Continuous flow removal of acid fuchsine by dielectric barrier discharge plasma water bed enhanced by activated carbon adsorption

Continuous processes which allow for large amount of wastewater to be treated to meet drainage standards while reducing treatment time and energy consumption are urgently needed. In this study, a dielectric barrier discharge plasma water bed system was designed and then coupled with granular activated carbon (GAC) adsorption to rapidly remove acid fuchsine (AF) with high efficiency. Effects of feeding gases, treatment time and initial concentration of AF on removal efficiency were investigated. Results showed that compared to the N2 and air plasmas treatments, O2 plasma processing was most effective for AF degradation due to the strong oxidation ability of generated activated species, especially the OH radicals. The addition of GAC significantly enhanced the removal efficiency of AF in aqueous solution and shorten the required time by 50%. The effect was attributed to the ability of porous carbon to trap and concentrate the dye, increasing the time dye molecules were exposed to the plasma discharge zone, and to enhance the production of OH radicals on/in GAC to boost the degradation of dyes by plasma as well as in situ regenerate the exhausted GAC. The study offers a new opportunity for continuous effective remediation of wastewater contaminated with organic dyes using plasma technologies.     

Effect of gas pressure on electron field emission from carbon nanotube forests

This article quantifies the effect of the operating pressure of the H2 + C2H4 gas mixture on the current density and threshold voltage of the electron emission from dense forests of multiwalled carbon nanotubes synthesized using thermal catalytic Chemical Vapor Deposition under near atmospheric pressure process conditions. The results suggest that in the pressure range of interest 400-700 Torr the field emission properties can be substantially improved by operating the process at lower gas pressures when the nanostructure aspect ratios are higher. The obtained threshold voltage approximately 1.75 V/microm and the emission current densities approximately 10 mA/cm2 offer competitive advantages compared with the results reported by other authors.     

Single-step,rapid low-temperature synthesis of Si quantum dots embedded in an amorphous SiC matrix in high-density reactive plasmas

A simple, effective and innovative approach based on low-pressure, thermally nonequilibrium, high-density inductively coupled plasmas is proposed to rapidly synthesize Si quantum dots (QDs) embedded in an amorphous SiC (a-SiC) matrix at a low substrate temperature and without any commonly used hydrogen dilution. The experimental results clearly demonstrate that uniform crystalline Si QDs with a size of 3–4 nm embedded in the silicon-rich (carbon content up to 10.7at.%) a-SiC matrix can be formed from the reactive mixture of silane and methane gases, with high growth rates of ～1.27–2.34 nm s^?1 and at a low substrate temperature of 200 °C. The achievement of the high-rate growth of Si QDs embedded in the a-SiC without any commonly used hydrogen dilution is discussed based on the unique properties of the inductively coupled plasma-based process. This work is particularly important for the development of the all-Si tandem cell-based third generation photovoltaic solar cells.     

Inhomogeneous plastic straining of iron based amorphous alloys

Anisotropic plastic straining has been observed in iron based amorphous alloys. This phenomenon is explained proceeding from the notions about internal stresses in amorphous metal ribbons.     

Influence of Thermal Treatment on Inhomogeneous Plastic Deformation of Rolled Amorphous Strips of Iron-Based Alloys

The effect of thermal treatment on the character of the development of shear bands near the concentrator of stresses in iron-based amorphous alloys has been studied. It was found that rolling facilitates a decrease of the temperature at which inhomogeneous plasticity of the condensed system that does not possess a long-range order disappears; as loading on the indentor increases, the number of semiring-type shear bands in the rolled specimens decreases, with the number and length of the beam-type shear bands being larger than in the original materials.     

In Situ Formation of Oxygen Vacancies Achieving Near-Complete Charge Separation in Planar BiVO4 Photoanodes

Despite a suitable bandgap of bismuth vanadate (BiVO₄) for visible light absorption, most of the photogenerated holes in BiVO₄ photoanodes are vanished before reaching the surfaces for oxygen evolution reaction due to the poor charge separation efficiency in the bulk. Herein, a new sulfur oxidation strategy is developed to prepare planar BiVO₄ photoanodes with in situ formed oxygen vacancies, which increases the majority charge carrier density and photovoltage, leading to a record charge separation efficiency of 98.2% among the reported BiVO₄ photoanodes. Upon loading NiFeO_x as an oxygen evolution cocatalyst, a stable photocurrent density of 5.54 mA cm⁻² is achieved at 1.23 V versus the reversible hydrogen electrode (RHE) under AM 1.5 G illumination. Remarkably, a dual-photoanode configuration further enhances the photocurrent density up to 6.24 mA cm⁻², achieving an excellent applied bias photon-to-current efficiency of 2.76%. This work demonstrates a simple thermal treatment approach to generate oxygen vacancies for the design of efficient planar photoanodes for solar hydrogen production.     

Minimizing the Gibbs-Thomson effect in the low-temperature plasma synthesis of thin Si nanowires

An advanced combination of numerical models, including plasma sheath, ion- and radical-induced species creation and plasma heating effects on the surface and within a Au catalyst nanoparticle, is used to describe the catalyzed growth of Si nanowires in the sheath of a low-temperature and low-pressure plasma. These models have been used to explain the higher nanowire growth rates, low-energy barriers, much thinner Si nanowire nucleation and the less effective Gibbs-Thomson effect in reactive plasma processes, compared with those of neutral gas thermal processes. The effects of variation in the plasma sheath parameters and substrate potential on Si nanowire nucleation and growth have also been investigated. It is shown that increasing the plasma-related effects leads to decreases in the nucleation energy barrier and the critical nanoparticle radius, with the Gibbs-Thomson effect diminished, even at low temperatures. The results obtained are consistent with available experimental results and open a path toward the energy- and matter-efficient nucleation and growth of a broad range of one-dimensional quantum structures.     

Multifunctional Three‐Dimensional T‐Junction Graphene Micro‐Wells: Energy‐Efficient,Plasma‐Enabled Growth and Instant Water‐Based Transfer for Flexible Device Applications

The “third‐generation” 3D graphene structures, T‐junction graphene micro‐wells (T‐GMWs) are produced on cheap polycrystalline Cu foils in a single‐step, low‐temperature (270 °C), energy‐efficient, and environment‐friendly dry plasma‐enabled process. T‐GMWs comprise vertical graphene (VG) petal‐like sheets that seemlessly integrate with each other and the underlying horizontal graphene sheets by forming T‐junctions. The microwells have the pico‐to‐femto‐liter storage capacity and precipitate compartmentalized PBS crystals. The T‐GMW films are transferred from the Cu substrates, without damage to the both, in de‐ionized or tap water, at room temperature, and without commonly used sacrificial materials or hazardous chemicals. The Cu substrates are then re‐used to produce similar‐quality T‐GMWs after a simple plasma conditioning. The isolated T‐GMW films are transferred to diverse substrates and devices and show remarkable recovery of their electrical, optical, and hazardous NO₂ gas sensing properties upon repeated bending (down to 1 mm radius) and release of flexible trasparent display plastic substrates. The plasma‐enabled mechanism of T‐GMW isolation in water is proposed and supported by the Cu plasma surface modification analysis. Our GMWs are suitable for various optoelectronic, sesning, energy, and biomedical applications while the growth approach is potentially scalable for future pilot‐scale industrial production.     

Plasma-Enabled Graphene Quantum Dot Hydrogels as Smart Anticancer Drug Nanocarriers

One of the major challenges on the way to low-cost, simple, and effective cancer treatments is the lack of smart anticancer drug delivery materials with the requisite of site-specific and microenvironment-responsive properties. This work reports the development of plasma-engineered smart drug nanocarriers (SDNCs) containing chitosan and nitrogen-doped graphene quantum dots (NGQDs) for drug delivery in a pH-responsive manner. Through a customized microplasma processing, a highly cross-linked SDNC with only 4.5% of NGQD ratio can exhibit enhanced toughness up to threefold higher than the control chitosan group, avoiding the commonly used high temperatures and toxic chemical cross-linking agents. The SDNCs demonstrate improved loading capability for doxorubicin (DOX) via π–π interactions and stable solid-state photoluminescence to monitor the DOX loading and release through the Förster resonance energy transfer (FRET) mechanism. Moreover, the DOX loaded SDNC exhibits anticancer effects against cancer cells during cytotoxicity tests at minimum concentration. Cellular uptake studies confirm that the DOX loaded SDNC can be successfully internalized into the nucleus after 12 h incubation period. This work provides new insights into the development of smart, environmental-friendly, and biocompatible nanographene hydrogels for the next-generation biomedical applications.     

Non-thermal plasma enhances performances of biochar in wastewater treatment and energy storage applications

Surface functionalization or modification to introduce more oxygen-containing functional groups to biochar is an effective strategy for tuning the physicochemical properties and promoting follow-up applications. In this study, non-thermal plasma was applied for biochar surface carving before being used in contaminant removal and energy storage applications. The results showed that even a low dose of plasma exposure could introduce a high number density of oxygen-functional groups and enhance the hydrophilicity and metal affinity of the pristine biochar. The plasma-treated biochar enabled a faster metal-adsorption rate and a 40% higher maximum adsorption capacity of heavy metal ion Pb²⁺. Moreover, to add more functionality to biochar surface, biochar with and without plasma pre-treatment was activated by KOH at a temperature of 800 °C. Using the same amount of KOH, the plasma treatment resulted in an activated carbon product with the larger BET surface area and pore volume. The performance of the treated activated carbon as a supercapacitor electrode was also substantially improved by>30%. This study may provide guidelines for enhancing the surface functionality and application performances of biochar using non-thermal-based techniques.