A strategy to modulate the electrocatalytic activity of copper towards CO 2 reduction involving adsorption of acrylamide, acrylic acid and allylamine polymers is presented. Modification of electrodeposited copper foam with poly(acrylamide) leads to a significant enhancement in faradaic efficiency for ethylene from 13% (unmodified foam) to 26% at-0.96 V vs. RHE, whereas methane yield is unaffected. Effects from crystalline phase distribution and copper oxide phases are ruled out as the source of enhancement through XPS and in-situ XRD analysis. DFT calculations reveal that poly(acrylamide) adsorbs on the copper surface via the oxygen atom on the carbonyl groups, and enhances ethylene formation by i) charge donation to the copper surface that activates 1

No abstract

A scalable solvothermal technique is reported for the synthesis of a photocatalytic composite material consisting of orthorhombic Ta3N5 nanoparticles and WOx≤3 nanowires. Through X-ray diffraction and X-ray photoelectron spectroscopy, the as-grown tungsten(VI) sub-oxide was identified as monoclinic W18O49. The composite material catalysed the degradation of Rhodamine B at over double the rate of the Ta3N5 nanoparticles alone under illumination by white light, and continued to exhibit superior catalytic properties following recycling of the catalysts. Moreover, strong molecular adsorption of the dye to the W18O49 component of the composite resulted in near-complete decolourisation of the solution prior to light exposure. The radical species involved within the photocatalytic mechanisms were also explored through use of scavenger reagents. Our research demonstrates the exciting potential of this novel photocatalyst for the degradation of organic contaminants, and to the authors’ knowledge the material has not been investigated previously. In addition, the simplicity of the synthesis process indicates that the material is a viable candidate for the scale-up and removal of dye pollutants on a wider scale.

Bioinspiration from hierarchical structures found in natural environments has heralded a new age of advanced functional materials. Nanocellulose has received significant attention due to the demand for high-performance materials with tailored mechanical, physical and biological properties. In this study, nanocellulose fibrils, nanocrystals and a novel mixture of fibrils and nanocrystals (blend) were prepared from softwood biomass using the AVAP® biorefinery technology. These materials were characterized using transmission and scanning electron microscopy, and atomic force microscopy. This analysis revealed a nano- and microarchitecture with extensive porosity. Notable differences included the nanocrystals exhibiting a compact packing of nanorods with reduced porosity. The NC blend exhibited porous fibrillar networks with interconnecting compact nanorods. Fourier transform infrared spectroscopy and X-ray diffraction confirmed a pure cellulose I structure. Thermal studies highlighted the excellent stability of all three NC materials with the nanocrystals having the highest decomposition temperature. Surface charge analysis revealed stable colloid suspensions. Rheological studies highlighted a dominance of elasticity in all variants, with the NC blend being more rigid than the NC fibrils and nanocrystals, indicating a double network hydrogel structure. Given these properties, it is thought that these materials show great potential in (bio)nanomaterial applications where careful control of microarchitecture, surface topography and porosity are required.

The redox potential (Eh) in a cementitious nuclear waste repository is critical to the retardation behavior of redox-sensitive radionuclides (RNs), and largely controlled by embedded steel corrosion but hard to be determined experimentally. Here, we propose an innovative Eh determination method based on chemical/spectroscopic measurements. Oxidized nuclides (U, Se, Mo, and Sb) were employed as species probes to detect the Eh values imposed by steel (Fe) and steel corrosion products (magnetite/hematite, and magnetite/goethite couples) in cement pore water. Nuclides showed good sorption affinity, especially toward Fe, in decreasing K order for U > Sb > Se > Mo under both N and H atmospheres. The reduced nuclide species were identified as UO, UO, FeSe, FeSe, Se, Sb, and SbO, but no redox transformation occurred for Mo. Eh values were obtained by using the Nernst equation. Remarkably, their values fell in a small range centered around -456 mV at pH ∼ 13.5 for both Fe and Fe-oxyhydroxides couples. This Eh value appears to be controlled by the nanocrystalline Fe(OH)/Fe(OH) or (Fe,Ca )(OH)/Fe(OH) couple, whose presence was confirmed by pair distribution function analyses. This approach could pave the way for describing the Eh gradient in reinforced concrete where traditional Eh measurements are not feasible.

We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125±18nm (PEO) and 1.58±0.28μm (PVP); Free-surface electrospun: 155±31nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8±3nm to 27±5nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique.

Hydrothermal growth of ZnO nanowires has been of great interest as it allows the use of organic substrates for flexible electronics applications. However, there are drawbacks on the growth technique as it is known to introduce defects in the nanowires. In this work, the use of intense pulsed light on hydrothermally grown ZnO nanowires on polyimide substrate was performed to enhance the physical and electronic properties of the nanomaterials. Such photonic annealing technique offers a rapid and effective improvement in material properties and importantly it is suitable for use on a wide variety of organic substrates, which are vital for flexible electronics.

ZnO nanosheets are polycrystalline nanostructures that are used in devices including solar cells and gas sensors. However, for efficient and reproducible device operation and contact behaviour the conductivity characteristics must be controlled and surface contaminants removed. Here we use low doses of argon bombardment to remove surface contamination and make reproducible lower resistance contacts. Higher doses strip the surface of the nanosheets altering the contact type from near-ohmic to rectifying by removing the donor-type defects, which photoluminescence shows to be concentrated in the near-surface. Controlled doses of argon treatments allow nanosheets to be customised for device formation.