Designing of high-performance, low-cost, and nonprecious metal-based bifunctional electrocatalysts are highly significant for the development of water splitting process and expanding the practical ...application of green hydrogen production. Transition metal dichalcogenides (TMDs) with intrinsic physical and chemical properties have been considered potential catalytic materials for electrode fabrication. However, it has remained challenging to develop TMD catalysts that have bifunctional properties for overall water splitting. Herein, WSe2, as a typical representative of TMDs, was utilized to design electrocatalysts using polypyrrole (PPy) or polyaniline (PANI) as a conducting polymer (CP) and cobalt doping. A facile hydrothermal preparation of WSe2 in the presence of CP enabled the construction of cobalt-doped WSe2@CP electrocatalysts. Morphological analysis indicated that the CP played an important role as a conductive template to enhance the distribution of WSe2 nanosheets, leading to higher surface area. In addition, cobalt doping led to the formation of defect structures and boosted the electrocatalytic activities of the catalysts for oxygen evolution reaction (OER). Owing to the increased electrochemical surface area and defects structures, the cobalt-doped WSe2@CP nanostructures exhibited enhanced electrochemical properties for hydrogen evolution reaction (HER) and OER in an alkaline medium. The cobalt-doped WSe2@PANI modified glassy carbon electrode (GCE) exhibited overpotentials down to 308 and 360 mV at a current density of 10 mA cm-2 for the HER and OER, respectively. Furthermore, the cobalt-doped WSe2@CP electrocatalysts demonstrated long-term stability and continuous cycling. More importantly, the Co-WSe2@PANI electrolyzer required cell voltage of 1.87 V at a current density of 10 mA cm-2 for overall water splitting process. This work provides new findings for designing efficient bifunctional electrocatalysts utilizing TMD materials and conducting polymers.
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•Conducting polymer templated and cobalt-doped WSe2 electrocatalysts were prepared.•Conducting polymers enhanced the catalytic performance of WSe2 in water splitting.•Incorporation of cobalt enhanced the activity of WSe2 for both HER and OER.•New WSe2-based catalysts have bifunctional activities for overal water splitting.
This study presents the development and characterization of a nanocomposite material, consisting of thermoplastic starch (TPS) reinforced with bentonite clay (BC) and encapsulated with vitamin B2 ...(VB). The research is motivated by the potential of TPS as a renewable and biodegradable substitute for petroleum-based materials in the biopolymer industry. The effects of VB on the physicochemical properties of TPS/BC films, including mechanical and thermal properties, water uptake, and weight loss in water, were investigated. In addition, the surface morphology and chemical composition of the TPS samples were analyzed using high-resolution SEM microscopy and EDS, providing insight into the structure-property relationship of the nanocomposites. The results showed that the addition of VB significantly increased the tensile strength and Young's modulus of TPS/BC films, with the highest values observed for nanocomposites containing 5 php of VB and 3 php of BC. Furthermore, the release of VB was controlled by the BC content, with higher BC content leading to lower VB release. These findings demonstrate the potential of TPS/BC/VB nanocomposites as environmentally friendly materials with improved mechanical properties and controlled release of VB, which can have significant applications in the biopolymer industry.
We have designed and verified a new structure for ohmic contacts to p-GaN based on a layer of carbon nanotubes (CNT), reduced graphene oxide (r-GO) and metallic layers of Cr, Pd and Au, namely in ...configurations Au/Cr/r-GO/CNT/p-GaN and Au/Pd/r-GO/CNT/p-GaN. The effects have been studied of the annealing temperature and the gas ambient upon the electrical properties of the contacts. Annealing of the Au/Pd/r-GO/CNT/p-GaN structure in air at 500°C for 1 minute resulted in linear
curves measured between planar electrodes on the p-GaN. Hence, addition of r-GO to the CNT interlayer between p-GaN and the metallization layer is a highly promising procedure for further improvements of the ohmic contacts to p-GaN.
Boron doped diamond (BDD) has remarkable physical and chemical properties, that makes it an attractive material for electrochemical applications. In this study, deposition process of BDD on porous ...carbon foam electrodes was performed by HFCVD method. After depositions, the substrates were not homogenously covered by the BDD thin film only. Depending on the deposition temperature, foam porosity and distance from heated filaments, different carbon nanomaterials were synthesized. The boron doped diamond, graphite nanosheets, carbon nanowalls and its composites occurred on the foams outer and inner surfaces. Two new observed types of carbon structures, the carbon nanowalls - boron doped diamond composite and graphite nanotips are analyzed and described. Analyses were made by SEM and Raman spectroscopy. The influence of deposition conditions on the growth process is discussed.
Ptex is a texture mapping method. It’s main advantage is the elimination of UV mapping process by storing separate texture for each face. Ptex deals with the filtering across face boundaries, which ...makes all the little separate textures look seamless, as if they were one big texture. Ptex file format can efficiently store hundreds of thousands of images into a single file. Ptex API is released as open source, written in C++, which enables implementation of Ptex in various programs. This paper analyses advantages and drawbacks of this system and examines if Ptex is today usable outside of big production studios. Analysis leads us to a conclusion that Ptex can already be used by individuals outside of big production studios.
Due to their properties, carbon nanotubes and reduced graphene oxide are highly promising materials for obtaining low-resistance ohmic contacts to p-GaN with good optical transparency for visible ...light. In this contribution we designed a combination of these two materials, along with a cap layer, to be used as structures for ohmic contacts to p-GaN. Carbon nanotube (CNT) and graphene oxide (GO) layers were deposited by spray coating using an off-the-shelf airbrush on p-GaN layers. The metallic layers of Au/Pd were vapour deposited. The structures for ohmic contacts were prepared in two configurations, namely as Au/Pd/r-GO/CNT/p-GaN and Au/Pd/CNT/r-GO/CNT/p-GaN. The prepared structures provide a low resistivity ohmic contact after subsequent annealing in air ambient at 600 °C for 3 minutes. The contact containing the sandwich CNT/r-GO/CNT interstructure exhibits lower values of contact resistance in comparison with the r-GO/CNT interstructure.
Few-layer MoS2 films stay at the forefront of current research of two-dimensional materials. At present, continuous MoS2 films are prepared by chemical vapor deposition (CVD) techniques. Herein, we ...present a cost-effective fabrication of the large-area spatially uniform films of few-layer MoS2 flakes using a modified Langmuir–Schaefer technique. The compression of the liquid-phase exfoliated MoS2 flakes on the water subphase was used to form a continuous layer, which was subsequently transferred onto a submerged substrate by removing the subphase. After vacuum annealing, the electrical sheet resistance dropped to a level of 10 kΩ/sq, being highly competitive with that of CVD-deposited MoS2 nanosheet films. In addition, a consistent fabrication protocol of the large-area conductive MoS2 films was established. The morphology and electrical properties predetermine these films to advanced detecting, sensing, and catalytic applications. A large number of experimental techniques were used to characterize the exfoliated few-layer MoS2 flakes and to elucidate the formation of the few-layer MoS2 Langmuir film.
We have examined new structures for ohmic contacts to p-GaN, mainly for applications in light emitting devices, based on a layer of single-walled carbon nanotubes (SWCNT) and metallic layers of ...Au/Cr, Au/Ni-Mg(-O) namely in configurations Au/Cr/SWCT/p-GaN and Au/Ni-Mg(-O)/SWCT/p-GaN. The layer of carbon nanotubes was deposited on p-GaN by spraying a solution of synthesized SWCTs, the layers of Au/Cr were vapor deposited and the layers of Au/Ni-Mg(-O) were deposited by DC reactive magnetron sputtering in an atmosphere with and without a low concentration of oxygen (approx. 0.2at%). It has been found that the contact structures provide a low resistivity ohmic contact after subsequent annealing in N2 ambient at 700 degree C for 1min. It has also been found that the structure containing the SWCNT interlayer exhibits lower values of contact resistance in comparison with an otherwise identical contact without the SWCNT interlayer.
Inimitable properties of carbon quantum dots as well as a cheap production contribute to their possible application in biomedicine especially as antibacterial and antibiofouling coatings. Fluorescent ...hydrophobic carbon quantum dots are synthesized by bottom-up condensation method and used for deposition of uniform and homogeneous Langmuir–Blodgett thin films on different substrates. It is found that this kind of quantum dots generates singlet oxygen under blue light irradiation. Antibacterial and antibiofouling testing on four different bacteria strains (Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Pseudomonas aeruginosa) reveals enhanced antibacterial and antibiofouling activity of hydrophobic carbon dots thin films under blue light irradiation. Moreover, hydrophobic quantum dots show noncytotoxic effect on mouse fibroblast cell line. These properties enable potential usage of hydrophobic carbon quantum dots thin films as excellent antibacterial and antibiofouling coatings for different biomedical applications.
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