The TiO2/MXene heterostructure has attracted considerable attention in photocatalysis owing to its high specific surface area and enhanced interfacial charge carrier separation, which significantly improves photocatalytic efficiency. In this work, Cu-doped TiO2/Ti3C2Tx MXene nanocomposites were successfully synthesized using facile solid-state method and investigated for photocatalytic dye degradation under solar irradiation. Electron microscopy confirmed a well-coupled heterostructure, with Cu–TiO2 nanoparticles uniformly anchored on MXene sheets, exhibiting lattice spacings of 0.34 nm for TiO2 (101) and 0.98 nm for Ti3C2 (002) planes. Elemental mapping and XPS analysis verified the homogeneous elemental distribution and the presence of Ti4+, lattice oxygen, Cu species, and MXene-related C–Ti bonding. UV–Vis diffuse reflectance and Tauc analysis revealed band gap narrowing from 2.63 eV (Cu–TiO2) to 2.39 eV for the optimized composite, enabling enhanced visible light absorption. The Cu–TiO2/MXene nanocomposites exhibited significantly improved photocatalytic performance, achieving up to 97.5

We present a synthesis route for solid-state nanocatalysts composed of gallium phosphide nanowire supports decorated with catalytic palladium nanoparticles. Through precise control of fabrication conditions, we were able to tune the nanowire morphology, density, and crystal structure. The resulting catalysts were highly active and selective in the partial hydrogenation of phenylacetylene to styrene. Size-selected palladium nanoparticles deposited in the aerosol form primarily settle on the upper sidewalls of tapered nanowires, retaining crystallinity and shape. Adjustable nanocatalyst fabrication conditions allow tuning of surface wettability. Hydrophobic, low-density nanocatalysts show enhanced activity in hydrogenation reactions. Exploring these fabrication parameters enables a tailored design of heterogeneous nanocatalysts and provides insights into the critical factors influencing their functionality.

Exfoliating graphene by employing electrochemical exfoliation (ECE) has emerged as a promising route for obtaining large-scale graphene material at a reasonable cost. However, in addition to the exfoliation parameters, the obtained graphene quality can strongly depend on the graphite electrode type used for exfoliation, and a proper understanding is lacking. In the current work, the impact of graphite electrode types in graphene exfoliation has been investigated. Three different commercially available graphite types, namely, graphite block, graphite foil (compressed), and synthetic graphite foil types, are explored. Electrolyte solutions of H2SO4 combined with KOH of molar concentration of 0.1 M - 3 M are used for the ECE. In the case of the graphite block, despite having an exfoliation rate of similar to 10(-3) g/min, no graphene flake was found. Compressed and synthetic type yields graphene material with a rate of 10(-3) - 10(-4) g/min, depending on the molar concentration and electrical parameter. Raman study reveals exfoliation from compressed type provides I-D/I-G of 1.06, which seems to decrease to 0.19 (lesser defect) after sonication. On the other hand, for the synthetic type, the I-D/I-G value is 1.36. The microstructural configuration of the electrode is found to play a key role in the exfoliation process, and a correlation between the two is established. The study substantially advances our understanding of the electrochemical exfoliation process of graphene. We have also proposed and demonstrated a synthesis process of graphene and holey graphene in a simultaneous fashion using a single-cell, two-compartment design that can efficiently synthesize both materials in a single step. The pores are produced via the reduction of the functionalized graphene part. The pore size can vary from a few nm to hundreds of nm, as validated by the electron microscopy and surface characterization. The demonstrated method has the potential to be scaled up and meet the industrial demand.

Day and night shift-induced thermal cycling offers a promising route toward free energy for green hydrogen production and dye degradation. Pyroelectric materials make this possible by converting temperature fluctuations into electrical charges that drive water splitting catalytic reactions and produce hydrogen fuel. Herein, we demonstrate an efficient pyrocatalytic hydrogen evolution reaction and Rhodamine B (RhB) degradation using ferroelectric potassium niobate (KNbO3) perovskite nanoplatelets (KN-np) with an orthorhombic phase. Under thermal cycling between 20 and 50 degrees C, KN-np produced a high hydrogen yield of 680 mu mol & sdot;g-1 over 30 thermal cycles, with an average hydrogen generation rate of approximately 22.67 mu mol g-1 per thermal cycle. Besides, KN-np pyrocatalytic activity enabled efficient degradation of the RhB dye up to 84 % after only 16 cycles with a high kinetic rate constant of 0.11 per thermal cycle. Our findings show that the excellent pyroelectric properties of KN-np are at the origin of the catalytic activity enhancement. This work lays the foundation for the future design of pyroelectric materials for clean energy production and environmental remediation.

This study examines the effects of annealing duration on the oxygen vacancies in gallium oxide (Ga2O3) thin films. Ga2O3 thin films were deposited by RF magnetron sputtering on (100) silicon substrates and subsequently annealed in an argon atmosphere at 1000 degrees C for 1, 2, 4, and 7 h. The impact of the annealing time on the morphology, oxygen content, optical bandgap, and thickness of Ga2O3 thin films was thoroughly investigated. All annealed films exhibited a polycrystalline (3-Ga2O3 phase with a monoclinic crystal structure and a preferred orientation along the (400) plane. Increasing the annealing time resulted in larger grains, a denser interfacial layer, and reduced microstrain. Prolonged annealing also facilitated the escape of oxygen atoms, creating oxygen vacancies that formed a defect band below the conduction band, significantly lowering the optical bandgap. Cross-sectional transmission electron microscopy revealed a Ga2O3/SiO2 heterostructure formation, with Ga2O3 thickness decreasing and SiO2 thickness increasing with longer annealing times. These findings enhance the understanding of the role of annealing in optimizing Ga2O3 thin films for electronic and optoelectronic applications.

A facile and scalable strategy is reported for green hydrogen production via pulsed electrodeposition of MoS2 quantum dots (QDs), exploiting their high surface-to-volume ratio and intrinsic catalytic activity. The synthesized QDs exhibit a mixed-phase structure comprising both the metallic 1T and semiconducting 2H polymorphs of MoS2, which synergistically promote charge carrier mobility and interfacial charge transfer while ensuring electrochemical stability under prolonged operation. Structural and compositional analyses, including X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and high-resolution transmission electron microscopy, confirm the coexistence of 1T and 2H phases. Photoelectrochemical impedance spectroscopy and photocurrent response measurements demonstrate excellent catalytic performance, with a photocurrent density of-30 mA cm-2 at-0.5 V vs. RHE, a low onset potential of 42 mV, a small Tafel slope of 90 mV center dot dec-1, and minimal overpotential requirements. Notably the 1T/2H-MoS2 QDs catalyst exhibit robust photoelectrochemical stability and achieve a high hydrogen evolution rate of 1700 mu mol L-1 center dot h-1 outperforming or matching the efficiency of state-of-the-art MoS2-based catalysts. These results position hybrid-phase MoS2 QDs as a promising next-generation electrocatalyst for efficient and sustainable hydrogen evolution applications.

The increasing demand for environmentally friendly and low‐energy consumption fabrication methods has slowed the advancement of graphene technology. In this work, a catalyst‐free method is presented for the deposition of high‐quality graphene on diverse substrates using ethylene. Through the utilization of a low‐pressure plasma‐enhanced chemical vapor deposition (PECVD) technique at ambient temperature, followed by flash annealing, it demonstrates the growth of graphene films on diverse substrates including silicon, silicon dioxide, metal foils, quartz, fluorine doped tin oxide, glass and polyamide, without the reliance on metal catalysts. The approach employs ethylene as a carbon donor free of a reducing agent, hence ensuring minimal environmental impact during the fabrication process. It also allows direct deposition on desired medium without the need for further complex transfer process. Comprehensive characterizations confirm the successful formation of graphene films with uniform thickness of 3–10 layers and with high structural integrity while showcasing a resistivity of 3.52·10 −4 Ω.cm. Thanks to its superhydrophobic nature, the graphene directly deposited onto scanning microwave microscopy tip demonstrates an improved resolution as compared to a graphene‐free tip. The eco‐friendly approach, coupled with its versatility regarding the substrate compatibility, offers promising prospects for sustainable graphene production.

Integrating ferroelectric materials into photoelectrochemical (PEC) systems is a potentially promising way of improving the efficiency of solar water splitting. Despite the growing interest in ferroelectric materials for PEC applications, achieving effective domain alignment in polycrystalline films remains a significant challenge. Unlike epitaxial or single-crystal systems, polycrystalline ferroelectrics inherently suffer from random grain orientations and intrinsic structural disorder, which limit their polarization efficiency. In this study, we develop nanostructured BiFeO3 (BFO) photoelectrodes via a low-cost spray-coating technique. We demonstrate that applying an external electric field successfully induces ferroelectric poling across the disordered polycrystalline matrix, resulting in effective dipoles alignment and a significant enhancement in PEC performance. In contrast to reported studies, our work demonstrates that ferroelectric polarization can be effectively harnessed even in undoped, polycrystalline BFO, suggesting that structural limitations associated with grain boundaries and crystallographic disorder can be overcome through external electric field poling. Specifically, polarized BFO photoelectrode with-5V bias exhibited a hydrogen production rate of 7368 mu mol L-1h-1, which is 9-fold compared to the 813 mu mol L-1h-1 yield obtained by pristine BFO. This superior performance, attributed to the alignment of ferroelectric domains, enabled efficient charge carrier separation and reduced recombination rate. Our findings underscore the beneficial effects of ferroelectric catalysts and promote photoelectrocatalysis beyond conventional semiconductor catalysts and band gap engineering, in particular by using poling as a scalable and reversible process for improving PEC performance.

We combine density functional theory simulations and sensing experiments to evaluate the gas detection performance of two transition metals dichalcogenides MoS2 and WS2. Specifically, we examine their sensitivity, detectivity, response and recovery times towards carbon dioxide (CO2), and carbon monoxide (CO). Our DFT simulations reveal remarkable sensing properties of WS2 to both CO and CO2, demonstrated by high adsorption energies of– 11.4 meV and– 12 meV respectively, compared to– 5 meV and– 0.6 meV for MoS2. Subsequently, our sensing experiments further validate the theoretical predictions, demonstrating the superior gas sensing performance of WS2 towards CO2 and CO, exhibiting high recovery and response times of 4.4 s and 9 s, for CO2 and 9 s and 18 s for CO. Our comparative study underscores the potential of WS2 and MoS2 in advancing gas sensing technologies and offers valuable insights for further developments in environmental monitoring applications.

Transdermal microneedles (MNs) have emerged as a powerful new technique for medicine and drug delivery. MNs are highly bioavailable, biocompatible, and non-invasive drug delivery systems. Catalase is one of the antioxidant enzymes that decomposes hydrogen peroxide to overcome oxidative damage. Enzymatic proteins such as catalase have a great therapeutic potential; however, their application in vivo is limited until now. For example, when they are administered orally, therapeutic proteins are easily degraded by proteases such as pepsin. In general, MNs can create micron-size channels, overcome the stratum corneum barrier, and deliver therapeutic proteins efficiently. Here, we designed hydrogel-based MNs to deliver catalase protein efficiently. For the fabrication of hydrogel-based MNs, the first step was to produce a MN master mold by using a 3D printer. The second step was to generate a polydimethylsiloxane (PDMS) mold by the reverse micro-molding technique. Next, a hydrogel solution with polyvinyl alcohol (PVA) and chitosan was optimized to produce casted hydrogel MN embraced with good mechanical properties. Among the ratio of PVA to chitosan used in the MN fabrication, the 2:1 ratio (w/w) of PVA:chitosan was the optimized composition for attaining ideal morphology and mechanical strength. Catalase was subsequently loaded onto the hydrogel MNs, and it was successfully delivered into the pig ear through passive diffusion. A longer residence time until 1 h improved the delivery of catalase that kept enzymatic activity after the delivery. Protein delivery using MNs was also strongly enhanced by external stimulations such as ethanol or ultrasound, which was known to disrupt the stratum corneum. The global market for MNs as a drug delivery system is ready to expand, and numerous applications of hydrogel-based MNs are anticipated to deliver therapeutic proteins.

Green hydrogen is a highly sought-after clean fuel for the next generation of engines aimed at achieving net-zero emissions. Herein, we design and fabricate a mixed-phase core/shell nanoparticles consisting of a semiconducting 2H-MoS2 core and a metallic 1T-MoS2 coating. The core/shell exhibits spherical morphology with an average diameter of 60 nm. To leverage this unique structure, we develop a photocathode device composed of 1T/2H-MoS2 core/shell integrated with p-type silicon to catalyze hydrogen evolution reaction via water splitting driven by solar energy. The core/shell device demonstrates, at zero bias, a remarkable current density of-13.5 +/- 1 mA/cm2 and an onset potential of 110 mV. Additionally, the device exhibited a rapid photoresponse time and a high incident photon-to-current efficiency reaching 80 % at 450 nm. Our findings highlight the synergistic effect of 1T/2H-MoS2 mixed-phase core/shell structure in developing the next generation of high-efficient photocatalysts for green hydrogen generation.

We report on the pulsed laser deposition of ultrathin MoS2 films and how their electrical conductivity is significantly sensitive to thickness variation. It is shown that the thickness of MoS2 ultrathin films can be fairly controlled over the (1.3–12.6) nm range by simply adjusting the number of incident laser ablation pulses (NLP). Noteworthy, the electrical conductivity of the MoS2 ultrathin films was found to change by more than 6 orders of magnitude, abruptly switching from semiconducting to conductive behavior, upon increasing the thickness in the nm range. Raman analyses revealed that our ultrathin films comprise both 2H and 1T phases with a clear tendency for the metallic 1T phase to increase at the expense of its 2H phase counterpart, as the film thickness is increased from 1.3 to ∼13 nm. Concomitantly, their density of defects also increases with N. Our results highlight the significant structural and electrical changes that occur in MoS2 ultrathin films as their thickness is barely increased from a few to only several layers. A direct relationship between the conductivity of the pulsed laser deposition (PLD)-MoS2 ultrathin films and their structural characteristics (both 1T-MoS2 phase content and density of defects) is established. Finally, this work paves the way for the PLD as an effective synthesis route for the controlled growth of hybrid 2H-/1T-MoS2 ultrathin films with the possibility of wafer scaling.

This Letter reports the stability of regrown and alloyed Ohmic contacts to AlGaN/GaN-on-Si high electron mobility transistors (HEMTs) for high temperature applications up to 500 degrees C. Transfer length method (TLM) measurements from 25 to 500 degrees C in air show that the regrown contacts appear to be stable up to 500 degrees C during short term (approximately 1 h) testing, while alloyed contacts appear to decrease in contact resistance from 300 to 500 degrees C though increases in the error bounds due to increase sheet resistance make it difficult to conclude definitely. Additionally, longer term testing shows both technologies remain stable at least up to 48 h at 500 degrees C, after which the large increase in sheet resistance makes the measurement uncertainty too large to conclude definitively. Advanced microscopy images indicate both the regrown and alloyed contact regions remain structurally intact after prolonged high temperature exposure with no visible degradation in crystallinity or metal composition.

Visible-light-driven photocatalysis using layered materials has garnered increasing attention regarding the degradation of organic dyes. Herein, transition-metal dichalcogenides MoS2 and WS2 prepared by chemical vapor deposition as well as their intermixing are evaluated for photodegradation (PD) of methylene blue under solar simulator irradiation. Our findings revealed that WS2 exhibited the highest PD efficiency of 67.6% and achieved an impressive PD rate constant of 6.1 × 10−3 min−1. Conversely, MoS2 displayed a somewhat lower PD performance of 43.5% but demonstrated remarkable stability. The intriguing result of this study relies on the synergetic effect observed when both MoS2 and WS2 are combined in a ratio of 20% of MoS2 and 80% of WS2. This precise blend resulted in an optimized PD efficiency and exceptional stability reaching 97% upon several cycles. This finding underscores the advantageous outcomes of intermixing WS2 and MoS2, shedding light on the development of an efficient and enduring photocatalyst for visible-light-driven photodegradation of methylene blue.

This Letter reports an investigation of hole transport in p-GaN/AlGaN/GaN heterostructures through experimental and theoretical analyses under varied conditions. Highly non-linear current–voltage (I–V) characteristics, obtained via the linear transmission line method measurements, are utilized for this study. At low bias voltage, the transport can be ascribed to the Schottky nature of the contact, while at high bias, the conduction is observed to be governed by space-charge limited current (SCLC). The Schottky characteristics (Schottky barrier height and non-ideality factor) and the SCLC exponent were analyzed for devices with varying contact spacings and at different high temperatures. The SCLC exponent, m, is in the range of 2≤m≤4 depending on the applied voltage range, revealing the existence of the trap states in the channel region. The findings of this work indicate that the charge injection, field-induced ionization, and trap states in the p-GaN channel are critical factors in the current transport of p-GaN/AlGaN/GaN heterostructure.

Optoelectronic Properties of Pulsed Laser Deposited "3D"-MoS2 Films The pulsed laser deposition technique is used by My Ali El Khakani and co-workers to grow MoS2 films with a particular microstructure where their constituting layers are vertically aligned. These relatively-thick ("3D") MoS2 films were found to behave as direct-bandgap "2D-MoS2" with exceptional optoelectronic properties. The optoelectronic properties of the films are shown to be linearly correlated to the degree of vertical alignment of MoS2 layers. This paves the way for the integration of "3D"-MoS2 films into highly photosensitive devices, compatible with VLSI-technologies.

Tung oil (TO) microcapsules (MCs) with a poly(urea-formaldehyde) (PUF) shell were synthesized via one-step in situ polymerization, with the addition of graphene nanoplatelets (GNPs) (1–5 wt. %). The synergistic effects of emulsifiers between gelatin (gel) and Tween 80 were observed, with gel chosen to formulate the MCs due to its enhanced droplet stability. SEM images then displayed an increased shell roughness of the TO-GNP MCs in comparison to the pure TO MCs due to the GNP species on the shell. At the same time, high-resolution transmission electron microscopy (TEM) images also confirmed the presence of GNPs on the outer layer of the MCs, with the stacked graphene layers composed of 5–7 layers with an interlayer distance of ~0.37 nm. Cross-sectional TEM imaging of the MCs also confirmed the successful encapsulation of the GNPs in the core of the MCs. Micromanipulation measurements displayed that the 5% GNPs increased the toughness by 71% compared to the pure TO MCs, due to the reduction in the fractional free volume of the core material. When the MCs were dispersed in an epoxy coating and applied on a metallic substrate, excellent healing capacities of up to 93% were observed for the 5% GNP samples, and 87% for the pure TO MC coatings. The coatings also exhibited excellent corrosion resistance for all samples up to 7 days, with the GNP samples offering a more strenuous path for the corrosive agents.

Endowed with intrinsic redox-rich features and superior electronic conductivities, mixed-metallic sulphides offer high prospects in electrochemical charge storage, especially in supercapacitors. Hence, their rational design and scalable preparation are of great scientific significance. Herein, we report the in-situ growth of nanostructured hybrids of NiMnS directly embedded into graphene sheets by a straightforward, scalable solid-state synthesis method. In this environment-friendly approach, the metal precursors, elemental sulphur, and graphene oxide (GO) are homogeneously mixed under ball-milling, followed by controlled thermal treatment. Incited from their unique synergistic contribution, the resulting NiMnS/G hybrids exhibit impressive electrochemical performance as a battery-type electrode in an aqueous electrolyte. The NiMnS/G hybrid electrode displayed a high specific capacity of 871.7C g- 1 at 2 A g- 1 with superior rate capability. Moreover, the asymmetric supercapacitor (ASC) device assembled based on the surface-enhanced NiMnS/G nanohybrid as the positive electrode and activated carbon (AC) as the negative electrode achieves an intriguing performance, delivering a maximum energy density of 53.4 Wh kg- 1 at a power density of 500 W kg- 1. The ASCs were successfully cycled over 10,000 cycles with 87 % capacitance retention and around 99 % Coulombic efficiency. This simple yet scalable strategy holds high promise and may pave the way for preparing other multimetallic sulphide-based hybrid electrode materials for electrochemical energy storage applications.