Search

In this study, a new cobalt-based metal–organic framework (JLNU-500), [Co2(OH)(PBA)(AIP)]·3DMA·0.75H2O (4-(pyridin-4-yl) benzoic acid (HPBA), 5-aminoisophthalic acid (H2AIP) and N,N-dimethylacetamide (DMA)), was fabricated using a solvothermal method. JLNU-500 has 3D network architecture with 1D nanopore channels. The prepared JLNU-500 can activate peroxymonosulfate (PMS) for Rhodamine B (RhB) dye decolorization. Interestingly, catalyst JLNU-500 exhibited high efficiency for PMS activation, and nearly 100% (above 99.8%) removal of RhB with a high concentration (50.0 mg L−1, 100 mL) was achieved within 6 min. The reaction rate constant of the JLNU-500/PMS system was 1.02 min−1 calculated based on the pseudo-first-order kinetics, which is higher than that of the other reported catalysts. Furthermore, the factors, which could influence PMS activation were also investigated, such as PMS dosage, catalyst dosage, pollutant RhB concentration, reaction temperature and solution pH. More importantly, the radical trapping experiments ferreted out that sulfate (SO4˙−) and hydroxyl (˙OH) radicals were the dominating oxidants in the removal of RhB. Moreover, the possible degradation mechanism was elucidated. This study provides new prospects for fabricating new MOFs that can potentially be employed for high-efficiency catalytic oxidation as heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Elucidations on the structure–activity correlations of non-Pt coordination polymer (CP)-based photocatalysts are highly significant for both the enhancement in catalytic activity and large-scale industrial applications of sustainable hydrogen from water splitting. Herein, three isostructural [Cu(HL)2(R-BDC)]n (denoted as Cu-CP-R, HL = 4′-(4-hydroxyphenyl)-4,2′:6′,4′′-terpyridine, R-BDC = 2-R-1,4-benzenedicarboxylate, R = NO2, OH and Br) CPs were solvothermally synthesized by varying the substituents attached to benzenedicarboxylate, which together with two previously reported analogues (R = NH2 and H) were used as photocatalysts to systematically explore the substitution effect on the hydrogen evolution activity. These five CPs feature isomorphic layered motifs with axially elongated CuII octahedra extended alternately by ditopic HL and R-BDC2− connectors, in which R behaves structurally as a non-coordinate group. The hydrogen production rate over the Cu-CP-R photocatalysts increased from 0.21 to 2.34 mmol g−1 h−1, which followed the order of –NH2 > –NO2 > –H > –OH > –Br. Furthermore, the combined experimental and theoretical investigations reveal that the free R moiety significantly dominates the photocatalytic activity by shifting the d states of the CuII ion towards the Fermi level, controlling the potential of the conduction band and quickening the charge transfer ability. These important findings can provide informative hints for the design of high-performance, earth-abundant non-noble metal CP-based semi-conductive photocatalysts. [ABSTRACT FROM AUTHOR]

Two copper(ii)-based layered complexes with or without the amino group, [Cu(HL)2(NH2-BDC)]n (1) and [Cu(HL)2(BDC)]n (2) (HL = 4′-(4-hydroxyphenyl)-4,2′:6′,4′′-terpyridine, NH2-H2BDC = 2-amino-1,4-benzenedicarboxylic acid and H2BDC = 1,4-benzenedicarboxylic acid), were solvothermally synthesized and used as photocatalysts to accelerate hydrogen production from water splitting. The amino group modified 1 has exhibited greatly enhanced photocatalytic activity with a hydrogen production rate of 2.34 mmol g−1 h−1 under visible light irradiation, which is almost double that of 2. Density functional theory calculations, electrochemical impedance spectroscopy and transient photocurrent tests demonstrate that the higher catalytic activity of 1 than 2 is a result of the enriched electron density around the CuII center by the amino group, which facilitates the charge transfer from the conduction band to the water molecule. [ABSTRACT FROM AUTHOR]

All-metal electride molecules, CuAg@Ca7M (M = Be, Mg and Ca), have been designed and researched in theory for the first time. In these molecules, a pull–push electron relay occurs. Unusually, the all-metal polyanions of fourfold negatively charged [Cu–Ag–Be/Mg]4− and [Cu–Ag]4− with 4 extra electrons gained from Ca atoms push the remaining valence electrons of the Ca atoms forming the multi-excess electrons (Ne = 10/12). Therefore, these molecules can be described as salt-like [(Ca2+)7(CuAgM)4−] + 10e− (M = Be and Mg) and [(Ca2+)8(CuAg)4−] + 12e−. In these salt-like molecules, there are extraordinary covalent bonding modes, which include 2c–2e/3c–2e σ-bonding in the polyanions and the Ca2+ cations sharing the diffuse multi-excess electrons. For an intriguing nonlinear optical (NLO) response, these all-metal electride molecules display large electronic first hyperpolarizabilities (β0), thus a new class of NLO molecules, all-metal electride NLO molecules, emerge. Moreover, it is also found that manipulating the atomic number and position of M is a new strategy to enhance β0. As a result, CuAg@Ca7Mg(1) exhibits a considerable β0 (1.43 × 104 au), which is 16 times the β0 sum of two isolated CuAg and Ca7Mg(1) subunits, and this deeply reveals the fundamental origin of the considerable β0, namely, the multi-excess electrons generated by the subunit interaction. These all-metal electride molecules have the infrared (IR) transparent region of 1.3–6 μm, and hence are new IR NLO molecules. In addition the electronic contribution, β0, the large effects of vibrations on the static first hyperpolarizabilities of these all-metal electride molecules are also estimated. Thus, this study opens the new research field of all-metal electride IR NLO molecules. [ABSTRACT FROM AUTHOR]

Novel cup–saucer–cage-shaped sandwich electride molecules calix[4]pyrrole…K3O+…e@CnFn−, (n = 8, 10, 14, 20, and 36) with an excess electron protected inside the CnFn cage are constructed theoretically. In the sandwich structures, the below calix[4]pyrrole cup pushes the valence electron of the sandwiched superalkali atom K3O saucer, forming an excess electron, which is further pulled and protected inside the above CnFn cage, thus an electron-transfer relay occurs. In particular, owing to the unusual electron transfer, an unusual and fortunate phenomenon is discovered that increasing the CnFn cage size enhances not only the nonlinear optical response (β0), but also the electron stability (VIP). Thus, a new strategy of simultaneously enhancing β0 and VIP values is found for the first time, namely by increasing the CnFn cage size in novel cup–saucer–cage-shaped sandwich electride molecules, with the excess electron protected inside the cage. [ABSTRACT FROM AUTHOR]