PtFe alloy nanostructures enclosed by differently oriented facets, including polyhedrons, concave cubes, and nanocubes, were synthesized through the fine adjustment of specific surfactant−crystal facet bindings. PtFe nanostructures with various alloy compositions were then employed as the counter electrodes (CEs) for the redox reaction of iodide/ tri-iodide (I − /I 3 − ) in dye-sensitized solar cells. Devices with the Pt 9 Fe 1 polyhedrons and Pt 9 Fe 1 concave cubes produced better photovoltaic conversion efficiency (PCE) of 8.01% and 7.63% in comparison to the PCE of 7.24% achieved with Pt CE. The superiority is attributed to the rapid charge transfer, higher limit current, and better electronic conductivity and catalytic activity with respect to the Pt CEs. The photovoltaic and electrochemical results indicated the shape-and composition-dependent activity in the I − /I 3 − redox reaction, which obeys the sequence of polyhedrons > concave cubes > nanocubes and Pt 9 Fe 1 nanostructures > Pt 7 Fe 3 nanostructures. Further theoretical work indicated that the I 3 − reduction activity of the nanosurfaces was in the order of Pt 9 Fe 1 (111) > Pt(111) > Pt 9 Fe 1 (100). The combination of experimental and theoretical work thus clearly demonstrates the shape-and composition-dependence of PtFe nanostructures in terms of the I 3 − reduction activity.

PtCoFe nanowires with different alloying compositions are chemically prepared and acted as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) with Ru(II)-based dyes. Due to their superior − − I 3 reduction activity, PtCoFe nanowires with rich (111) facets enhance the performance of DSSCs. Hence, N719 DSSCs with PtCoFe nanowires, respectively, produce better power conversion efficiency (PCE) of 8.10% for Pt 33 Co 24 Fe 43 nanowire, 8.33% for Pt 74 Co 12 Fe 14 nanowire, and 9.26% for Pt 49 Co 23 Fe 28 nanowire in comparison to the PCE of Pt CE (7.32%). Further, the PRT-22 DSSC with Pt 49 Co 23 Fe 28 nanowire exhibits a maximum PCE of 12.29% with a certificated value of 12.0%, which surpass the previous PCE record of the DSSCs with Ru(II)-based dyes. The photovoltaic and electrochemical results reveal the composition-dependent activity along with a volcano-shaped trend in the I − / − − I 3 redox reaction. Theoretical work on the adsorption energies of I 2 , the desorption energies of I − , and the corresponding absolute energy demonstrates that the − − I 3 reduction activity followed in the order of Pt 49 Co 23 Fe 28 (111) plane > Pt 74 Co 12 Fe 14 (111) plane > Pt 33 Co 24 Fe 43 (111) plane, proving Pt 49 Co 23 Fe 28 nanowire to be a superior cathode material for DSSCs.

Molecular self-assembly, taking advantage of reversible intermolecular interactions, represents an efficient method to prepare ultrathin films exhibiting minimal packing defects. The same protocol seems reasonable to fabricate hybrid monolayers yet typically results in segregated domains. Demonstrated herein is a host–guest concept in which guest molecules are hosted in homogeneously patterned voids at the liquid–solid interface. However, 2D open lattices with low packing densities often suffer poor stability. In this study, the concept is realized by a 2D porous network assembled via 1,3,5-tris­(4-carboxy­phenyl)­benzene (BTB) whose stability is significantly enhanced by hosting spatially matched pentacene or its analogues. The conformal contact between the nearest neighbors optimizes intermolecular interactions. Simulation results of molecular mechanics for a simplified model suggest that the hybrid lattice is about 250 kcal/mol per BTB pore more stable than guests such as coronene and Cu-phthalocyanine.

Constructing two-dimensional (2D), free-standing, nonprecious, and robust electrocatalysts for oxygen evolution reactions (OERs) is of primary importance in the commercial water-splitting technology. Herein, we have constructed a 2D heterostructured NiFe 2 O 4 /NiFe layered double hydroxides (LDH) mixed composite on a low-cost stainless-steel mesh substrate using a lowtemperature one-step wet chemical synthesis method and have also investigated the effect of starting material concentration on the formation of the NiFe 2 O 4 /NiFe LDH mixed composite. The as-prepared NiFe 2 O 4 /NiFe LDH-25 electrocatalyst drives a 100 mA/cm 2 OER with the lowest reported overpotential of 190 mV and a Tafel slope 21.5 mV/dec and drives a stable 100 mA/cm 2 OER process in 1 M KOH. These OER activities are superior to that of the state-of-the-art RuO 2 OER electrocatalyst. The excellent OER activity appears to be due to the synergetic effect of NiFe LDHs and NiFe 2 O 4 . In addition, the vertically aligned heterostructure of the NiFe 2 O 4 /NiFe LDH composite thin sheets provides a large number of active edge sites, directly attached to the highly conducting substrate, which contributes to improving the electronic conductivity of the electrocatalyst. This work provides valuable insight into the design and one-step synthesis of NiFe 2 O 4 /NiFe LDH bimetallic mixed oxide and hydroxide composite thin films with enhanced OER activity and stability as well as deciphering the origin of the OER enhancement by metal oxides and metal hydroxides.

A simple and sensitive biosensor array based on phosphorescence detection that is able to detect oxygen and glucose in human serum, respectively, has been developed. We demonstrate an electrochemical method as a fast, effective, tunable, and versatile means of growing phosphorescence sensing material. This sensing material, crystalline iridium(III)-Zn(II) coordination polymers, namely Ir-Zn(e), was grown on a stainless steel mesh and then doped in a sol-gel matrix. The emission of Ir-Zn(e) was ascribed to a metal-to-ligand charge transfer transition (MLCT). The noteworthy oxygen-sensing properties of Ir-Zn(e) were also evaluated. The optimal oxygen-sensing conditions of Ir-Zn(e) with a deduced K(SV) value of 3.55 were 5 V and 30 °C for 1 hour. Moreover, the short response time (23 s) and the recovery time (21 s) toward oxygen have been measured. The reversibility experiment was carried out for eleven cycles. The resulting >70% recovery of intensity for Ir-Zn(e) on each cycle demonstrated a high degree of reproducibility during the sensing process. The detection limit could be 0.050% for gaseous oxygen. The sensing substrate was subsequently built up under glucose oxidase encapsulated in hydrogel and then immobilized on an egg membrane by the layer-by-layer method. Once the glucose solution was injected into this array, oxygen content depleted simultaneously with a concomitant increase in the phosphorescence of coordination polymers. The linear dynamic range for the determination of glucose was 0.1-6.0 mM, the correlation coefficient (R(2)) was 0.9940 (y = 0.75 [glucose] + 0.539), and the response time was less than 120 s. The minimum detectable concentration for glucose was calculated to be 0.05 mM from three times signal to noise. The photophysical properties of the sensing material and the effects of buffer concentration, pH, interference, matrix effect, temperature, and the stability of the biosensor array have also been studied in detail. The biosensor array was successfully applied to the determination of glucose in human serum.

Four iridium(III)-containing coordination polymers 1-4 using Ir(ppy)(2)(H(2)dcbpy)PF(6) (L-H(2), ppy = 2-phenylpyridine, H(2)dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) as the bridging ligand, [ZnL(2)]·3DMF·5H(2)O (1), [CdL(2)(H(2)O)(2)]·3DMF·6H(2)O (2), [CoL(2)(H(2)O)(2)]·2DMF·8H(2)O (3) and [NiL(2)(H(2)O)(2)]·3DMF·6H(2)O (4), have been synthesized and structurally characterized. The emissions from 1-4 are ascribed to a metal-to-ligand charge transfer transition (MLCT). The absolute emission quantum yields for 1-4 in single crystals were measured in air to be 0.274, 0.193, 0.001 and 0.002, respectively. The noteworthy oxygen-sensing properties of 1-4 as well as L-H(2) in a single crystal were also evaluated. The Stern-Volmer quenching constant, K(SV) values, of 1-4 and L-H(2) can be deduced to be 0.834, 2.820, 1.328, 1.111 and 2.476, respectively. The results show promising K(SV) values (e.g.2) that are competitive or even larger than those of many known Ir-complexes. Moreover, the short response time (e.g. compound 2) and recovery times toward oxygen of 1-4 have been measured in their single crystal forms. The reversibility experiments for 1-4 were carried out for seven repeated cycles. As a result, >75% recovery of intensity for 1 and 2 on each cycle demonstrates a high degree of reproducibility during the sensing process. It should be noted that iridium(III)-containing coordination polymers with high emission intensity and notable oxygen sensing properties are obscure, especially in the single crystal form. This, in combination with its fine reversibility, leads to success in single crystal oxygen recognition based on photoluminescence imaging. The detection limit could be 0.50% for gaseous oxygen. Moreover, the temperature effect of compound 2 in a single crystal upon application as an oxygen sensor was expected.

A new coordination polymer, [Zn(HBTC)(BPE)0.5(H2O)]n·nH2O (1) with an extended 1D ladderlike metal-organic framework (MOF) has been synthesized and structural characterized by single-crystal X-ray diffraction method. Structural determination reveals that, in compound 1, the Zn(II) ion is four-coordinated in a distorted tetrahedral geometry, bonded to one nitrogen atom from one BPE ligand, and three oxygen atoms from two monodentate carboxylate groups of two HBTC(2-) ligands and one coordinated water molecule. The HBTC(2-) acts as a bridging ligand with a bis-monodentate coordination mode, connecting the Zn(II) ions to form a one-dimensional (1D) [Zn(HBTC)] chain. Two 1D chains are then interlinked via the connectivity between the Zn(II) ions and anti-BPE liagnds to complete the 1D ladderlike MOF. Adjacent 1D Ladders are further extended to a 2D hydrogen-bonded layered network through the intermolecular O-H · · · O hydrogen bond between the carboxylic group and carboxylate group of interladder HBTC(2-) ligand. Adjacent 2D layers are then packed orderly in an ABAB-type array via the intermolecular interactions of combined π-π interaction and O-H · · · O hydrogen bonds to form a 3D supramolecular architecture exhibiting 1D channels intercalated with guest water molecules. The reversible solid-state structural transformation between crystalline 1 with 1D ladderlike framework and its dehydrated powder 2, [Zn(HBTC)(BPE)0.5]n, with 2D framework via the displacement of coordinated water molecule to HBTC(2-) ligand, by thermal de/rehydrated processes has been verified by PXRD measurements. The emission of 1 and 2 is ascribed to a ligand-based transition.

A new coordination polymer, [Zn(dpe)(bdc)]·4H(2)O (ZndB; dpe=1,2-bis(4-pyridyl)ethane, bdc(2-)=dianion of benzenedicarboxylic acid), which possesses a 3D metal-organic framework (MOF) has been synthesized and structurally characterized. This 3D MOF is constructed by the assembly of helical channels filled with guest water molecules in both inner and outer regions of the channel. The resulting network also creates a 2D water layer containing hydrogen-bonded (H(2)O)(16) rings as the basic building units. Thermogravimetric and powder X-ray diffraction measurements of ZndB revealed a two-step weight loss of water molecules with a reversible water adsorption/desorption process in the inner channel for the first stage, and irreversible water desorption in the outer channel for the second stage. This spongelike property is manifested by the excimer emission originating from interaction between dpe (π*) and the other dpe (π) of the proximal helical channel, which is highly sensitive to the environmental perturbation. Powder X-ray analyses reveal that the dehydration process induces the readjustment of dpe π-π stacking distance/orientation, which results in dramatic luminescence changes from dim pale blue (λ(em)≈470 nm) upon hydration to bright white-light generation (broad, λ(em)≈500-550 nm) upon water depletion, accompanied by a ≈100-fold increase in the emission intensity.