Search Results (1,024)

Semiconductor-based photocatalytic water splitting is a promising pathway for sustainable hydrogen production; however, the reported performance depends not only on the intrinsic properties of the photocatalyst but also on reactor configuration and operating conditions. This systematic technical review examines the interplay between nanostructured semiconductor photocatalysts and the principal engineering variables governing photocatalytic hydrogen evolution. Particular attention is given to particle size, morphology, surface area, defect density, heterojunction design, cocatalyst incorporation, aggregation, and catalyst immobilization, as well as their interaction with reactor geometry, optical path length, photon distribution, catalyst loading, working volume, pH, sacrificial agents, mixing, thermal control, gas purging, and product quantification. The reviewed evidence indicates that these material and reactor parameters jointly determine light absorption, charge-carrier separation and transfer, suspension turbidity, mass transport, catalyst recovery, stability, and the measured hydrogen evolution rate. Batch slurry reactors remain the most widely used laboratory configuration, whereas annular, flat-panel, microreactor, fixed-bed, continuous-flow, and photofluidized systems offer specific advantages for photon utilization, catalyst reuse, product removal, and scale-up. The review also emphasizes the need to distinguish overall water splitting from sacrificial-agent-assisted hydrogen evolution. Standardized reporting of photocatalyst properties, irradiance, spectral distribution, illuminated area, reactor dimensions, reaction atmosphere, and gas-analysis procedures is essential to improve reproducibility and enable reliable comparisons among nanostructured photocatalytic systems. Full article

The clinical translation of nucleic acids is severely hindered by multiple delivery barriers, such as enzymatic degradation, poor cellular uptake, endosomal entrapment, and rapid systemic clearance. Despite the remarkable therapeutic potential of these agents, conventional delivery systems often fail to address these challenges. Lipid nanoparticles (LNPs) have emerged as a versatile platform to overcome these obstacles, offering tunable physicochemical properties, high encapsulation efficiency, and pH-responsive endosomal escape. This review summarizes recent advances in LNP-based respiratory and gastrointestinal mucosal delivery of nucleic acids, with emphasis on formulation strategies for overcoming mucus and epithelial barriers. To overcome mucosal barriers, LNP studies have shown that keeping particle size below the local mucus mesh size (~100 nm), tuning surface charge toward near-neutrality via pH-responsive ionizable lipids, and maintaining a neutral, deformable, moderately PEGylated surface during the mucin transport stage can increase transmucosal diffusivity several-fold over conventional cationic LNPs. We further discuss current limitations and propose future directions, emphasizing the need for the integration of the pathological and physiological characteristics of specific mucosa with artificial intelligence (AI) platforms to develop intelligent and personalized delivery platforms with “spatiotemporal adaptive” capabilities. Full article

Graphene nanoplatelets (GnPs) exhibit exceptional properties for advanced functional applications; nevertheless, their effective utilization is critically limited by agglomeration and poor dispersion. The incorporation of polycarboxylate-based superplasticizers (SPs) enables improved dispersion yet simultaneously introduces insulating effects that hinder conductive network formation. In the present article, we systematically investigate the interplay between GnPs and an SP under varying ultrasonic energy inputs to optimize dispersion and electrical performance through low-cost suspension processing. Dielectric measurements identify the key parameters governing conductive network formation and reveal the dual role of the SP as both dispersant and electrical barrier. Electrochemical impedance spectroscopy, combined with optical microscopy, provides further insights into the state of dispersion and charge-transport behaviour of the suspensions. For the first time, a wide range of SP and GnP concentrations were systematically analysed in terms of electrical properties. The proposed methodology provides a robust and facile approach for on-site characterization of aqueous suspensions with varying GnPs and SP concentrations. Furthermore, an equivalent circuit model is developed to quantitatively validate the experimental results, offering deeper insights into the underlying conduction mechanisms. GnP concentrations of 0.15, 0.50 and 1.00 wt.% were investigated at varying ratios of SP to GnP (0, 1, 2, 4, and 8). Dispersions without SP addition require ultrasonication up to 80 kJ for the GnP agglomerates to break. SP addition at a quantity equal to GnPs (SP1) reduces the amount of appropriate ultrasonic energy for creating a conductive network up to 65 kJ and even more (SP2) at 45 kJ. The fourfold (SP4) and eightfold (SP8) ratio of SP to GnP require higher ultrasonic energy, up to 82 kJ and 70 kJ, accordingly. Full article

Background: Osteoarthritis (OA), affecting approximately 240 million people worldwide, currently lacks targeted, long-acting therapeutic options. This study investigates how physicochemical properties (i.e., size, surface charge, polydispersity) influence poly(lactic-co-glycolic acid) (PLGA) microsphere (MS) diffusion into articular cartilage for enhanced corticosteroid delivery. Methods: PLGA MSs were synthesized via oil/water emulsions to create a variety of sizes and surface charges. MSs were loaded with corticosteroid (H-17-B) and release kinetics were studied in vitro and analyzed via HPLC. Diffusion of the MSs was investigated via a bovine explant model. Results: Unmodified PLGA MSs (approximately 0.58–0.98 µm) were synthesized via single-stage oil/water emulsion with varying poly(vinyl alcohol) concentrations and sonication intensities. All formulations exhibited near-neutral surface charges (−0.27 to 4.28 mV). Smaller particles achieved greater cartilage penetration, with bi-exponential diffusion models (R² = 0.706–0.999) outperforming classical Fickian approaches. However, multi-timepoint validation demonstrated fundamentally non-diffusive transport, likely governed by steric exclusion from the dense collagen network (0.05–0.06 µm pore size). Surface functionalization with avidin/palmitic acid or polyethylene glycol (PEG)/biotin yielded microspheres with controlled properties (0.36–0.97 µm; PDI: 0.10–0.32). In vitro release studies with hydrocortisone-17-butyrate (H-17-B; encapsulation efficiency of 79.8% ± 4.8%) demonstrated biphasic kinetics best fit by bi-exponential models (R² > 0.95). Unmodified microspheres exhibited 7.1% cumulative release by Day 14. High-performance liquid chromatography revealed that H-17-B undergoes ester hydrolysis to hydrocortisone during release, with surface modifications significantly affecting drug stability. Specifically, PEGylated microspheres maintained 96% of the drug in H-17-B form at Day 14 compared to only 37% for unmodified particles. Release was governed by PLGA degradation with concentration-independent kinetics, enabling predictable dose scalability. Conclusions: This work establishes that the behavior of PLGA microspheres in cartilage is controlled by size, charge, and surface functionalization. Surface modifications overcome physical barriers while stabilizing the encapsulated corticosteroid against premature hydrolysis, providing a framework for designing intra-articular drug delivery systems for osteoarthritis treatment. Full article

Two-dimensional electron gases (2DEGs) at complex oxide interfaces have emerged as a promising platform for next-generation oxide semiconductor devices, owing to their tunable electronic properties and rich interfacial phenomena. In this work, a LaAlO₃/SrTiO₃/LaTiO₃ (LAO/STO/LTO) trilayer heterostructure is proposed and theoretically investigated using a self-consistent Schrödinger–Poisson framework to examine the effects of multi-interface engineering on quantum confinement and carrier transport. The proposed architecture combines polar-discontinuity-driven electronic reconstruction at the LAO/STO interface with charge-transfer-induced electron accumulation at the STO/LTO interface, forming two coupled 2DEG channels within the SrTiO₃ layer. Compared with conventional single-interface oxide heterostructures, the coupled-interface configuration significantly enhances sheet carrier density and electrical conductivity, with predicted carrier densities approaching 10¹⁴ cm⁻² and gate-tunable conductivities in the range of 10³–10⁴ S cm⁻¹ under idealized operating conditions. The effects of layer thickness, gate bias, temperature, and electrostatic coupling are systematically investigated to establish practical design guidelines for optimizing carrier confinement and transport. A sensitivity analysis incorporating interface trap densities up to 2 × 10¹³ cm⁻² demonstrates that more than 60% of the ideal carrier population is retained under moderate defect concentrations, confirming the robustness of the proposed multi-interface strategy. Although the analytical model represents an upper-bound framework, its predictions are discussed in the context of experimentally relevant limitations, including interface roughness, oxygen vacancies, carrier trapping, and defect-induced scattering. Overall, the proposed LAO/STO/LTO heterostructure provides a predictive framework for engineering high-density, electrically tunable oxide 2DEGs for future nanoelectronic, terahertz, photonic, and energy-related applications. Full article

Understanding mass transport of structurally different drugs within ionically crosslinked hydrogel networks remains an important challenge in polymer-based delivery systems. In this study, hydrophilic amoxicillin (AMOX) and amphiphilic doxycycline (DOX) were encapsulated into calcium–alginate beads, respectively. A three-factor and three-level Box–Behnken design was utilized to examine the influences of alginate concentration (2–5%, w/v), CaCl₂ concentration (1–3%, w/v), and gelation time (15–45 min) on encapsulation efficiency (EE). EE exhibited considerable variability for both AMOX (10–86%) and DOX (10–63%). Optimal EE values were achieved at almost 3.5% alginate and 3% CaCl₂. The optimized gelation times differed between AMOX (45 min) and DOX (15 min), which is likely associated with differences in their physicochemical properties, although additional intermediate gelation times could further refine the optimal conditions. ANOVA identified CaCl₂ concentration and the quadratic effect of alginate as the most influential parameters. Furthermore, both models demonstrated robust predictive capability (R² > 0.98). In vitro release experiments demonstrated minimal drug diffusion in simulated gastric fluid (SGF) and significantly accelerated release in simulated intestinal fluid (SIF). These findings indicate a pH-responsive release behavior under simulated gastrointestinal conditions. The release profile was best represented by Higuchi and Korsmeyer–Peppas kinetic models. SEM and optical microscopy revealed uniform spherical beads with drug-dependent microstructural differences: hydrophilic AMOX produced smoother, wrinkled surfaces, whereas amphiphilic DOX induced localized cracking and heterogeneous microdomains. Furthermore, DLS and zeta potential measurements of the released fractions indicated nanoscale particle populations (≈190–225 nm) with moderate negative surface charge (≈−21 mV), suggesting stable colloidal dispersion during intestinal-phase release. Full article

This study investigated the effects of precursor type, NaOH molarity, and thermal curing temperature on the performance of geopolymer mortars produced using fly ash (FA), ground granulated blast-furnace slag (GBFS), metakaolin (MK), and waste brick powder (WBP). Mortars were activated using 12 M and 16 M NaOH solutions at a constant Na₂SiO₃/NaOH ratio and thermally cured at 60 and 90 °C for 24 h. Physical, mechanical, transport, microstructural, and cost-performance properties were evaluated. The results demonstrated that the optimum activation conditions strongly depended on precursor type. MK-based mortars cured at 16 M–90 °C exhibited the best overall performance, achieving the lowest apparent porosity (6.1%) and water absorption (5.4%), and the highest oven-dry density (2194 kg/m³), compressive strength (25.8 MPa), and flexural strength (3.43 MPa). These mortars also exhibited the lowest capillary water absorption (1.88 kg/m²), the highest electrical resistivity (248.00 kΩ·cm), and the lowest charge passed (177 C), indicating enhanced pore refinement and chloride-ion penetrability. In contrast, GBFS performed better under milder activation conditions, whereas WBP showed lower performance due to its coarser, more crystalline structure. SEM/EDS analyses confirmed that the formation of dense aluminosilicate gel governed matrix quality and overall performance. Overall, MK activated at 16 M and cured at 90 °C provided the most favorable balance between technical performance and cost efficiency. Full article

In this work, split-gate (SG) AlGaN/GaN heterostructure field-effect transistors (HFETs) with different gap angles were fabricated. The effect of the gap angle on the transport characteristics of these SG devices was investigated via measurement and analysis of their direct-current electrical properties. The results show that varying the gap angle significantly influences the channel current and further modulates the turn-off voltage of the devices. Theoretical analysis indicated that a change in gap angle directly alters the length of the gap region and affects the conduction channel effective width (Weff) through geometric effects, thereby modifying the channel current. In addition, the gap angle affects the total amount and distribution of additional polarization charges underneath the gate, which influences the polarization Coulomb field (PCF) scattering intensity and thus modulates the electron mobility of the devices. These findings provide a new direction for the structural optimization of SG AlGaN/GaN HFETs and offer a valuable reference for further improving the performance of SG devices. Full article

In this study, the effect of Ti content on the electrochemical behavior and passive film growth mechanism of Ni₅₀Nb_50−xTi_x (x = 10, 15, and 20 at.%) metallic glasses produced via melt spinning was investigated. Structural characterization via X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the fully glassy nature and chemical homogeneity of all alloys. Electrochemical performance was evaluated in a 3.5 wt.% NaCl solution using potentiodynamic and potentiostatic polarization, as well as electrochemical impedance spectroscopy (EIS). The results showed that increasing Ti content improves corrosion resistance by reducing corrosion and passive current densities and increasing charge-transfer resistance. The Ni₅₀Nb₃₀Ti₂₀ alloy exhibited the best electrochemical performance, associated with the formation of a more stable and protective passive film. The passive film growth mechanism was analyzed using the High-Field Model (HFM). A linear relationship between inverse capacitance and anodic potential confirmed that ionic transport through the oxide layer governs passive film growth. The calculated electric field strength decreased systematically with increasing Ti content, suggesting the formation of passive films with lower defect density and enhanced barrier properties. These results demonstrate that adding Ti significantly enhances the passivation behavior of Ni-Nb metallic glasses and promotes the formation of stable oxide films with improved corrosion resistance in chloride-containing environments. Full article

Rechargeable zinc–air batteries (ZABs) are attractive energy storage systems owing to their high theoretical energy density, intrinsic safety, and low cost. Yet, their practical deployment is hindered by parasitic hydrogen evolution reaction (HER), zinc corrosion, and poor interfacial stability in alkaline electrolytes. Herein, biomass-derived carbon quantum dots (CQDs) synthesised from lemon peel waste via a hydrothermal route were employed as multifunctional electrolyte additives to regulate the zinc/electrolyte interface and mitigate these challenges. The CQDs exhibited oxygen-rich surface functionalities and quasi-spherical nanoscale morphology, enabling stable dispersion in 6 M KOH. Electrolyte modification with CQDs significantly altered the physicochemical properties of the electrolyte, increasing the zeta potential from −28.2 to +48.5 mV while maintaining high ionic conductivity. Electrochemical studies demonstrated progressive suppression of HER, evidenced by a shift in HER onset potential from 146 to 291 mV, an increase in overpotential at 10 mA cm⁻² from 398 to 477 mV, and an increase in Tafel slope from 82 to 130 mV dec⁻¹. Corrosion studies revealed enhanced zinc stability, with the charge transfer resistance increasing from 1.35 to 3.80 Ω and a maximum corrosion inhibition efficiency of 64.47% achieved at an optimal CQD loading of 1.0 mg. Furthermore, the CQD-modified electrolyte improved the average operating power density of the ZAB from approximately 4.5 to 5.5 mW cm⁻² and reduced charge–discharge polarisation during cycling. The enhanced performance is attributed to a combination of surface-controlled and transport-related processes, whereby oxygen-functionalized CQDs modify the electrical double layer, retard HER kinetics, and inhibit zinc corrosion. This work demonstrates a sustainable electrolyte engineering strategy for improving the durability and electrochemical performance of ZABs using biomass-derived carbon quantum dots. Full article

Nanostructured Co₃O₄ was synthesized via a sol–gel approach employing the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate ([EMIm]TfO) and subsequently evaluated as a high-performance anode material for lithium-ion batteries. Ionic liquids, distinguished by their low volatility, high thermal stability, and tunable chemical properties, represent a greener alternative to conventional organic solvents for the synthesis of functional nanomaterials. The electrochemical performance of the as-prepared material was systematically assessed through galvanostatic charge–discharge cycling, cyclic voltammetry, and rate capability tests. The Co₃O₄ electrode exhibited a high reversible capacity of approximately 1100 mAh g⁻¹ after 50 cycles at a current density of 200 mA g⁻¹, along with excellent coulombic efficiency approaching ~100% after the initial cycles. Furthermore, the material demonstrated strong rate capability, delivering about 600 mAh g⁻¹ at 1 C, and recovering its capacity upon returning to lower current densities. The improved electrochemical performance is primarily attributed to the nanoscale architecture induced by the ionic liquid-assisted synthesis, which facilitates rapid lithium-ion transport and effectively buffers volume variations during repeated cycling. Notably, the ionic liquid serves a dual function as both a green reaction medium and a structure-directing agent, enabling precise control over the material’s morphology and properties. This study demonstrates a versatile strategy for the rational design of potential transition-metal oxide anodes, paving the way for high-performance electrode materials. The findings contribute to the development of next-generation lithium-ion batteries tailored for clean and sustainable energy storage applications. Full article

Biomass-derived porous carbons are promising supercapacitor electrodes, but their electrochemical performance is often limited by the trade-off between activation-induced pore formation and heteroatom retention. In this work, algae biomass was used as an intrinsic N/O/S-containing precursor to prepare self-nitrogen-doped hierarchical porous carbon by pre-carbonization followed by controlled KOH activation. A temperature-, dosage- and time-dependent sample library was constructed to correlate activation conditions with textural properties, nitrogen configuration, wettability, charge-transfer resistance and electrochemical behavior. The optimized AHPC-850 sample exhibits a BET surface area of 1486 m² g⁻¹, a total pore volume of $0.96$ cm³ g⁻¹, a retained surface nitrogen content of 2.91 at.%, and a charge-transfer resistance of $0.41$$\Omega$. In a three-electrode configuration, AHPC-850 delivers 386 F g⁻¹ at 1 A g⁻¹ and retains 62.4% of its capacitance at 20 A g⁻¹. During 10,000 cycles at 10 A g⁻¹, the electrode maintains 96.3% capacitance retention with a stable coulombic efficiency above 98.8%. A symmetric aqueous device based on AHPC-850 achieves an energy density of $24.8$ Wh kg⁻¹ at 250 W kg⁻¹. These results indicate that algae-derived carbon can be improved by balancing pore accessibility, nitrogen retention and transport resistance rather than by maximizing surface area alone. Full article

Dye-sensitized solar cells (DSSCs) remain promising low-cost photovoltaic technologies because of their simple fabrication, tunable optical properties, and effective operation under low-light conditions. Titanium dioxide (TiO₂) is the most widely used photoanode material in DSSCs owing to its chemical stability, suitable band alignment, low toxicity, and excellent transparency. However, the photovoltaic performance and long-term stability of TiO₂-based DSSCs are still limited by charge recombination, slow electron transport, interfacial losses, and structural degradation. This review summarizes recent advances in defect engineering, morphology engineering, and interface engineering of TiO₂ photoanodes for high-performance DSSCs. Attention is given to the role of oxygen vacancies, Ti³⁺ states, metal/non-metal doping, and heterostructure formation in tailoring the electronic structure and charge transport behavior of TiO₂. The influence of various TiO₂ nanostructures, including nanoparticles, nanotubes, nanorods, nanosheets, and hierarchical architectures, on dye adsorption, light scattering, electron mobility, and recombination dynamics is critically discussed. Furthermore, recent progress in interface engineering strategies such as passivation layers, blocking layers, MXene incorporation, composite photoanodes, and atomic layer deposition are examined in relation to interfacial charge transfer and device stability. Current challenges involving defect-induced recombination, morphology-related transport trade-offs, and long-term degradation are also analyzed. Finally, future perspectives on hierarchical nanoarchitectures, multifunctional interfaces, flexible DSSCs, and hybrid TiO₂ systems are presented. This review provides an integrated understanding of how defect, morphology, and interface engineering collectively govern the performance of TiO₂ photoanodes and offers design guidelines for next-generation high-efficiency and stable DSSCs. Full article

Photocatalytic CO₂ reduction into CH₄ is a promising route for solar fuel production, but its efficiency is still limited by poor charge separation, insufficient CO₂ activation, and sluggish multi-electron transfer kinetics. Herein, Cu-modified TiO₂ (Cu/TiO₂) was prepared by calcining a Cu-modified defective MIL-125(Ti) precursor, denoted as Cu-MIL-125, through a temperature-controlled calcination strategy. The effects of calcination temperature on the structural evolution, surface chemical states, interfacial charge transport, and CO₂ photoreduction performance were examined. These results indicated that the Cu/TiO₂ was successfully prepared, while the crystallinity, porous structure, and interfacial electronic properties of Cu/TiO₂ were strongly dependent on the calcination temperature. Among the obtained samples, the Cu/TiO₂ sample obtained by calcining Cu-MIL-125 at 450 °C (450 Cu/TiO₂) exhibited the highest CH₄ formation rate, reaching 15.90 μmol g⁻¹ h⁻¹, corresponding to an approximately 9.8-fold enhancement over TiO₂ calcined from defective MIL-125(Ti) at 450 °C, together with a high CH₄ selectivity of 93.05%. Control experiments and ¹³CO₂ isotope-labeling tests confirmed that the detected carbon-containing products were generated from CO₂ under photocatalytic conditions. In situ diffuse reflectance infrared Fourier transform spectroscopy measurements further revealed the formation of carbonate, bicarbonate and hydrogenated carbon-containing intermediates during the reaction. This work offers a practical route for constructing metal–organic framework-derived Cu/TiO₂ photocatalysts for selective CH₄ production from CO₂. Full article

Nanoparticles have attracted considerable interest for biomedical and catalytic applications due to their unique functional properties. This study aims to evaluate the structural, optical, photoelectric, photocatalytic, and wound-healing performance of cetyltrimethylammonium bromide (CTAB) and cellulose nanoparticles with complementary physicochemical characteristics. The nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Ultraviolet–Visible (UV–Vis) spectroscopy, while photoelectric properties were assessed through current–voltage (I–V) measurements. Photocatalytic activity was evaluated using methylene blue degradation under solar irradiation, and in vivo wound healing was examined using a rat excisional model over 13 days. Cellulose nanoparticles exhibited nearly double the photocurrent compared to CTAB, indicating enhanced charge transport efficiency. Photocatalytic results showed that cellulose achieved approximately ~70% degradation within 210 s, compared to ~50% for CTAB. In vivo findings revealed that cellulose achieved 82% wound closure, compared with 71% for CTAB, 67% for Betadine, and 35% for untreated controls, accompanied by improved tissue regeneration. Overall, cellulose nanoparticles exhibited better photoelectrochemical, photocatalytic, and wound-healing properties, whereas CTAB provided structural integrity and antimicrobial properties. These materials are therefore promising multifunctional nanomaterials for catalytic and biological applications. Full article