Controlled Fabrication of Photoactive Copper Oxide–Cobalt Oxide Nanowire Heterostructures for Efficient Phenol Photodegradation

Fabrication of oxide nanowire heterostructures with controlled morphology, interface, and phase purity is critical for high-efficiency and low-cost photocatalysis. Here, we have studied the formation of copper oxide–cobalt nanowire heterostructures by sputtering and subsequent air annealing to result in cobalt oxide (Co₃O₄)-coated CuO nanowires. This approach allowed fabrication of standing nanowire heterostructures with tunable compositions and morphologies. The vertically standing CuO nanowires were synthesized in a thermal growth method. The shell growth kinetics of Co and Co₃O₄ on CuO nanowires, morphological evolution of the shell, and nanowire self-shadowing effects were found to be strongly dependent on sputtering duration, air-annealing conditions, and alignment of CuO nanowires. Finite element method (FEM) analysis indicated that alignment and stiffness of CuO–Co nanowire heterostructures greatly influenced the nanomechanical aspects such as von Mises equivalent stress distribution and bending of nanowire heterostructures during the Co deposition process. This fundamental knowledge was critical for the morphological control of Co and Co₃O₄ on CuO nanowires with desired interfaces and a uniform coating. Band gap energies and phenol photodegradation capability of CuO–Co₃O₄ nanowire heterostructures were studied as a function of Co₃O₄ morphology. Multiple absorption edges and band gap tailings were observed for these heterostructures, indicating photoactivity from visible to UV range. A polycrystalline Co₃O₄ shell on CuO nanowires showed the best photodegradation performance (efficiency ∼50–90%) in a low-powered UV or visible light illumination with a sacrificial agent (H₂O₂). An anomalously high efficiency (∼67.5%) observed under visible light without sacrificial agent for CuO nanowires coated with thin (∼5.6 nm) Co₃O₄ shell and nanoparticles was especially interesting. Such photoactive heterostructures demonstrate unique sacrificial agent-free, robust, and efficient photocatalysts promising for organic decontamination and environmental remediation

Plasma Oxidation Kinetics of Gold Nanoparticles and Their Encapsulation in Graphene Shells by Chemical Vapor Deposition Growth

High-throughput chemical vapor deposition (CVD) growth of carbon or graphene shells encapsulating gold nanoparticles (AuNPs) is a challenge due to limited solubility of carbon in AuNPs. Such a growth is only possible by utilizing surface-oxidized AuNPs. There is a lack of fundamental understanding regarding the role of morphology and surface oxidation of AuNPs in the formation of graphene shells. Here, we studied a simple wet-chemical synthesis of AuNPs with hexadecyltrimethylammonium bromide as a surfactant and the effect of postsynthesis quenching on size, shape, and defect density of AuNPs. In the next step, plasma oxidation kinetics of AuNPs to form surface gold oxide (AuO_<i>x</i>) was studied. The surface gold oxide shell thickness was found to be independent of stoichiometry of AuO_<i>x</i> and followed the Cabrera–Mott model for oxidation kinetics. The surface-oxidized AuNPs were further utilized as catalysts for the growth of graphene shell encapsulated AuNPs (GNPs) in a xylene CVD process. The unstable surface gold oxide played a major role in the CVD process by accepting electrons from the incoming carbon feed, resulting in graphene shells around AuNPs. On the other hand, surface oxidized AuNPs with lattice defects, in a similar xylene CVD process, resulted in amorphous carbon and distorted graphene shells encapsulating AuNPs. Overall, this study reveals the mechanisms and critical factors relevant to the growth of GNPs. Such an approach for hybridizing graphene shells with AuNPs is promising for nanoelectronics and sensing

Additional file 1: of Network analysis of psoriasis reveals biological pathways and roles for coding and long non-coding RNAs

List of differentially expressed genes. The full list of genes that were differentially expressed (FDR ≤ 0.05) in (1) PPvNN and (2) PPvPT. (XLS 709 kb

Additional file 4: of Network analysis of psoriasis reveals biological pathways and roles for coding and long non-coding RNAs

List of GO and Broad MSigDB terms enriched for in the top correlated modules of PPvPT. The full list of GO and Broad MSigDB terms enriched for (p ≤ 0.005) in the sienna3 and lightyellow modules of PPvPT. (XLS 83 kb

Carbon Dioxide Hydrogenation over a Metal-Free Carbon-Based Catalyst

The hydrogenation of CO₂ into useful chemicals provides an industrial-scale pathway for CO₂ recycling. The lack of effective thermochemical catalysts currently precludes this process, since it is challenging to identify structures that can simultaneously exhibit high activity and selectivity for this reaction. Here, we report, for the first time, the use of nitrogen-doped graphene quantum dots (NGQDs) as metal-free catalysts for CO₂ hydrogenation. The nitrogen dopants, located at the edge sites, play a key role in inducing thermocatalytic activity in carbon nanostructures. Furthermore, the thermocatalytic activity and selectivity of NGQDs are governed by the doped N configurations and their corresponding defect density. The increase of pydinic N concentration at the edge site of NGQDs leads to lower initial reaction temperature for CO₂ reduction and also higher CO₂ conversion and selectivity toward CH₄ over CO

Hybrid MoS₂/h-BN Nanofillers As Synergic Heat Dissipation and Reinforcement Additives in Epoxy Nanocomposites

Two-dimensional (2D) nanomaterials as molybdenum disulfide (MoS₂), hexagonal boron nitride (h-BN), and their hybrid (MoS₂/h-BN) were employed as fillers to improve the physical properties of epoxy composites. Nanocomposites were produced in different concentrations and studied in their microstructure, mechanical and thermal properties. The hybrid 2D mixture imparted efficient reinforcement to the epoxy leading to increases of up to 95% in tensile strength, 60% in ultimate strain, and 58% in Young’s modulus. Moreover, an enhancement of 203% in thermal conductivity was achieved for the hybrid composite as compared to the pure polymer. The incorporation of MoS₂/h-BN mixture nanofillers in epoxy resulted in nanocomposites with multifunctional characteristics for applications that require high mechanical and thermal performance