Cu–Pd Alloy Nanoparticles on Carbon Paper as a Self-Supporting Electrode for Glucose Sensing

Nanomaterials based on metals and their alloys have been paid increasing attention due to their adjustable morphology, high stability and excellent catalytic activity. In this work, Fritillaria cirrhosa-like Cu–Pd alloy nanoparticles were grown on carbon paper (Cu–Pd/CP) by one-step electrodeposition, serving as a self-supporting electrode to catalyze glucose oxidation. The morphological and structural characterizations of the Cu–Pd alloy were performed using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results showed that Fritillaria cirrhosa-like Cu–Pd alloy nanoparticles with a size of about 600 nm were synthesized and uniformly distributed on CP. The 3D network structure composed of CP with good conductivity and Cu–Pd alloy nanoparticles with unique morphology greatly increased the specific surface area and conductivity of the material, which is beneficial to the electrocatalytic oxidation of glucose. As a self-supporting electrode, the prepared Cu–Pd/CP presented excellent electrocatalytic activity toward glucose oxidation with a wide linear range (0.003–10 mM), high sensitivity (2589 μA mM–1 cm–2), and low detection limit (1.3 μM). The proposed sensor has been successfully applied to the determination of glucose in real human serum samples, indicating that Cu–Pd/CP is a promising candidate for nonenzymatic glucose sensing

Cytotoxic tremulanes and 5,6-secotremulanes, four new sesquiterpenoids from a plant-associated fungus X1-2

<p>Two new tremulanes and two new 5,6-secotremulanes, davotremulanes A-D <b>1</b>–<b>4</b>, along with four known compounds <b>5</b>–<b>8</b>, were isolated from the culture extract of X1-2, an unidentified plant-associated fungus, which was isolated from the endangered plant, <i>Davidia involucrate</i> Baill. in Shennongjia District. The structures of new compounds <b>1</b>–<b>4</b> were established on the basis of extensive spectroscopic analysis. Compounds <b>1</b>–<b>8</b> were evaluated for cytotoxic activity to four cancer cell lines, and compounds <b>1</b>, <b>2</b> and <b>5</b> displayed selectively moderate activities to A549 cell line with IC₅₀ at 15.3, 25.2, 35.2 μg/mL.</p

Atomically Dispersed FeN₂ at Silica Interfaces Coupled with Rich Nitrogen Doping-Hollow Carbon Nanospheres as Excellent Oxygen Reduction Reaction Catalysts

A SiO2-assisted strategy is a promising approach to prepare high-performance oxygen reduction reaction (ORR) catalysts. In this work, atomically dispersed FeN2 on rich nitrogen doping-hollow carbon nanosphere catalysts were prepared by silica interface assists. The Fe–N/C@SiO2 catalysts with an ultrathin SiO2 layer (∼3 nm) were derived from ZIF-8@Fe/SiO2 composites. A porous SiO2 thin layer was wrapped on a ZIF-8 surface while loading Fe atoms inside silica by one-step synthesis. Different from the conventional synthetic strategy, no additional post-treatments such as etching of SiO2 coatings and second pyrolysis are required. The ORR activity and stability are highly dependent on the thickness of the SiO2 layer. The rigid SiO2 layer not only traps the volatile nitrogen species on the surface to achieve a high nitrogen doping (11.14%) but also prevents the ZIF framework from collapse, forming hierarchical porous structures. Also more importantly, single Fe atoms are anchored in situ on the outer surface of the catalysts in the form of FeN2 configuration, thus greatly boosting the ORR activities. Remarkable stability (only 1% activity attenuation after 14 h of operation) is achieved in alkaline media due to the assist of inactive silica layers

Supramolecular Anchoring of Polyoxometalate Amphiphiles into Nafion Nanophases for Enhanced Proton Conduction

Advanced proton exchange membranes (PEMs) are highly desirable in emerging sustainable energy technology. However, the further improvement of commercial perfluorosulfonic acid PEMs represented by Nafion is hindered by the lack of precise modification strategy due to their chemical inertness and low compatibility. Here, we report the robust assembly of polyethylene glycol grafted polyoxometalate amphiphile (GSiW11) into the ionic nanophases of Nafion, which largely enhances the comprehensive performance of Nafion. GSiW11 can coassemble with Nafion through multiple supramolecular interactions and realize a stable immobilization. The incorporation of GSiW11 can increase the whole proton content in the system and induce the hydrated ionic nanophase to form a wide channel for proton transport; meanwhile, GSiW11 can reinforce the Nafion ionic nanophase by noncovalent cross-linking. Based on these synergistic effects, the hybrid PEMs show multiple enhancements in proton conductivity, tensile strength, and fuel cell power density, which are all superior to the pristine Nafion. This work demonstrates the intriguing advantage of molecular nanoclusters as supramolecular enhancers to develop high-performance electrolyte materials

Mn₃O₄–CeO₂ Hollow Nanospheres for Electrochemical Determination of Hydrogen Peroxide

Introducing hollow structure by self-assembly and hard-templating methods enables the increase of specific surface areas and reaction sites toward boosting the electrochemical sensing performance of the manganese oxide-based materials. In this work, a strategy of synthesizing Mn3O4–CeO2 with nanosized hollow spheres was developed by employing cerium oxide as the support skeleton for a superior catalyzing effect toward hydrogen peroxide (H2O2) electroreduction. Herein, the effect of molar ratios of Ce and Mn on the structure and electrocatalytic property of synthesized Mn3O4–CeO2 hollow nanospheres was investigated. Profiting from abundant active sites, high porosity, large specific surface area, and the synergy of Mn3O4 and CeO2, the resulting Mn3O4–CeO2 hollow nanospheres display a wide linear range response (0.005–17 mM) with high sensitivity (176.4 μA mM–1 cm–2) for H2O2 determination. The developed sensor shows excellent stability, selectivity, and recovery for detecting H2O2 in actual samples. This work finds an efficient way to construct hollow structure through self-assembly on a hard-templating surface, providing special insight into the electrochemical properties of transition-metal oxides

Hierarchical NiMn Layered Double Hydroxide Nanostructures on Carbon Cloth for Electrochemical Detection of Hydrogen Peroxide

Transition metal layered double hydroxide (LDH) nanomaterials have gained wide attention in the fields of supercapacitors, photocatalysis, and electrocatalysis due to their large specific surface area and eminent catalytic performance. In this work, hierarchical NiMn LDH nanosheet arrays were synthesized on flexible carbon cloth (CC) through a one-step hydrothermal reaction as a self-supporting electrode. For one thing, CC can efficiently prevent the aggregation of the NiMn LDH nanosheet and accelerate the electron transfer ability as a desired electric conductor. For another, the synthesized NiMn LDH nanostructures exhibited super electrocatalytic activity toward H2O2 oxidation due to the large active surface area and the synergistic effect of Ni and Mn. Therefore, the nanostructured NiMn LDH on CC displays excellent sensing characteristic for H2O2 with a broad linear range of 1–23,000 μM, a low detection limit of 0.26 μM, and a high sensitivity of 4108 μA mM–1 cm–2. Moreover, the proposed sensor shows promising application prospects for detecting H2O2 in frozen squid and dried tofu, demonstrating its importance in the food industry and food safety

Self-Assembled Construction of Ion-Selective Nanobarriers in Electrolyte Membranes for Redox Flow Batteries

Ion-conducting membranes (ICMs) with high selectivity are important components in redox flow batteries. However it is still a challenge to break the trade-off between ion conductivity and ion selectivity, which can be resolved by the regulation of their nanostructures. Here, polyoxometalate (POM)-hybridized block copolymers (BCPs) are used as self-assembled additives to construct proton-selective nanobarriers in the ICM matrix to improve the microscopic structures and macroscopic properties of ICMs. Benefiting from the co-assembly behavior of BCPs and POMs and their cooperative noncovalent interactions with the polymer matrix, ∼50 nm ellipsoidal functional nanoassemblies with hydrophobic vanadium-shielding cores and hydrophilic proton-conducting shells are constructed in the sulfonated poly­(ether ether ketone) matrix, which leads to an overall enhancement of proton conductivity, proton selectivity, and cell performance. These results present a self-assembly route to construct functional nanostructures for the modification of polymer electrolyte membranes toward emerging energy technologies