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Electroreduction of greenhouse gas CO2 into value-added fuels and chemicals provides a promising pathway to address the issues of energy crisis and environmental change. However, the regulations of the selectivity towards C2 product and the competing hydrogen evolution reaction (HER) are major challenges for CO2 reduction reaction (CO2RR). Here, we develop an interface-enhanced strategy by depositing a thin layer of nitrogen-doped graphene (N-G) on a Cu foam surface (Cu-N-G) to selectively promote the ethanol pathway in CO2RR. Compared to the undetectable ethanol selectivity of pure Cu and Cu@graphene (Cu-G), Cu-N-G has boosted the ethanol selectivity to 33.1% in total Faradic efficiency (FE) at −0.8 V vs. reversible hydrogen electrode (RHE). The experimental and density functional theory (DFT) results verify that the interconnected graphene coating can not only serve as the fast charge transport channel but also provide confined nanospace for mass transfer. The N doping can not only trigger the intrinsic interaction between N in N-G and CO2 molecule for enriching the local concentration of reactants but also promote the average valence state of Cu for C-C coupling pathways. The confinement effect at the interface of Cu-N-G can not only provide high adsorbed hydrogen (Had) coverage but also stabilize the key ⋆HCCHOH intermediate towards ethanol pathway. The provided interface-enhanced strategy herein is expected to inspire the design of Cu-based CO2RR electrocatalysts towards multi-carbon products. [ABSTRACT FROM AUTHOR]

A newly prepared nano-organic–inorganic hybrid compound, videlicet [HPDCD]5[BW12O40]·3H2O (HPDCD = hydrolyzed and protonated 2-cyanoguanidine) (1), has been prepared under reflux condition and analyzed by FT-IR and 1H NMR spectroscopies, TG–DT analysis, FE-SEM, cyclic voltammetry, elemental analyses and also single-crystal and powder X-ray diffraction. Hydrogen bonding is the crucial agent in 1 hybrid structure as can be seen from the X-ray data. In this compound, 3D cage-like cavities are constructed by HPDCD counter-ions through hydrogen bonding. Four types of hydrogen bonds in compound 1 lead to the formation of cage-like cavities. [BW12O40]5− clusters are located into compound 1 cage-like cavities. Five types of HPDCD units create cage-like cavities according to which two types of BW12 clusters are placed between the cavities. Moreover, according to powder X-ray diffraction and field emission SEM analyses, the nano-size of 1 cluster has been confirmed. Furthermore, compound 1 has been considered in terms of the electrocatalytic activity and photocatalytic property. [ABSTRACT FROM AUTHOR]

A new organic-inorganic hybrid consisting of Keggin-type polyoxometalate ([BW12O40]5−) and protonated piperazine, namely [H5O2]2[Hpip]2.5[BW12O40]·4H2O (pip = piperazine, C4H10N2) (1), has been created under reflux state and identified through material identification devices like single-crystal crystallography, FT-IR and 1H-NMR spectroscopies, Powder XRD, TG-DT Analysis, Field Emission SEM, elemental-analysis and cyclic voltammetry. Crystallography investigation exhibits that the main factor in the formation of 1 is the numerous number of hydrogen bonding between organic and inorganic species. The arrangement of Hpip groups creates holes in which the [BW12O40]5− clusters fit into the holes. Furthermore, the electrochemical and photochemical attributes of 1 have been considered, and the outcomes present that 1 owns privileged electrocatalytic activity against the reduction of nitrite ions as well as an appropriate photochemical effect on methylene blue (MB) dye depredation. A new organic-inorganic hybrid consisting of Keggin-type polyoxometalate ([BW12O40]5-) and protonated piperazine, namely [H5O2]2[Hpip]2.5[BW12O40]·4H2O (pip = piperazine, C4H10N2) (1), has been created under reflux state. The electrochemical and photochemical attributes of 1 have been considered, and the outcomes present that 1 owns privileged electrocatalytic activity against the reduction of nitrite ions as well as an appropriate photochemical effect on methylene blue (MB) dye depredation. [ABSTRACT FROM AUTHOR]

An emerging method for effectively improving the catalytic activity of metal oxide hybrids involves the creation of metal oxide interfaces for facilitating the activation of reagents. Here, we demonstrate that bilayer vesicles formed from a hexavanadate cluster functionalized with two alkyl chains are highly efficient catalysts for the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) with HO at room temperature, a widely used model reaction mimicking the activity of peroxidase in biological catalytic oxidation processes. Driven by hydrophobic interactions, the double-tailed hexavanadate-headed amphiphiles can self-assemble into bilayer vesicles and create hydrophobic domains that segregate the TMB chromogenic substrate. The reaction of TMB with HO takes place at the interface of the hydrophilic and hydrophobic domains, where the reagents also make contact with the catalytic hexavanadate clusters, and it is approximately two times more efficient compared with the reactions carried out with the corresponding unassembled systems. Moreover, the assembled vesicular system possesses affinity for TMB comparable to that of reported noble metal mimic nanomaterials, as well as a higher maximum reaction rate. [ABSTRACT FROM AUTHOR]

Two-dimensional nanomaterials have become a hot research topic, and progress in research on them in the past decade has been substantial. Here we demonstrate a molecule-based bottom-up method to synthesize freestanding polyoxometalatebased nanosheets in two different ways. The trans substitution of ligands with carboxylate functionality promoted the coordination of organically derivatized hexavanadate with zinc ions with preferential directionality, which led to the formation of coordination polymer nanosheets. Characterization with transmission electron microscopy, powder X-ray diffraction, and infrared spectroscopy confirmed the morphology, structural composition, and preferential direction of the nanosheets. The microwave-assisted heating method and solvent addition method were proved to be effective for the preparation of POM-based nanosheet structures. The nanosheets were found to catalyze the aerobic oxidation of propanethiol (n-PrSH) to its corresponding disulfide (PrSSPr) under mild conditions. [ABSTRACT FROM AUTHOR]

The compound (Hql)2[Fe2(cit)2(H2O)2]·4H2O (1) [ql = quinoline, cit4− = C(O−)(CO− 2)(CH2CO− 2)2], prepared by reacting ferric nitrate, sodium citrate and quinoline in a molar ratio of 1:1:1 in aqueous solution, was characterized by density measurements, elementary analysis, i.r., X-ray crystallography and magnetic measurements. The X-ray crystallography results reveal that the molecule (1) consists of a binuclear iron(III) citrate anionic complex [Fe2(cit)2(H2O)2]2− and two protonated quinolines [Hql]+. The anionic complex has a centro-symmetric structure, in which two Fe3+ ions are bridged by two μ2-alkoxo groups of the two deprotonated citrate ligands. The other coordination sites of the two slightly distorted octahedra are completed by all the carboxylate groups of the two cit4− ligands in a monodentate mode, and two coordinated water molecules. Magnetic measurements indicate that the two Fe3+ ions are antiferromagnetically coupled below 200 K. A least-squares fit of variable-temperature (1.5–291 K) molar susceptibility data to a dimer model gave the coupling constant J/k = −6.35(7) K and Landé factor g = 2.052(9), where the spin-only Heisenberg–Dirac–van Vleck Hamiltonian is expressed as H = −2 J S1 S2. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Engineering catalytic sites at the atomic level provides an opportunity to understand the catalyst's active sites, which is vital to the development of improved catalysts. Here we show a reliable and tunable polyoxometalate template-based synthetic strategy to atomically engineer metal doping sites onto metallic 1T-MoS2, using Anderson-type polyoxometalates as precursors. Benefiting from engineering nickel and oxygen atoms, the optimized electrocatalyst shows great enhancement in the hydrogen evolution reaction with a positive onset potential of ~ 0 V and a low overpotential of −46 mV in alkaline electrolyte, comparable to platinum-based catalysts. First-principles calculations reveal co-doping nickel and oxygen into 1T-MoS2 assists the process of water dissociation and hydrogen generation from their intermediate states. This research will expand on the ability to improve the activities of various catalysts by precisely engineering atomic activation sites to achieve significant electronic modulations and improve atomic utilization efficiencies. While heterogeneous catalysts can act as tangible, efficient materials for energy conversion, understanding the active catalytic sites is challenging. Here, authors engineer specific catalytic sites into molybdenum sulfide to improve and elucidate hydrogen evolution electrocatalysis. [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]

Mercury and its compounds are known to be extremely toxic but widely distributed in environment. Although many works have been reported to efficiently detect mercury, development of simple and convenient sensors is still longed for quick analyzing mercury in water. In this work, a nanoscale metal-oxo cluster, (n-Bu4N)2[Mo5NaO13(OCH3)4(NO)], (MLPOM), organically-derivatized from monolacunary Lindqvist-type polyoxomolybdate, is found to specifically react with Hg2+ in methanol/water via structural transformation. The MLPOM methanol solution displays a color change from purple to brown within seconds after being mixed with an aqueous solution containing Hg2+. By comparing the structure of polyoxomolybdate before and after reaction, the color change is revealed to be the essentially structural transformation of MLPOM accelerated by Hg2+. Based on this discovery, MLPOM could be utilized as a colorimetric sensor to sense the existence of Hg2+, and a simple and label-free method is developed to selectively detect aqueous Hg2+. Furthermore, the colorimetric sensor has been applied to indicating mercury contamination in industrial sewage. [ABSTRACT FROM AUTHOR]