Intercalated and Surface-Adsorbed Phosphate Anions in NiFe Layered Double-Hydroxide Catalysts Synergistically Enhancing Oxygen Evolution Reaction Activity.

The oxygen evolution reaction (OER), a crucial semireaction in water electrolysis and rechargeable metal-air batteries, is vital for carbon neutrality. Hindered by a slow proton-coupled electron transfer, an efficient catalyst activating the formation of an O-H bond is essential. Here, we proposed a straightforward one-step hydrothermal procedure for fabricating PO43--modified NiFe layered double-hydroxide (NiFe LDH) catalysts and investigated the role of PO43- anions in enhancing OER. Phosphate amounts can efficiently regulate LDH morphology, crystallinity, composition, and electronic configuration. The optimized sample showed a low overpotential of 267 mV at 10 mA cm-2. Density functional theory calculations revealed that intercalated and surface-adsorbed PO43- anions in NiFe LDH reduced the Gibbs free energy in the rate-determining step of *OOH formation, balancing oxygen-containing intermediate adsorption/dissociation and promoting the OER. Intercalated phosphate ions accelerated precatalyst dehydrogenation kinetics, leading to a rapid reconstruction into active NiFe oxyhydroxide species. Surface-adsorbed PO43- interacted favorably with adsorbed *OOH on the active Ni sites, stabilizing *OOH. Overall, the synergistic effects of intercalated and surface-adsorbed PO43- anions significantly contributed to enhanced OER activity. Achieving optimal catalytic activity requires a delicate equilibrium between thermodynamic and kinetic factors by meticulously regulating the quantity of introduced PO43- ions. This endeavor will facilitate a deeper comprehension of the influence of anions in electrocatalysis for OER.

Phase-Selective Synthesis of Cobalt Sulfide Heterostructure Catalysts as Efficient Counter Electrodes in Dye-Sensitized Solar Cells.

Developing a cost-saving, high-efficiency, and simple synthesis of counter electrode (CE) material to replace pricy Pt for dye-sensitized solar cells (DSSCs) has become a research hotspot. Owing to the electronic coupling effects between various components, semiconductor heterostructures can significantly enhance the catalytic performance and endurance of counter electrodes. However, the strategy to controllably synthesize the same element in several phase heterostructures used as the CE in DSSCs is still absent. Here, we fabricate well-defined CoS2 /CoS heterostructures and use them as CE catalysts in DSSCs. The as-designed CoS2 /CoS heterostructures display high catalytic performance and endurance for the triiodide reduction in DSSCs thanks to the combined and synergistic effects. As a result, a DSSC with CoS2 /CoS achieves a high energy conversion with an efficiency of 9.47 % under standard simulated solar radiation, surpassing that of pristine Pt-based CE (9.20 %). Besides, the CoS2 /CoS heterostructures possess a quick activity initiation process and extended stability, broadening their potential applications in various areas. Therefore, our proposed synthetic approach could offer new insights for synthesizing functional heterostructure materials with improved catalytic activities in DSSCs.

Metal-organic frameworks constructed from versatile [WS4Cu(x)](x-2) units: micropores in highly interpenetrated systems.

Five metal-organic frameworks (MOFs) formed by [WS(4)Cu(x)](x-2) secondary building units (SBUs) and multi-pyridyl ligands are presented. The [WS(4)Cu(x)](x-2) SBUs function as network vertexes showing various geometries and connectivities. Compound 1 contains one-dimensional channels formed in fourfold interpenetrating diamondoid networks with a hexanuclear [WS(4)Cu(5)](3+) unit as SBU, which shows square-pyramidal geometry and acts as a tetrahedral node. Compound 2 contains brick-wall-like layer also with a hexanuclear [WS(4)Cu(5)](3+) unit as SBU. The [WS(4)Cu(5)](3+) unit in 2 is a new type of [WS(4)Cu(x)](x-2) cluster unit in which the five Cu(+) ions are in one plane with the W atom, forming a planar unit. Compound 3 shows a nanotubular structure with a pentanuclear [WS(4)Cu(4)](2+) unit as SBU, which is saddle-shaped and acts as a tetrahedral node. Compound 4 contains large cages formed between two interpenetrated (10,3)-a networks also with a pentanuclear [WS(4)Cu(4)](2+) unit acting as a triangular node. The [WS(4)Cu(4)](2+) unit in 4 is isomeric to that in 3 and first observed in a MOF. Compound 5 contains zigzag chains with a tetrahedral [WS(4)Cu(3)](+) unit as SBU, which acts as a V-shaped connector. The influence of synthesis conditions including temperature, ligand, anions of Cu(I) salts, and the ratio of [NH(4)](2)WS(4) to Cu(I) salt on the formation of these [WS(4)Cu(x)](x-2)-based MOFs were also studied. Porous MOF 3 is stable upon removal and exchange of the solvent guests, and when accommodating different solvent molecules, it exhibits specific colors depending on the polarity of incorporated solvent, that is, it shows a rare solvatochromic effect and has interesting prospects in sensing applications.

Highly efficient and self-supported 3D carbon nanotube composite electrode for enhanced oxygen reduction reaction.

A binder-free and self-supported 3D carbon nanotube composite electrode with NiFe nanoalloys, N doping and Fe/Ni-N x -C structures was fabricated by a facile method. The strong synergistic effects of multi-components and the unique structural merits of the optimized sample endowed it outstanding oxygen reduction reaction activity with an onset potential of 1.048 V vs. RHE in 0.1 M KOH solution.

Novel mesoporous Ag@SiO2 nanospheres as a heterogeneous catalyst with superior catalytic performance for hydrogenation of aromatic nitro compounds.

Mesoporous core-shell structure Ag@SiO2 nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction. The prepared catalyst shows superior catalytic performance for hydrogenation of nitro compounds with 100% conversion and selectivity without any by-products, which also indicates good recycling performance for several times use.

Three new heterothiometallic cluster polymers with fascinating topologies.

Three new heterothiometallic cluster polymers with fascinating topologies have been synthesized by the self-assembly of preformed heterothiometallic cluster monomers and appropriate ligands. Reaction of the monomeric cubic-shaped cluster [Et(4)N](3)[MoOS(3)Cu(3)I(4)] with the D(2h) symmetry rigid bidentate 4,4'-bipy (4,4'-bipyridine) gave a two-dimensional (2D) layer compound [Mo(2)O(2)S(6)Cu(6)I(2)(4,4'-bipy)(3)(H(2)O)](n) (1); the assembly of pentanuclear cluster monomer [Et(4)N](4)[WS(4)Cu(4)I(6)] with C(s)-symmetrical bpe (1,2-bis(4-pyridyl)ethane) afforded a 2D layer compound [WS(4)Cu(4)I(2)(bpe)(3)(H(2)O)](n) (2), and the assembly of heptanuclear cluster monomer [Et(4)N](4)[WS(4)Cu(6)I(8)] with D(3h) symmetry trigonal planar ligand timtz (2, 4, 6-tri(1H-imidazol-1-yl)-1, 3, 5-triazine) afforded a three-dimensional (3D) compound [WS(4)Cu(6)I(4)(timtz)(8/3)(H(2)O)(12)](n) (3). X-ray crystallographic analysis reveals that 1 crystallizes in trigonal space group R3c with 2D 3(6)-hxl net which is the first heterothiometallic superamolecular structure based on a twin cubic-shaped cluster monomer and also the first example of 4,4'-bipy-connected compound of this net. 2 crystallizes in tetragonal space group P4(2) with distorted 2D 3(6)-hxl net which is the first flexible-ligand-based compound of this topology; while 3 has a 3D net with the high symmetry of cubic space group I43d, and has a novel alpha-C(3)N(4) topology, which is the maximum symmetry for this net topology. The gas sorption isotherm was measured for 3 to exhibit type-III sorption behavior.

Hydrothermal synthesis, structures, and physical properties of four new flexible multicarboxylate ligands-based compounds.

Four new compounds of partially or wholly deprotonated 5,5'-(1,4-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L1) and 5,5'-(1,3-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L2), namely {[Co(L1)0.5] x (H2O)2}n (1), {[Mn(L1)0.5] x (H2O)2}n (2), {[Cu(H2L1)](mu2-bipy)}n (bipy = 4, 4'-bipyridyl) (3), and {[Zn2(L2)] x H2O}n (4) were synthesized in the presence or absence of auxiliary bipy ligand. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Compounds 1 and 2 are isostructural and possess three-dimensional (3D) networks. In compound 3, multicarboxylate ligands and bipy ligands link Cu centers to generate a two-dimensional (2D) sheet structure which is further connected by intermolecular hydrogen bonds to form a 3D supramolecular structure. In compound 4, the Zn centers are connected by L2(4-) anions to generate a 3D framework. Magnetic susceptibility measurements indicate that compounds 1 and 2 exhibit antiferromagnetic coupling between adjacent Co(II) ions and Mn(II) ions. The photoluminescent properties of the free 4L1 and H4L2 ligands and compound 4 have been studied in the solid state at room temperature. Both ligands and compound 4 exhibit strong violet emissions. Compared with the fluorescent emission of the ligand, the emission of 4 is red-shifted and enhanced.

Syntheses, structures, and properties of six cobalt(II) complexes based on a tripodal tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine ligand.

Six new cobalt(ii) metal-organic frameworks, {[Co1.5(TTPA)(BTC)(H2O)]2·13H2O}n (1), [Co(TTPA)(PA)]n (2), {[Co(TTPA)(BDA)0.5(NO3)]·3H2O}n (3), {[Co2(TTPA)3(OBA)2(H2O)3]·2CH3CN·4H2O}n (4), {[Co(TTPA)(AIP)(H2O)]·2H2O}n (5), and {[Co(TTPA)(MIP)(H2O)]·2H2O}n (6), have been prepared by the self-assembly of a tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine (TTPA) ligand with different aromatic carboxylate auxiliary ligands (H3BTC = 1,3,5-benzenetricarboxylic acid, H2PA = phthalic acid, H2BDA = (1,1'-biphenyl)-4,4'-dicarboxylic acid, H2OBA = 4,4'-oxydibenzoic acid, H2AIP = 5-aminoisophthalic acid, H2MIP = 5-methylisophthalic acid) and cobalt salts. Their structures have been characterized by infrared spectroscopy, elemental analysis, single crystal X-ray analysis, and powder X-ray diffraction. Complex 1 is an unusual 4-nodal (3,3,4,8)-connected three-dimensional (3D) new topological net with the point symbol of (4·6·8)4(4(4)·6(7)·8(15)·10(2))(6(2)·8(4)). Complex 2 has a 2-fold interpenetrating 3D dia framework. Complex 3 displays a rare binodal (3,4)-connected 4-fold interpenetrating 3D architecture with a fsc-3,4-C2/c topology with the point symbol of (4·6·8)(4·6(2)·8(3)). Complex 4 shows two distinct two-dimensional (2D) layers with hcb topologies, which are further packed into a 3D structure by O-HO hydrogen bonding interactions. Both complexes 5 and 6 feature similar 2D sheets with sql topologies, which can be further packed into a 3D structure by O-HO hydrogen bonding interactions. Moreover, the thermal stability and UV-visible spectra of these complexes are also discussed in detail. Meanwhile, the variable-temperature magnetic susceptibility measurement of complex 1 reveals antiferromagnetic interactions between Co(ii) ions.

The rational synthesis of (10,3)-type MOFs based on tetranuclear [W(Mo)OS3Cu3]+ secondary building units.

The self-assembly reaction of the preformed clusters with two extended linear and trigonal rigid ligands as organic linkers afforded two 2D and 3D Mo(W)/Cu/S-based cluster polymers. They show unprecedented structure types in Mo(W)/S/Cu chemistry and exhibit strong third-order nonlinear optical properties.

Unprecedented NaI-CuII-LnIII heterometallic coordination polymers based on 3,5-pyrazoledicarboxylate with both infinite cationic and anionic chains.

The self-assembly of 3,5-pyrazoledicarboxylic acid (H3pdc) and metal salts under hydrothermal conditions leads to the formation of a series of novel NaI-CuII-LnIII heterometallic coordination polymers, [[Na(H2O)4]2[Cu(pdc)2Ln(H2O)5]2 x 3H2O]n [Ln = La (1); Sm (2); Pr (3); Nd (4) and pdc3- = 3,5-pyrazoledicarboxylate]. X-Ray structure analyses show that these complexes all exhibit pairs of infinite, unexpected, cationic and anionic chains. It is the first successful attempt to construct unprecedented NaI-CuII-LnIII heterometallic coordination polymers with both infinite cationic and anionic chains. These four complexes show homologous thermal stabilities. The different magnetic properties of are also been reported in this paper.

Syntheses, structures, photoluminescence, and magnetic properties of phenanthrene-based carboxylic acid coordination polymers.

Four new coordination complexes, M2(Htmopa)4(H2O)4 (M = Zn2+ (1), Mn2+ (2), (M(Htmopa)2(H2O)2)n (M = Ni2+ (3), Co2+ (4)), have been synthesized by the hydrothermal reaction of Htmopa (Htmopa = 2,3,6,7-tetramethoxyphenanthrene-9-carboxylic acid) with different transition metals at a suitable temperature. Single-crystal determinations revealed that 1 and 2 are isostructural and possess a dinuclear subunit, each connected into 3D networks by hydrogen bonds and C-H...pi interactions. 3 and 4 are also isostructural: the metal ions are bridged through water molecules and carboxylate oxygen atoms to form 1D wavelike double chains, and these double chains are further extended to a 3D network via hydrogen bonds and C-H...pi interactions. The photoluminescent properties of the free Htmopa ligand and its complexes have been studied in the solid state at room temperature. Both Htmopa and 1 exhibit strong blue emissions. Magnetic susceptibility measurements indicate that 2 and 3 exhibit antiferromagnetic coupling, whereas 4 shows a ferromagnetic coupling and exhibits a single-ion behavior of the Co II ion at a higher temperature range.

Porous nonlinear-optical material based on a twin-nest-shaped heterothiometallic cluster: {[NH(4)][W(2)O(2)S(6)Cu(6)I(3)(4,4'-bipy)(4)].5H(2)O}n.

A novel 3D porous coordination complex based on a twin-nest-shaped heterothiometallic cluster has been synthesized and characterized. The complex shows an unprecedented structure type and interesting nonlinear-optical properties. Its gas sorption property was studied and shown to be comparable to that of previously reported metal-organic frameworks.