Lightweight, efficient, and reversible hydrogen storage materials are critical for the advancement of hydrogen-based energy technologies. In this work, we present a comprehensive density functional theory (DFT) investigation of hydrogen storage in pristine and metal-decorated C₈ carbon quantum dots (CQDs), representing ultrasmall, highly curved nanomaterials at the molecular–nanoscale interface. Lithium, magnesium, and titanium were investigated as representative decorating metals to tailor hydrogen adsorption strength and reversibility. The pristine C₈ quantum dot is structurally stable but exhibits negligible hydrogen affinity (−0.062 eV per H₂), rendering it unsuitable for practical storage applications. In contrast, metal decoration significantly enhances hydrogen adsorption while preserving molecular H₂ physisorption, yielding optimal single-molecule adsorption energies of −0.172, −0.304, and −0.451 eV for Li-, Mg-, and Ti-CQDs, respectively. Sequential adsorption analysis indicates exceptionally high hydrogen uptakes of up to 18 H₂ molecules for Li-CQD and 20 H₂ molecules for both Mg- and Ti-CQDs, corresponding to very high theoretical gravimetric capacities. Energy decomposition and interaction region analyses demonstrate that hydrogen uptake proceeds via a cooperative physisorption mechanism driven by dispersion, electrostatic, and polarization interactions, strongly enhanced by quantum confinement and extreme curvature effects inherent to the CQD. Grand canonical thermodynamic modeling confirms fully reversible hydrogen storage under practical temperature and pressure conditions. Among the systems studied, Mg-CQD exhibits the most favorable balance between adsorption strength and desorption accessibility, delivering a remarkable reversible gravimetric hydrogen storage capacity of 21.7 wt%, significantly surpassing most metal-decorated graphene-, fullerene-, and carbon nanotube-based materials reported to date. These results establish metal-decorated C₈ quantum dots as a new class of high-performance nanomaterials for reversible hydrogen storage and demonstrate the potential of ultrasmall carbon quantum dots to overcome the long-standing trade-off between hydrogen uptake and reversibility in nanostructured storage media.

The development of lightweight materials with high and reversible hydrogen storage capacity remains a key materials design challenge. Here, we investigate pristine and Ti-decorated C₃B₂ quantum dots using DFT, DLPNO-CCSD(T), and statistical thermodynamics. Pristine C₃B₂ strongly chemisorbs H₂ (E_ads = −0.93 eV), while Ti decoration moderates the interaction to a reversible regime (E_ads = −0.39 eV) through a balanced Kubas-type mechanism. Structural analysis shows that the Ti center becomes saturated at approximately five H₂ molecules via Kubas-type coordination, while additional hydrogen molecules are stabilized in the vicinity of the Ti–C₃B₂ framework through cooperative interactions. Sequential adsorption shows that up to 20 H₂ molecules can be stored per Ti–C₃B₂ unit. Thermodynamic and kinetic analyses reveal moderate desorption temperatures (≈322–366 K) and ultrafast release times, ensuring efficient cycling. Under realistic operating conditions (30/3 atm; 298/373 K), Ti–C₃B₂ achieves a reversible capacity of 20.10 wt%, surpassing DOE targets. These results highlight Ti-decorated C₃B₂ quantum dots as a promising, design-tunable platform for next-generation solid-state hydrogen storage.

In this study, cerium oxide (CeO₂) nanoparticles were successfully synthesized using a simple and cost-effective hydroxide-mediated precipitation method. Comprehensive characterization (XRD, SEM, TEM, FTIR, BET, and UV–Vis) confirmed the formation of uniformly distributed nanoparticles with an average size of ~100 nm, a well-defined crystalline structure, and a high specific surface area of 118.96 m²/g. The CeO₂ nanoparticles also exhibited a mesoporous framework with a pore volume of 0.39 cm³/g and an average pore radius of 2.27 nm, demonstrating favorable properties for adsorption applications. Adsorption experiments showed that CeO₂ nanoparticles effectively removed Pb²⁺ from aqueous solutions, achieving a maximum experimental adsorption capacity of 192 mg/g and a removal efficiency of 80% at pH 6 under the tested conditions. Kinetic analysis revealed that the pseudo-second-order model best described the adsorption process, suggesting chemisorption as the dominant mechanism, while equilibrium data were more accurately represented by the Langmuir isotherm model, which predicted a theoretical monolayer capacity (Qm) of 714.2 mg/g. Overall, the findings demonstrate that CeO₂ nanoparticles possess a strong affinity toward Pb²⁺ ions and exhibit promising adsorption performance, indicating their potential applicability for the treatment of lead-contaminated wastewater and their suitability for reuse following regeneration.

Metal-functionalized boron nitride nanostructures represent promising platforms for lightweight solid-state hydrogen storage. In this work, we perform a comprehensive density functional theory (DFT) investigation of pristine and metal-decorated B₄N₄ quantum dots (M = Li, Ti) to evaluate their structural stability, adsorption energetics, and near-ambient storage performance. Pristine B₄N₄ is highly stable but interacts weakly with H₂ (E_ads ≈ −0.12 eV), leading to negligible uptake under operating conditions. Li decoration moderately enhances adsorption through charge-induced polarization (E_ads ≈ −0.15 eV) but offers limited stabilization beyond the first few molecules. In contrast, Ti decoration fundamentally reshapes the interaction landscape, strengthening electrostatic, polarization, and dispersion contributions and enabling significantly stronger yet reversible H₂ binding (E_ads ≈ −0.36 eV). Sequential adsorption calculations predict maximum theoretical capacities of 14, 18, and 20 H₂ molecules for pristine, Li-, and Ti-decorated systems, respectively. Grand canonical thermodynamics show that Ti–B₄N₄ retains nearly its full loading at 30 bar and 298 K, while pristine and Li-decorated clusters store only negligible amounts. Under desorption conditions (3 bar, 373 K), Ti–B₄N₄ releases most of its stored hydrogen, yielding an exceptional reversible capacity of 15.1 wt%. Energy decomposition analysis attributes this performance to cooperative electrostatic, polarization, and dispersion enhancements. Ti–B₄N₄ emerges as a highly promising theoretical candidate, warranting future experimental validation.

Study presents a comparative analytical investigation into the green synthesis of monometallic and bimetallic nanoparticles using Punica granatum (pomegranate) extract, aimed at developing high-performance electrochemical sensors for the detection of ciprofloxacin (CIP) as a representative pharmaceutical pollutant. Three nanoparticle systems were successfully synthesized: monometallic Au@NPs and TiO₂@NPs, as well as the bimetallic AuTiO₂@NPs. Their structural and physicochemical characteristics were comprehensively analyzed using UV–Vis spectroscopy, FTIR, SEM, TEM, and XRD techniques. The obtained nanoparticles exhibited predominantly spherical morphologies with average particle sizes of approximately 40 ± 5 nm for Au@NPs, 50 ± 7 nm for TiO₂@NPs, and 60 ± 6 nm for AuTiO₂@NPs. These nanomaterials were subsequently employed to modify electrode surfaces for electrochemical sensing applications. Their analytical performance was evaluated using cyclic voltammetry (CV) and square-wave voltammetry (SWV). The sensors displayed excellent sensitivity, with limits of detection of 0.8 ppb for TiO₂@NPs, 0.8 ppb for Au@NPs, and 0.2 ppb for the AuTiO₂@NP-based sensor. The bimetallic platform demonstrated superior electrochemical behavior, enhanced signal intensity, and strong selectivity, achieving recovery rates of 98% in tap water and 103% in wastewater. Overall, the results confirm the effectiveness of green-synthesized bimetallic nanoparticles as efficient, low-cost materials for environmental monitoring of emerging pharmaceutical contaminants.

In this study, the phenolic content and biological activity of Salvia officinalis and Moringa oleifera leaves, were compared. Spectrophotometric methods are used to determine total phenolic content, total flavonoids, and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The methanolic extracts' antibacterial activity against three bacterial strains (Escherichia coli, Staphylococcus aureus, and Salmonella enterica) and Candida albicans as yeast was tested using the agar-well diffusion method. High Performance Liquid Chromatography with Diode Array Detector (HPLC-DAD) was performed to determine the specific phenolic compounds by comparing the retention times of phenolic compounds in samples to 19 standard compounds. Salvia officinalis and Moringa oleifera had total phenolic contents of 166.574 and 96.066 mg GAE/g, total flavonoids of 127.573 and 139.591 mg GAE/g, and DPPH radical scavenging activity of 70.445 and 61.392, respectively. Salvia officinalis exhibited the highest antimicrobial action against Candida albicans, while antibacterial activity was equal in the two samples. The HPLC results revealed variances in phenolic content. Salvia officinalis exhibited high composition levels. The main compounds discovered in the Salvia officinalis and Moringa oleifera samples were rosmarinic acid and gallic acid, respectively. All results are compared to previous studies.