Construction of Pt/Ni/NiFe2O4/C nanocomposite with one dimensional hollow structure for portable glucose sensing application.

Designing portable electrochemical sensors combined with highly efficient glucose oxidation electrodes offers a significant opportunity for convenient glucose detection. In this report, we present the design and preparation of platinum deposited Ni/NiFe2O4/Carbon composite (Pt/Ni/NiFe2O4/C) derived from Ni/Fe metal-organic frameworks (MOFs) followed by Pt deposition. Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electron microscopy (EM) were utilized to analyze the crystal structure, morphology, and chemical composition of the resulting materials. The glucose sensing capabilities of the optimal Pt/Ni/NiFe2O4/C-3 were assessed using amperometry methods on a smartphone-based portable device. Acting as a nonenzymatic glucose sensor, the Pt/Ni/NiFe2O4/C-3 electrode demonstrated notable sensitivity and a low limit of detection for glucose. The portable sensor exhibits high sensitivities of 131.88 µM mM cm-2 at low glucose concentration (3-500 µM) and 29.52 µA mM cm-2 at high glucose concentration (700-4000 µM), achieving a low detection limit of 1.1 µM (S/N = 3). The sensor also demonstrates enhanced selectivity and stability for detecting glucose. Furthermore, the portable sensor exhibits a clear step-ampere response in the detection of serum samples with satisfactory recovery ranging from 99.30 to 101.32%. This suggests the significant potential of portable glucose sensing applications.

Fabricating BiOCl Nanoflake/FeOCl Nanospindle Heterostructures for Efficient Visible-Light Photocatalysis.

Fabricating heterostructures with abundant interfaces and delicate nanoarchitectures is an attractive approach for optimizing photocatalysts. Herein, we report the facile synthesis of BiOCl nanoflake/FeOCl nanospindle heterostructures through a solution chemistry method at room temperature. Characterizations, including XRD, SEM, TEM, EDS, and XPS, were employed to investigate the synthesized materials. The results demonstrate that the in situ reaction between the Bi precursors and the surface Cl- of FeOCl enabled the bounded nucleation and growth of BiOCl on the surface of FeOCl nanospindles. Stable interfacial structures were established between BiOCl nanoflakes and FeOCl nanospindles using Cl- as the bridge. Regulating the Bi-to-Fe ratios allowed for the optimization of the BiOCl/FeOCl interface, thereby facilitating the separation of photogenerated carriers and accelerating the photocatalytic degradation of RhB. The BiOCl/FeOCl heterostructures with an optimal composition of 15% BiOCl exhibited ~90 times higher visible-light photocatalytic activity than FeOCl. Based on an analysis of the band structures and reactive oxygen species, we propose an S-scheme mechanism to elucidate the significantly enhanced photocatalytic performance observed in the BiOCl/FeOCl heterostructures.

Electrochemical sensors based on platinum-coated MOF-derived nickel-/N-doped carbon nanotubes (Pt/Ni/NCNTs) for sensitive nitrite detection.

As excess nitrite has a serious threat to the human health and environment, constructing novel electrochemical sensors for sensitive nitrite detection is of great importance. In this report, platinum nanoparticles were deposited on nickel-/N-doped carbon nanotubes, which were obtained through a self-catalytically grown process with Ni-MOF as precursors. The as-prepared Pt/Ni/NCNTs were applied as amperometric sensors and presented superior sensing properties for nitrite detection. Benefiting from the synergy of Pt and Ni/NCNTs, Pt/Ni/NCNTs displayed much wider detection ranges (0.5-40 mM and 40-110 mM) for nitrite sensing. The sensitivity is 276.92 µA mM-1 cm-2 and 224.39 µA mM-1 cm-2, respectively. The detection limit is 0.17 µM. The Pt/Ni/NCNTs sensors also showed good feasibility for nitrite sensing in real samples (milk and peach juice) analysis. The active Pt/Ni/NCNTs composites and facile fabrication technique may provide useful strategies to develop other sensitive nitrite sensors.

Fabrication of an anion exchange membrane with textured structure for enhanced performance of direct borohydride fuel cells.

Developing electrolyte membranes with a simple preparation process and high performance is a top priority for the commercialization of fuel cells. Inspired by solar cell texturing to improve its conversion efficiency, this study prepares a textured membrane by increasing the roughness of a glass plate. The structures of the textured membrane and the flat membrane are characterized and compared. The membranes are assembled in fuel cells for performance testing. The surface area of the textured membrane is 1.27 times that of the flat membrane, which increases the size of the three-phase boundary in fuel cells. The maximum power density of the fuel cell using the textured membrane is 1.17 times of the cell using the flat membrane at 60 °C. The excellent performance of the cell using the textured membrane profit from the enlargement of the three-phase boundary. This work offers a simple way to develop outstanding-performance membranes by changing their surface roughness.

Highly Dispersed Vanadia Anchored on Protonated g-C3N4 as an Efficient and Selective Catalyst for the Hydroxylation of Benzene into Phenol.

The direct hydroxylation of benzene is a green and economical-efficient alternative to the existing cumene process for phenol production. However, the undesired phenol selectivity at high benzene conversion hinders its wide application. Here, we develop a one-pot synthesis of protonated g-C3N4 supporting vanadia catalysts (V-pg-C3N4) for the efficient and selective hydroxylation of benzene. Characterizations suggest that protonating g-C3N4 in diluted HCl can boost the generation of amino groups (NH/NH2) without changing the bulk structure. The content of surface amino groups, which determines the dispersion of vanadia, can be easily regulated by the amount of HCl added in the preparation. Increasing the content of surface amino groups benefits the dispersion of vanadia, which eventually leads to improved H2O2 activation and benzene hydroxylation. The optimal catalyst, V-pg-C3N4-0.46, achieves 60% benzene conversion and 99.7% phenol selectivity at 60 oC with H2O2 as the oxidant.

Encapsulating Mn3O4 Nanorods in a Shell of SiO2 Nanobubbles for Confined Fenton-Type Catalysis.

Core-shell structured nanomaterials with delicate architectures have attracted considerable attention for realizing multifunctional responses and harnessing multiple interfaces for enhanced functionalities. Here, we report a controllable synthesis of core-shell structured Mn3O4@SiO2NB nanomaterials consisting of Mn3O4 nanorods covered with a shell of SiO2 nanobubbles. A series of Mn3O4@SiO2NB catalysts with tunable secondary structures can be synthesized by simply tuning the feeding ratio and the modification conditions. The as-synthesized Mn3O4@SiO2NB catalysts exhibit excellent catalytic performance in the degradation of methylene blue (MB) because the Fenton-type reaction between Mn3O4 and H2O2 is confined in an MB-rich environment created by the SiO2 nanobubble shell. The confined Fenton-type catalysis maximizes the contact of MB molecules with the reactive oxygen species and significantly promotes the degradation efficiency of MB. Under optimal conditions, Mn3O4@SiO2NB-0.4 can reach a degradation efficiency of 92% at room temperature and neutral pH within 12 min, which outperforms most reported Mn-based catalysts.

Diaqua-bis[5-(5-carboxy-2-pyridyl)tetra-zolato-κN,N]cadmium(II) dihydrate.

In the title complex, [Cd(C(7)H(4)N(5)O(2))(2)(H(2)O)(2)]·2H(2)O, the water-coordinated Cd(II) atom ( symmetry) is coordinated by four N atoms from two symmetry-related 3-carboxy-pyidyl-6-tetra-zolato ligands, forming a distorted octa-hedral complex. The uncoordinated water mol-ecules connect the mononuclear units into a layer structure through O-H⋯N and O-H⋯O hydrogen bonds; similar hydrogen bonds between coordinated water mol-ecules and anionic groups result in a three-dimensional structure.

Bis[µ-5-(5-carboxyl-ato-3-pyrid-yl)tetra-zolato-κN,N:N]bis-[triaqua-zinc(II)].

In the title complex, [Zn(2)(C(7)H(3)N(5)O(2))(2)(H(2)O)(6)], the 5-(5-carboxyl-ato-3-pyrid-yl)tetra-zolate ligand chelates the Zn(II) center through one pyridyl N and one tetra-zolate N atom, and uses another N atom to bridge to the second Zn atom, forming a centrosymmetric dinuclear unit. Three coordinated water mol-ecules complete the distorted octa-hedral geometry of the Zn(II) atom. O-H⋯O and O-H⋯N hydrogen bonds involving the coordinated water mol-ecules, tetra-zolate N atoms and the carboxyl-ate group result in a three-dimensional structure.

Mimicking the Self-Organized Microstructure of Tooth Enamel.

Under near-physiological pH, temperature, and ionic strength, amelogenin (Amel) accelerates hydroxyapatite (HAP) nucleation kinetics, decreasing the induction time in a concentration-dependent manner. Hierarchically organized apatite microstructures are achieved by self-assembly involving nucleated nanocrystallites and Amel oligomers and nanospheres at low supersaturations and protein concentrations in a slow and well-controlled constant composition (CC) system. The CC method allows the capture of an intermediate structure, the nanorod, following the formation of the critical nuclei at the earliest nucleation stages of calcium phosphate crystallization. The nanorod building blocks form spontaneously by synergistic interactions between flexible Amel protein assemblies and rigid calcium phosphate nanocrystallites. These intermediate structures further assemble by a self-epitaxial growth mechanism to form the final hierarchically organized microstructures that are compositionally and morphologically similar to natural enamel. This in vitro observation provides direct evidence that Amel promotes apatite crystallization and organization. We interpret our observations to propose that in vivo Amel may maximally exert an influence on the structural control of developing enamel crystals at the earliest nucleation stages.