO 2 reduction reaction (CO 2 RR) is a promising pathway for storage of renewable electricity and converting CO 2 into value-added products. It's highly desired to obtain acetic acid via CO 2 RR since it's an important chemical feedstock and high energy-density liquid fuel. However, developing highly efficient electrocatalysts for selective CO 2 RR toward acetate remains formidable challenge. We report an interface engineering strategy to modify copper nanocubes with polyoxometalate (POM) to generate Cu–O–Mo interface as active sites for CO 2 RR, achieving state-of-the-art activity with 48.68% acetate formation Faradaic efficiency and current density of ∼110 mA cm−2 at -1.13 V vs RHE. DFT calculations suggest the interface of Cu planes and polyoxometalate clusters with abundant Cu–O–Mo active sites promote the generation of *CH 3 and successive coupling with CO 2 insertion, showing a potential dependence of acetate production. This work provides a Cu–O–Mo interface model for the rational design of earth-abundant metal based electrocatalysts for CO 2 RR and other renewable energy conversions. [ABSTRACT FROM AUTHOR]