Ligand-Aided Glycolysis of PET Using Functionalized Silica-Supported FeO Nanoparticles.

The development of efficient catalysts for the chemical recycling of poly(ethylene terephthalate) (PET) is essential to tackling the global issue of plastic waste. There has been intense interest in heterogeneous catalysts as a sustainable catalyst system for PET depolymerization, having the advantage of easy separation and reuse after the reaction. In this work, we explore heterogeneous catalyst design by comparing metal-ion (Fe) and metal-oxide nanoparticle (FeO NP) catalysts immobilized on mesoporous silica (SiO) functionalized with different N-containing amine ligands.

PdAu Nanosheets for Visible-Light-Driven Suzuki Cross-Coupling Reactions.

Combining a two-dimensional (2D) morphology and plasmonic photocatalysis represents an efficient design for light-driven organic transformations. We report a one-pot synthesis of surfactant templated PdAu nanosheets (NSs). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses show the formation of 2D PdAu structures was initiated through nanoparticle seeds dispersed in the alkyl ammonium salt surfactant which acted as a template for the growth into NSs.

Controlled morphology and dimensionality evolution of NiPd bimetallic nanostructures.

Controlling the morphology of noble metal-based nanostructures is a powerful strategy for optimizing their catalytic performance. Here, we report a one-pot aqueous synthesis of versatile NiPd nanostructures at room temperature without employing organic solvents or surfactants. The synthesis can be tuned to form zero-dimensional (0D) architectures, such as core-shell and hollow nanoparticles (NPs), as well as nanostructures with higher dimensionality, such as extended nanowire networks and three-dimensional (3D) nanodendrites.

Stabilization of Black Phosphorus by Sonication-Assisted Simultaneous Exfoliation and Functionalization.

Black phosphorus (BP) has extraordinary properties, but its ambient instability remains a critical challenge. Functionalization has been employed to overcome the sensitivity of BP to ambient conditions while preserving its properties. Herein, a simultaneous exfoliation-functionalization process is reported that functionalizes BP flakes during exfoliation and thus provides increased protection, which can be attributed to minimal exposure of the flakes to ambient oxygen and water.

Evaluating the Surface Chemistry of Black Phosphorus during Ambient Degradation.

Black phosphorus (BP) is emerging as a promising candidate for electronic, optical, and energy storage applications. However, its poor ambient stability remains a critical challenge. Evaluation of few-layer liquid-exfoliated BP during ambient exposure using X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy allows its surface chemistry to be investigated.

Functionalization of SiO Surfaces for Si Monolayer Doping with Minimal Carbon Contamination.

Monolayer doping (MLD) involves the functionalization of semiconductor surfaces followed by an annealing step to diffuse the dopant into the substrate. We report an alternative doping method, oxide-MLD, where ultrathin SiO overlayers are functionalized with phosphonic acids for doping Si. Similar peak carrier concentrations were achieved when compared with hydrosilylated surfaces (∼2 × 10 atoms/cm).

Fingerprints of a size-dependent crossover in the dimensionality of electronic conduction in Au-seeded Ge nanowires.

We studied the electrical transport properties of Au-seeded germanium nanowires with radii ranging from 11 to 80 nm at ambient conditions. We found a non-trivial dependence of the electrical conductivity, mobility and carrier density on the radius size. In particular, two regimes were identified for large (lightly doped) and small (stronger doped) nanowires in which the charge-carrier drift is dominated by electron-phonon and ionized-impurity scattering, respectively.

Influence of Binders and Solvents on Stability of Ru/RuO Nanoparticles on ITO Nanocrystals as Li-O Battery Cathodes.

Fundamental research on Li-O batteries remains critical, and the nature of the reactions and stability are paramount for realising the promise of the Li-O system. We report that indium tin oxide (ITO) nanocrystals with supported 1-2 nm oxygen evolution reaction (OER) catalyst Ru/RuO nanoparticles (NPs) demonstrate efficient OER processes, reduce the recharge overpotential of the cell significantly and maintain catalytic activity to promote a consistent cycling discharge potential in Li-O cells even when the ITO support nanocrystals deteriorate from the very first cycle. The Ru/RuO nanoparticles lower the charge overpotential compared with those for ITO and carbon-only cathodes and have the greatest effect in DMSO electrolytes with a solution-processable F-free carboxymethyl cellulose (CMC) binder (<3.

2D and 3D photonic crystal materials for photocatalysis and electrochemical energy storage and conversion.

This perspective reviews recent advances in inverse opal structures, how they have been developed, studied and applied as catalysts, catalyst support materials, as electrode materials for batteries, water splitting applications, solar-to-fuel conversion and electrochromics, and finally as photonic photocatalysts and photoelectrocatalysts. Throughout, we detail some of the salient optical characteristics that underpin recent results and form the basis for light-matter interactions that span electrochemical energy conversion systems as well as photocatalytic systems. Strategies for using 2D as well as 3D structures, ordered macroporous materials such as inverse opals are summarized and recent work on plasmonic-photonic coupling in metal nanoparticle-infiltrated wide band gap inverse opals for enhanced photoelectrochemistry are provided.

Engineering Metallic Nanoparticles for Enhancing and Probing Catalytic Reactions.

Recent developments in tailoring the structural and chemical properties of colloidal metal nanoparticles (NPs) have led to significant enhancements in catalyst performance. Controllable colloidal synthesis has also allowed tailor-made NPs to serve as mechanistic probes for catalytic processes. The innovative use of colloidal NPs to gain fundamental insights into catalytic function will be highlighted across a variety of catalytic and electrocatalytic applications.

Monolayer Doping of Si with Improved Oxidation Resistance.

In this article, the functionalization of planar silicon with arsenic- and phosphorus-based azides was investigated. Covalently bonded and well-ordered alkyne-terminated monolayers were prepared from a range of commercially available dialkyne precursors using a well-known thermal hydrosilylation mechanism to form an acetylene-terminated monolayer. The terminal acetylene moieties were further functionalized through the application of copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions between dopant-containing azides and the terminal acetylene groups.

Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping.

Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.

Germanium oxide removal by citric acid and thiol passivation from citric acid-terminated Ge(100).

Many applications of germanium (Ge) are underpinned by effective oxide removal and surface passivation. This important surface treatment step often requires H-X (X = Cl, Br, I) or HF etchants. Here, we show that aqueous citric acid solutions are effective in the removal of GeOx.

The origin of shape sensitivity in palladium-catalyzed Suzuki-Miyaura cross coupling reactions.

The shape sensitivity of Pd catalysts in Suzuki-Miyaura coupling reactions is studied using nanocrystals enclosed by well-defined surface facets. The catalytic performance of Pd nanocrystals with cubic, cuboctahedral and octahedral morphologies are compared. Superior catalytic reactivity is observed for Pd NCs with {100} surface facets compared to {111} facets.

Palladium-catalyzed coupling reactions for the functionalization of Si surfaces: superior stability of alkenyl monolayers.

Palladium-catalyzed Suzuki, Heck, and Sonogashira coupling reactions were studied as reaction protocols for organic modification of Si surfaces. These synthetically useful protocols allow for surface modification of alkene, alkyne, and halide terminated surfaces. Surface oxidation and metal contamination were assessed by X-ray photoelectron spectroscopy.

Probing the origin of in situ generated nanoparticles as sustainable oxidation catalysts.

A novel method for the in situ generation of catalytically active small metal nanoparticles, by anion extrusion on a parent porous copper chloropyrophosphate framework, has been developed to generate gold, platinum and palladium nanoparticles for sustainable catalytic oxidations using molecular oxygen as the oxidant. Transmission electron microscopy coupled with detailed structural and physico-chemical characterisation, in combination with in-depth kinetic analysis have afforded profound insights into the nature of the active site for facilitating structure-property correlations.

Investigation into the voltammetric behaviour and detection of selenium(IV) at metal electrodes in diverse electrolyte media.

The voltammetric behaviour of selenium(IV) was studied at platinum and gold electrodes in sulphuric acid, perchloric acid and potassium chloride media as a basis for its voltammetric detection. The best voltammetric behaviour was recorded at gold electrodes with perchloric acid as the supporting electrolyte. The concomitant presence of metals, such as copper or lead, and of model biomolecules, such as bovine serum albumin, in the solution resulted in a deterioration of the electrochemical response for selenium(IV).