Surfaces decorated with uniformly dispersed catalytically active nanoparticles play a key role in many fields, including renewable energy and catalysis. Typically, these structures are prepared by ...deposition techniques, but alternatively they could be made by growing the nanoparticles in situ directly from the (porous) backbone support. Here we demonstrate that growing nano-size phases from perovskites can be controlled through judicious choice of composition, particularly by tuning deviations from the ideal ABO3 stoichiometry. This non-stoichiometry facilitates a change in equilibrium position to make particle exsolution much more dynamic, enabling the preparation of compositionally diverse nanoparticles (that is, metallic, oxides or mixtures) and seems to afford unprecedented control over particle size, distribution and surface anchorage. The phenomenon is also shown to be influenced strongly by surface reorganization characteristics. The concept exemplified here may serve in the design and development of more sophisticated oxide materials with advanced functionality across a range of possible domains of application.
Metal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to ...their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, allowing one to subject them to further chemical transformations to alter their composition, structure and functionality dramatically, while preserving their initial spatial arrangement. We refer to this concept as chemistry at a point and illustrate it by tracking individual nanoparticles throughout various chemical transformations. We demonstrate its remarkable practical utility by preparing a nanostructured earth abundant metal catalyst which rivals platinum on a weight basis over hundreds of hours of operation. Our concept enables the design of compositionally diverse confined oxide particles with superior stability and catalytic reactivity.
Particle size does not affect the intrinsic activity of silica-supported nickel nanoparticles in dry reforming at 500°C. Display omitted
► Different silica supported nickel catalyst prepared with ...varying particle size (1.6–7.3nm). ► Neutral silica support favours a very high reduction degree (> 90%) at 500°C. ► Intrinsic Ni/SiO2 performances are independent of nickel particle size in dry reforming at 773K. ► The H2/CO ratio is controlled by the thermodynamic of the fast reverse water gas shift reaction.
The influence of nickel particle size in the range of 1.6–7.3nm on catalyst performance in low temperature CO2 reforming of methane reaction has been investigated using well-defined catalysts based on a neutral silica support. XAS and XPS studies indicated a reduction degree greater than 90%. The intrinsic Ni/SiO2 performances were found to be independent of nickel particle size in dry reforming at 773K using a CH4/CO2 ratio of 1.3 at 1atm, both at an early stage and in steady state conditions. The H2/CO ratio was also found to be structure in sensitive but is controlled by thermodynamics through the faster reverse water gas shift reaction.
Metal particles supported on oxide surfaces are used as catalysts for a wide variety of processes in the chemical and energy conversion industries. For catalytic applications, metal particles are ...generally formed on an oxide support by physical or chemical deposition, or less commonly by exsolution from it. Although fundamentally different, both methods might be assumed to produce morphologically and functionally similar particles. Here we show that unlike nickel particles deposited on perovskite oxides, exsolved analogues are socketed into the parent perovskite, leading to enhanced stability and a significant decrease in the propensity for hydrocarbon coking, indicative of a stronger metal-oxide interface. In addition, we reveal key surface effects and defect interactions critical for future design of exsolution-based perovskite materials for catalytic and other functionalities. This study provides a new dimension for tailoring particle-substrate interactions in the context of increasing interest for emergent interfacial phenomena.
•The Prometheus Bio fentanyl immunoassay test strips detected 45 ng/mL of fentanyl.•The fentanyl immunoassay strips cross-reacted with 16 of 18 tested fentanyl analogs.•No false positives were found ...for non-fentanyl drugs or cutting agents.•The fentanyl strips remained effective when fentanyl was present in a mixture.•A cotton swab in water is effective for sampling alternative matrices for fentanyl.
Ion mobility spectrometry is used for the rapid detection of drugs at points of security but are unable to differentiate some drugs leading to the instrument alarming for a drug not present in the sample. This can be particularly problematic for samples that alarm for fentanyl. In this study, fentanyl immunoassay strips were evaluated for use as a secondary test for fentanyl, including for the testing of alternative matrices, such as powders, e-liquids, and infused papers and textiles.
The limit of detection of fentanyl immunoassay strips was examined along with their selectivity to 18 fentanyl analogsand 72 other drugs and cutting agents. The effectiveness of the test strips at the detection of fentanyl in the presence of other drugs was examined by testing a series of concentrations of fentanyl in solution in combination with other drugs. The testing of alternative matrices was explored with laboratory prepared samples through sampling with cotton buds and extraction in water.
The fentanyl immunoassay strips detected fentanyl at concentrations of 45 ng/mL and reacted with 16 of 18 tested fentanyl analogs with carfentanil and norfentanyl being the only analogs to not react. There was no reactivity with other drugs or cutting agents. The effectiveness of the fentanyl test strips was not reduced when fentanyl was mixed with other drugs. Fentanyl was successfully detected with high sensitivity in all alternative matrices.
The fentanyl immunoassay strips were found to be an effective secondary test for fentanyl and at least 16 fentanyl analogs in seized drug samples, including when mixed with other drugs. The effectiveness of the sampling methods for alternative matrices should be further evaluated using fentanyl and fentanyl analog casework samples. The use of this method by law enforcement and other agencies should be examined to assess its effectiveness and ease of use in operational settings.
An aqueous solution method is developed for the facile synthesis of Cl‐containing SnSe nanoparticles in 10 g quantities per batch. The particle size and Cl concentration of the nanoparticles can be ...efficiently tuned as a function of reaction duration. Hot pressing produces n‐type Cl‐doped SnSe nanostructured compacts with thermoelectric power factors optimized via control of Cl dopant concentration. This approach, combining an energy‐efficient solution synthesis with hot pressing, provides a simple, rapid, and low‐cost route to high performance n‐type SnSe thermoelectric materials.
An aqueous solution method is developed for the scalable synthesis of Cl‐containing SnSe nanoparticles with tuneable particle size and Cl concentration. Hot pressing produces n‐type Cl‐doped SnSe nanostructured compacts with thermoelectric power factors optimized via control of Cl dopant concentration.
Data underpinning science have become one of the most precious assets in research, and while the principles of FAIR (Findable, Accessible, Interoperable and Reusable) have been put forward as a guide ...to how to approach data handling, data sharing and long-term storage still remain a challenge for many research areas including forensic science. The reporting and the sharing of data can be made easier by giving them structure, the use of suitable labels and the inclusion of descriptors collated into metadata prior to their deposition in repositories with persistent identifiers. Such a systematic approach would strengthen the quality and the integrity of research while providing greater transparency to published materials.
In forensic science, a robust and sound interpretation and evaluation of transferred fibre evidence requires an understanding of the principles and mechanisms that underpin fibre transfer, yet ...existing research lacks consistency and repeatability. This study investigates the impact of washing activities on both the release of fibres into wastewater and the transfer of constituent fibres from donor garments to receiver swatches. Using a low-cost friction tester and automated data collection through photography and ImageJ image processing software, controlled conditions were maintained for repeated experiments. Results indicated significant fibre release during wash cycles, with load size and donor garment history playing crucial roles. The donor garments subjected to repetitive washes exhibit a progressive decrease in the number of fibres transferred, independently of the load size. This study underscores the importance of considering a garment's washing history in forensic science contexts, but also for consistency in the way that data are collected.
ZnO spherical particles exposing only the (0001) planes are prepared by an established solvothermal method using a water–ethylene glycol (EG) mix as a solvent. It is found that poorly crystalline ...nanoparticles form first, followed by their aggregation into microspheres consisting of crystallites embedded in EG and precursor molecules/ions. The grown up nanocrystallites and nanocones in the microspheres are all radially aligned. The possible formation mechanisms, in particular, the roles of water molecules, EG, and the intrinsic dipolar field of ZnO crystals, are discussed. X‐ray photoelecton spectroscopy experiments indicate that the spherical particles are terminated solely by zinc atoms. Brunauer–Emmett–Teller measurements in conjunction with the degradation of methylene blue dye data demonstrate that the photocatalytic performance of the ZnO spheres depends on the growth time and is significantly improved compared to traditional ZnO nanorods. This study is a rare example which combines nanostructural characterization of ZnO particles terminated with a single (0001) plane of known Zn2+‐polarity with their photocatalytic performance.
ZnO spherical particles exposing only Zn2+–(0001) polar planes are prepared via a solvothermal route using a water–ethylene glycol solvent mix. The roles of water molecules, ethylene glycol, and the intrinsic dipolar field of ZnO crystals are discussed. BET measurements in conjunction with the degradation of methylene blue dye data demonstrate their enhanced photocatalytic performance.
A scheme for the generation of bimetallic nanoparticles is presented which combines electrodeposition of one type of metal, coordinated to a self-assembled monolayer (SAM), with another metal ...deposited from the bulk electrolyte. In this way PdCu nanoparticles are generated by initial complexation of Pd
2+
to a SAM of 3-(4-(pyridine-4-yl)phenyl)propane-1-thiol (PyP3) on Au/mica and subsequent reduction in an acidic aqueous CuSO
4
electrolyte. Cyclic voltammetry reveals that the onset of Cu deposition is triggered by Pd reduction. Scanning tunneling microscopy (STM) shows that layers of connected particles are formed with an average thickness of less than 3 nm and lateral dimensions of particles in the range of 2 to 5 nm. In X-ray photoelectron spectra a range of binding energies for the Pd 3d signal is observed whereas the Cu 2p signal appears at a single binding energy, even though chemically different Cu species are present: normal and more noble Cu. Up to three components are seen in the N 1s signal, one originating from protonated pyridine moieties, the others reflecting the SAM-metal interaction. It is suggested that the coordination controlled electrodeposition yields layers of particles composed of a Pd core and a Cu shell with a transition region of a PdCu alloy. Deposited on top of the PyP3 SAM, the PdCu particles exhibit weak adhesion which is exploited for patterning by selective removal of particles employing scanning probe techniques. The potential for patterning down to the sub-10 nm scale is demonstrated. Harnessing the deposition contrast between native and PdCu loaded PyP3 SAMs, structures thus created can be developed into patterned continuous layers.
Electrochemical reduction of Pd-ions coordinated to a thiol self-assembled monolayer controls Cu deposition from the bulk electrolyte.
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