Self‐Supported PtAuP Alloy Nanotube Arrays with Enhanced Activity and Stability for Methanol Electro‐Oxidation

Inhibiting CO formation can more directly address the problem of CO poisoning during methanol electro‐oxidation. In this study, 1D self‐supported porous PtAuP alloy nanotube arrays (ANTAs) are synthesized via a facile electro‐codeposition approach and present enhanced activity and improved resistance to CO poisoning through inhibiting CO formation (non‐CO pathway) during the methanol oxidation reaction in acidic medium. This well‐controlled Pt‐/transition metal‐/nonmetal ternary nanostructure exhibits a specific electroactivity twice as great as that of PtAu alloy nanotube arrays and Pt/C. At the same time, PtAuP ANTAs show a higher ratio of forward peak current density (I_f) to backward peak current density (I_b) (2.34) than PtAu ANTAs (1.27) and Pt/C (0.78). The prominent I_f/I_b value of PtAuP ANTAs indicates that most of the intermediate species are electro‐oxidized to carbon dioxide in the forward scan, which highlights the high electroactivity for methanol electro‐oxidation.     

Crystal Facet Induced Single‐Atom Pd/CoxOy on a Tunable Metal–Support Interface for Low Temperature Catalytic Oxidation

Atomic dispersed metal sites in single‐atom catalysts are highly mobile and easily sintered to form large particles, which deteriorates the catalytic performance severely. Moreover, lack of criterion concerning the role of the metal–support interface prevents more efficient and wide application. Here, a general strategy is reported to synthesize stable single atom catalysts by crafting on a variety of cobalt‐based nanoarrays with precisely controlled architectures and compositions. The highly uniform, well‐aligned, and densely packed nanoarrays provide abundant oxygen vacancies (17.48%) for trapping Pd single atoms and lead to the creation of 3D configured catalysts, which exhibit very competitive activity toward low temperature CO oxidation (100% conversion at 90 °C) and prominent long‐term stability (continuous conversion at 60 °C for 118 h). Theoretical calculations show that O vacancies at high‐index {112} facet of Co_xO_y nanocrystallite are preferential sites for trapping single atoms, which guarantee strong interface adhesion of Pd species to cobalt‐based support and play a pivotal role in preventing the decrement of activity, even under moisture‐rich conditions (≈2% water vapor). The progress presents a promising opportunity for tailoring catalytic properties consistent with the specific demand on target process, beyond a facile design with a tunable metal–support interface.     

Modulation of Molecular Spatial Distribution and Chemisorption with Perforated Nanosheets for Ethanol Electro‐oxidation

Integrating thermodynamically favorable ethanol reforming reactions with hybrid water electrolysis will allow room‐temperature production of high‐value organic products and decoupled hydrogen evolution. However, electrochemical reforming of ethanol has not received adequate attention due to its low catalytic efficiency and poor selectivity, which are caused by the multiple groups and chemical bonds of ethanol. In addition to the thermodynamic properties affected by the electronic structure of the catalyst, the dynamics of molecule/ion dynamics in electrolytes also play a significant role in the efficiency of a catalyst. The relatively large size and viscosity of the ethanol molecule necessitates large channels for molecule/ion transport through catalysts. Perforated CoNi hydroxide nanosheets are proposed as a model catalyst to synergistically regulate the dynamics of molecules and electronic structures. Molecular dynamics simulations directly reveal that these nanosheets can act as a “dam” to enrich ethanol molecules and facilitate permeation through the nanopores. Additionally, the charge transfer behavior of heteroatoms modifies the local charge density to promote molecular chemisorption. As expected, the perforated nanosheets exhibit a small potential (1.39 V) and high Faradaic efficiency for the conversion of ethanol into acetic acid. Moreover, the concept in this work provides new perspectives for exploring other molecular catalysts.     

Ordered Arrangement and Optical Properties of Silica‐Stabilized Gold Nanoparticle–PNIPAM Core–Satellite Clusters for Sensitive Raman Detection

Gold–polymer hybrid nanoparticles attract wide interest as building blocks for the engineering of photonic materials and plasmonic (active) metamaterials with unique optical properties. In particular, the coupling of the localized surface plasmon resonances of individual metal nanostructures in the presence of nanometric gaps can generate highly enhanced and confined electromagnetic fields, which are frequently exploited for metal‐enhanced light–matter interactions. The optical properties of plasmonic structures can be tuned over a wide range of properties by means of their geometry and the size of the inserted nanoparticles as well as by the degree of order upon assembly into 1D, 2D, or 3D structures. Here, the synthesis of silica‐stabilized gold–poly(N‐isopropylacrylamide) (SiO₂‐Au‐PNIPAM) core–satellite superclusters with a narrow size distribution and their incorporation into ordered self‐organized 3D assemblies are reported. Significant alterations of the plasmon resonance are found for different assembled structures as well as strongly enhanced Raman signatures are observed. In a series of experiments, the origin of the highly enhanced signals can be assigned to the interlock areas of adjacent SiO₂‐Au‐PNIPAM core–satellite clusters and their application for highly sensitive nanoparticle‐enhanced Raman spectroscopy is demonstrated.     

Ultrafine Co3O4 Nanoparticles within Nitrogen‐Doped Carbon Matrix Derived from Metal–Organic Complex for Boosting Lithium Storage and Oxygen Evolution Reaction

Transition metal oxides have recently received great attention for application in advanced lithium‐ion batteries (LIBs) and oxygen evolution reaction (OER). Herein, the ethylenediaminetetraacetic cobalt complex as a precursor to synthesize ultrafine Co₃O₄ nanoparticles encapsulated into a nitrogen‐doped carbon matrix (NC) composites is presented. The as‐prepared Co₃O₄/NC‐350 obtained by pyrolysis at 350 °C demonstrates superior rate performance (372 mAh g^?1 at 5.0 A g^?1) and high cycling stability (92% capacity retention after 300 cycles at 1.0 A g^?1) as anode for LIBs. When evaluated as an electrocatalyst for OER, the Co₃O₄/NC‐350 achieves an overpotential of 298 mV at a current density of 10 mA cm^?2. The NC‐encapsualted porous hierarchical structure assures fast and continuous electron transportation, high activity sites, and strong structural integrity. This works offers novel complex precursors for synthesizing transition metal–based electrodes for boosting electrochemical energy conversion and storage.     

Fluorescent–Magnetic Hybrid Nanoparticles Induce a Dose‐Dependent Increase in Proinflammatory Response in Lung Cells in vitro Correlated with Intracellular Localization

Iron–platinum nanoparticles embedded in a poly(methacrylic acid) (PMA) polymer shell and fluorescently labeled with the dye ATTO 590 (FePt–PMA–ATTO‐2%) are investigated in terms of their intracellular localization in lung cells and potential to induce a proinflammatory response dependent on concentration and incubation time. A gold core coated with the same polymer shell (Au–PMA–ATTO‐2%) is also included. Using laser scanning and electron microscopy techniques, it is shown that the FePt–PMA–ATTO‐2% particles penetrate all three types of cell investigated but to a higher extent in macrophages and dendritic cells than epithelial cells. In both cell types of the defense system but not in epithelial cells, a particle‐dose‐dependent increase of the cytokine tumor necrosis factor alpha (TNFα) is found. By comparing the different nanoparticles and the mere polymer shell, it is shown that the cores combined with the shells are responsible for the induction of proinflammatory effects and not the shells alone. It is concluded that the uptake behavior and the proinflammatory response upon particle exposure are dependent on the time, cell type, and cell culture.     

Facile Synthesis of Ultrasmall CoS2 Nanoparticles within Thin N‐Doped Porous Carbon Shell for High Performance Lithium‐Ion Batteries

Cobalt sulfide (CoS₂) is considered one of the most promising alternative anode materials for high‐performance lithium‐ion batteries (LIBs) by virtue of its remarkable electrical conductivity, high theoretical capacity, and low cost. However, it suffers from a poor cycling stability and low rate capability because of its volume expansion and dissolution of the polysulfide intermediates in the organic electrolytes during the battery charge/discharge process. In this study, a novel porous carbon/CoS₂ composite is prepared by using nano metal–organic framework (MOF) templates for high‐preformance LIBs. The as‐made ultrasmall CoS₂ (15 nm) nanoparticles in N‐rich carbon exhibit promising lithium storage properties with negligible loss of capacity at high charge/discharge rate. At a current density of 100 mA g^?1, a capacity of 560 mA h g^?1 is maintained after 50 cycles. Even at a current density as high as 2500 mA g^?1, a reversible capacity of 410 mA h g^?1 is obtained. The excellent and highly stable battery performance should be attributed to the synergism of the ultrasmall CoS₂ particles and the thin N‐rich porous carbon shells derieved from nanosized MOF precusors.     

Space‐Confined Synthesis of ZIF‐67 Nanoparticles in Hollow Carbon Nanospheres for CO2 Adsorption

Herein, the design and synthesis of ZIF‐67 nanoparticles (NPs) with tunable size grown inside hollow carbon nanospheres (ZIF‐67@HCSs) via a space‐confined strategy is reported. HCSs are first prepared via pyrolysis of polystyrene@polypyrrole (PS@PPy) composite nanospheres. Further infiltration of 2‐methylimidazole (MI) into the HCSs (MI@HCSs) using a melting‐diffusion strategy, followed by immersing MI@HCSs into Co(NO₃)₂ solution through the pores and channels of HCSs results in the formation of ZIF‐67@HCSs. The as‐synthesized ZIF‐67@HCSs with tunable ZIF‐67 size is achieved by changing the amount of MI. Due to the high pore volume provided by nanoscale ZIF‐67 NPs, the as‐prepared core–shell ZIF‐67@HCSs exhibit outstanding adsorption capacity for CO₂.     

Co9S8 Nanoparticles‐Embedded N/S‐Codoped Carbon Nanofibers Derived from Metal–Organic Framework‐Wrapped CdS Nanowires for Efficient Oxygen Evolution Reaction

Metal–organic frameworks (MOFs) with tunable compositions and morphologies are recognized as efficient self‐sacrificial templates to achieve function‐oriented nanostructured materials. Moreover, it is urgently needed to develop highly efficient noble metal‐free oxygen evolution reaction (OER) electrocatalysts to accelerate the development of overall water splitting green energy conversion systems. Herein, a facile and cost‐efficient strategy to synthesize Co₉S₈ nanoparticles‐embedded N/S‐codoped carbon nanofibers (Co₉S₈/NSCNFs) as highly active OER catalyst is developed. The hybrid precursor of core–shell ZIF‐wrapped CdS nanowires is first prepared and then leads to the formation of uniformly dispersed Co₉S₈/N, S‐codoped carbon nanocomposites through a one‐step calcination reaction. The optimal Co₉S₈/NSCNFs‐850 is demonstrated to possess excellent electrocatalytic performance for OER in 1.0 m KOH solution, affording a low overpotential of 302 mV to reach the current density of 10 mA cm^?2, a small Tafel slope of 54 mV dec^?1, and superior long‐term stability for 1000 cyclic voltammetry cycles. The favorable results raise a concept of exploring more MOF‐based nanohybrids as precursors to induce the synthesis of novel porous nanomaterials as non‐noble‐metal electrocatalysts for sustainable energy conversion.     

Facile Synthesis of Yolk–Shell‐Structured Triple‐Hybridized Periodic Mesoporous Organosilica Nanoparticles for Biomedicine

The synthesis of mesoporous nanoparticles with controllable structure and organic groups is important for their applications. In this work, yolk–shell‐structured periodic mesoporous organosilica (PMO) nanoparticles simultaneously incorporated with ethane‐, thioether‐, and benzene‐bridged moieties are successfully synthesized. The preparation of the triple‐hybridized PMOs is via a cetyltrimethylammonium bromide‐directed sol–gel process using mixed bridged silsesquioxanes as precursors and a following hydrothermal treatment. The yolk–shell‐structured triple‐hybridized PMO nanoparticles have large surface area (320 m² g^–1), ordered mesochannels (2.5 nm), large pore volume (0.59 cm³ g^–1), uniform and controllable diameter (88–380 nm), core size (22–110 nm), and shell thickness (13–45 nm). In vitro cytotoxicity, hemolysis assay, and histological studies demonstrate that the yolk–shell‐structured triple‐hybridized PMO nanoparticles have excellent biocompatibility. Moreover, the organic groups in the triple‐hybridized PMOs endow them with an ability for covalent connection of near‐infrared fluorescence dyes, a high hydrophobic drug loading capacity, and a glutathione‐responsive drug release property, which make them promising candidates for applications in bioimaging and drug delivery.     

MOF‐Based Metal‐Doping‐Induced Synthesis of Hierarchical Porous CuN/C Oxygen Reduction Electrocatalysts for Zn–Air Batteries

A transition‐metal–nitrogen/carbon (TM–N/C, TM = Fe, Co, Ni, etc.) system is a popular, nonprecious‐metal oxygen reduction reaction (ORR) electrocatalyst for fuel cell and metal–air battery applications. However, there remains a lack of comprehensive understanding about the ORR electrocatalytic mechanism on these catalysts, especially the roles of different forms of metal species on electrocatalytic performance. Here, a novel Cu?N/C ORR electrocatalyst with a hybrid Cu coordination site is successfully fabricated with a simple but efficient metal–organic‐framework‐based, metal‐doping‐induced synthesis strategy. By directly pyrolyzing Cu‐doped zeolitic‐imidazolate‐framework‐8 polyhedrons, the obtained Cu?N/C catalyst can achieve a high specific surface area of 1182 m² g^?1 with a refined hierarchical porous structure and a high surface N content of 11.05 at%. Moreover, regulating the Cu loading can efficiently tune the states of Cu(II) and Cu⁰, resulting in the successful construction of a highly active hybrid coordination site of N?Cu(II)?Cu⁰ in derived Cu?N/C catalysts. As a result, the optimized 25% Cu?N/C catalyst possesses a high ORR activity and stability in 0.1 m KOH solution, as well as excellent performance and stability in a Zn–air battery.     

α‐Ni(OH)2 Originated from Electro‐Oxidation of NiSe2 Supported by Carbon Nanoarray on Carbon Cloth for Efficient Water Oxidation

Development of effective oxygen evolution reaction (OER) electrocatalysts has been intensively studied to improve water splitting efficiency and cost effectiveness in the last ten years. However, it is a big challenge to obtain highly efficient and durable OER electrocatalysts with overpotentials below 200 mV at 10 mA cm^?2 despite the efforts made to date. In this work, the successful synthesis of supersmall α‐Ni(OH)₂ is reported through electro‐oxidation of NiSe₂ loaded onto carbon nanoarrays. The obtained α‐Ni(OH)₂ shows excellent activity and long‐term stability for OER, with an overpotential of only 190 mV at the current density of 10 mA cm^?2, which represents a highly efficient OER electrocatalyst. The excellent activity could be ascribed to the large electrochemical surface area provided by the carbon nanoarray, as well as the supersmall size (≈10 nm) of α‐Ni(OH)₂ which possess a large number of active sites for the reaction. In addition, the phase evolution of α‐Ni(OH)₂ from NiSe₂ during the electro‐oxidation process was monitored with in situ X‐ray absorption fine structure (XAFS) analysis.     

Ambient Fast Synthesis and Active Sites Deciphering of Hierarchical Foam‐Like Trimetal–Organic Framework Nanostructures as a Platform for Highly Efficient Oxygen Evolution Electrocatalysis

Metal–organic frameworks (MOFs) have attracted tremendous interest due to their promising applications including electrocatalysis originating from their unique structural features. However, it remains a challenge to directly use MOFs for oxygen electrocatalysis because it is quite difficult to manipulate their dimension, composition, and morphology of the MOFs with abundant active sites. Here, a facile ambient temperature synthesis of unique NiCoFe‐based trimetallic MOF nanostructures with foam‐like architecture is reported, which exhibit extraordinary oxygen evolution reaction (OER) activity as directly used catalyst in alkaline condition. Specifically, the (Ni₂Co₁)_0.925Fe_0.075‐MOF‐NF delivers a minimum overpotential of 257 mV to reach the current density of 10 mA cm^?2 with a small Tafel slope of 41.3 mV dec^?1 and exhibits high durability after long‐term testing. More importantly, the deciphering of the possible origination of the high activity is performed through the characterization of the intermediates during the OER process, where the electrochemically transformed metal hydroxides and oxyhydroxides are confirmed as the active species.     

ZnS/C/MoS2 Nanocomposite Derived from Metal–Organic Framework for High‐Performance Photo‐Electrochemical Immunosensing of Carcinoembryonic Antigen

A hexafluorophosphate ionic liquid is used as a functional monomer to prepare a metal–organic framework (Zn‐MOF). Zn‐MOF is used as a template for MoS₂ nanosheets synthesis and further carbonized to yield light‐responsive ZnS/C/MoS₂ nanocomposites. Zn‐MOF, carbonized‐Zn‐MOF, and ZnS/C/MoS₂ nanocomposites are characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, X‐ray diffraction pattern, scanning electron microscopy (SEM), element mapping, Raman spectroscopy, X‐ray photoelectron spectroscopy, fluorescence, and nitrogen‐adsorption analysis. Carcinoembryonic antigen (CEA) is selected as a model to construct an immunosensing platform to evaluate the photo‐electrochemical (PEC) performances of ZnS/C/MoS₂ nanocomposites. A sandwich‐type PEC immunosensor is fabricated by immobilizing CEA antibody (Ab₁) onto the ZnS/C/MoS₂/GCE surface, subsequently binding CEA and the alkaline phosphatase‐gold nanoparticle labeled CEA antibody (ALP‐Au‐Ab₂). The catalytic conversion of vitamin C magnesium phosphate produces ascorbic acid (AA). Upon being illuminated, AA can react with photogenerated holes from ZnS/C/MoS₂ nanocomposites to generate a photocurrent for quantitative assay. Under optimized experimental conditions, the PEC immunosensor exhibits excellent analytical characteristics with a linear range from 2.0 pg mL^?1 to 10.0 ng mL^?1 and a detection limit of 1.30 pg mL^?1 (S/N = 3). The outstanding practicability of this PEC immunosensor is demonstrated by accurate assaying of CEA in clinical serum samples.     

Large‐Pore Mesoporous CeO2–ZrO2 Solid Solutions with In‐Pore Confined Pt Nanoparticles for Enhanced CO Oxidation

Active and stable catalysts are highly desired for converting harmful substances (e.g., CO, NO_x) in exhaust gases of vehicles into safe gases at low exhaust temperatures. Here, a solvent evaporation–induced co‐assembly process is employed to design ordered mesoporous Ce_xZr_1?xO₂ (0 ≤ x ≤ 1) solid solutions by using high‐molecular‐weight poly(ethylene oxide)‐block‐polystyrene as the template. The obtained mesoporous Ce_xZr_1?xO₂ possesses high surface area (60–100 m² g^?1) and large pore size (12–15 nm), enabling its great capacity in stably immobilizing Pt nanoparticles (4.0 nm) without blocking pore channels. The obtained mesoporous Pt/Ce_0.8Zr_0.2O₂ catalyst exhibits superior CO oxidation activity with a very low T₁₀₀ value of 130 °C (temperature of 100% CO conversion) and excellent stability due to the rich lattice oxygen vacancies in the Ce_0.8Zr_0.2O₂ framework. The simulated catalytic evaluations of CO oxidation combined with various characterizations reveal that the intrinsic high surface oxygen mobility and well‐interconnected pore structure of the mesoporous Pt/Ce_0.8Zr_0.2O₂ catalyst are responsible for the remarkable catalytic efficiency. Additionally, compared with mesoporous Pt/Ce_xZr_1?xO₂‐s with small pore size (3.8 nm), ordered mesoporous Pt/Ce_xZr_1?xO₂ not only facilitates the mass diffusion of reactants and products, but also provides abundant anchoring sites for Pt nanoparticles and numerous exposed catalytically active interfaces for efficient heterogeneous catalysis.     

One‐Step In Situ Growth of Iron–Nickel Sulfide Nanosheets on FeNi Alloy Foils: High‐Performance and Self‐Supported Electrodes for Water Oxidation

Efficient and durable oxygen evolution reaction (OER) catalysts are highly required for the cost‐effective generation of clean energy from water splitting. For the first time, an integrated OER electrode based on one‐step direct growth of metallic iron–nickel sulfide nanosheets on FeNi alloy foils (denoted as Fe? Ni₃S₂/FeNi) is reported, and the origin of the enhanced OER activity is uncovered in combination with theoretical and experimental studies. The obtained Fe? Ni₃S₂/FeNi electrode exhibits highly catalytic activity and long‐term stability toward OER in strong alkaline solution, with a low overpotential of 282 mV at 10 mA cm^?2 and a small Tafel slope of 54 mV dec^?1. The excellent activity and satisfactory stability suggest that the as‐made electrode provides an attractive alternative to noble metal‐based catalysts. Combined with density functional theory calculations, exceptional OER performance of Fe? Ni₃S₂/FeNi results from a combination of efficient electron transfer properties, more active sites, the suitable O₂ evolution kinetics and energetics benefited from Fe doping. This work not only simply constructs an excellent electrode for water oxidation, but also provides a deep understanding of the underlying nature of the enhanced OER performance, which may serve as a guide to develop highly effective and integrated OER electrodes for water splitting.