Search Results (1,956)

The increasing share of renewable energy, such as solar and wind energy, in the energy mix implies a demand for sustainable energy storage systems for the mitigation of the intermittency of these energy sources. One option, therefore, is stationary batteries based on abundant sodium, stored in hard carbon (HC) anodes. In this work, following the sustainable by design principle, HCs were synthesized from cotton-based textile waste using three different thermochemical routes: hydrothermal carbonization (HTC) followed by pyrolysis under nitrogen atmosphere (HC-250-N), HTC followed by pyrolysis under a water vapor stream (HC-250-W), and direct pyrolysis (HC-direct-N). The impact of the synthesis method on the physicochemical properties and electrochemical performance of the HCs was thoroughly investigated. X-ray diffraction, Raman spectroscopy, electron microscopy, and gas adsorption analyses revealed that the HTC pre-treatment significantly enhanced the carbon content, microporosity, and degree of structural graphitic order. HC-250-N exhibited the highest graphitic character and more uniform microstructure, while HC-250-W showed the largest specific surface area and broader micropore distribution. Electrochemical evaluation in sodium-ion half-cells indicated that HC-250-N delivered the most balanced performance, with a reversible capacity of 335 mAh g⁻¹ and good cycling stability. These findings confirm the potential of textile waste-derived HCs as promising and sustainable anode materials for sodium-ion batteries and highlight the importance of tailoring synthesis parameters—such as HTC treatment and pyrolysis conditions—to optimize their structural and electrochemical properties. Full article

A series of Mg-Al LDH-based photocatalysts were synthesized via a one-pot steam-assisted method, including pure Mg-Al LDH (MA), Zn-In ion-exchange-modified Mg-Al LDH (MAZ), BiOCl-loaded pristine Mg-Al LDH (MAB), and Zn-In-modified Mg-Al LDH co-loaded with TiO₂ and BiOCl (MA/Zn-In/TiO₂/BiOCl, MAZB). The one-pot synthesis facilitated the in situ intercalation and uniform loading of BiOCl/TiO₂/Zn-In, while Zn²⁺/In³⁺ modified the MA layers via ion exchange, leading to an expansion of the interlayer spacing. The innovation of this work is reflected in two aspects: first, all raw materials are added via a one-pot strategy to achieve in situ preparation of modified hydrotalcite; second, this synthetic route features simple post-treatment without complicated washing, pressure filtration, and other tedious operations. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and N₂ adsorption–desorption isotherms. The bismuth chloride oxide/TiO₂/LDHs exhibited a layered structure, with the active components uniformly distributed between the layers and on the MA surface. Under simulated sunlight irradiation, MAZB achieved 97.5% degradation of 20 mg/L MB within 120 min, with an apparent rate constant of 0.0297 min⁻¹, which is 7.2 times, 2.4 times, and 2.9 times that of MA, MAZ, and MAB, respectively. The degradation rate of MAZB still remained at 89.5% after five cycles, demonstrating excellent stability and reusability. Compared with traditional hydrothermal methods, this steam-assisted system features mild reaction conditions (180 °C, atmospheric pressure), sodium-free raw materials, no washing requirement, and zero waste discharge, showing prominent green advantages. Full article

The article presents the synthesis and characterization of double halide perovskites (DHPs) with the nominal composition Cs₂Ag_0.2Na_0.4In_0.6M_0.4Cl₆ (M = Si, Ti, Zr), including photoluminescence (PL), photoluminescence excitation (PLE) spectra measured over a range of temperatures and kinetics of luminescence. The materials were synthesized via a hydrothermal method. The phase purity and elemental composition of the synthesized perovskites were confirmed by X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and elemental analysis, which demonstrated that the samples showed a close match to the target stoichiometry. The PL spectra exhibit a systematic shift toward the lower-energy region with substitution from Si to Zr, correlating with the progressive increase in the ionic radii of the substituting cations. All samples display broad, asymmetric emission bands, characteristic of self-trapped excitonic (STE) states. Temperature-dependent PL measurements reveal a gradual decrease in emission intensity with increasing temperature for all samples. The maximum emission intensity is observed in the range of ~160–200 K, corresponding to optimal conditions for radiative recombination, whereas the lowest intensity is recorded at ~80–100 K, where thermal activation of radiative centers is minimal. An increase in temperature is accompanied by a red shift in the PL bands across all compositions. In the Ti-doped DHP, a pronounced blue shift at low temperatures is observed, which can be attributed to the involvement of Ti³⁺-related electronic states. An analysis of the activation energy of thermal luminescence quenching and the results of time-resolved spectroscopy revealed the activation of thermal processes in the titanium-containing sample and their rapid decay, whereas replacing titanium with silicon leads to more stable luminescence in the crystal under study. Thus, the enhanced luminescence characteristics of double halide perovskites doped with Ti, Si, and Zr highlight their potential for advanced photonic and optoelectronic applications. Full article

Currently, dual-functional composites that simultaneously provide structural support and energy storage capabilities have garnered significant attention. However, the challenge of balancing mechanical strength and energy storage performance remains a limiting factor for their application. Herein, a novel N-doped reduced graphene oxide/nano-sulfur@porous SiC (N-rGO/S@porous SiC) composite material was successfully prepared by in situ embedding N-rGO supported with nano-sulfur into a 3D-printed porous SiC scaffold via a hydrothermal synthesis approach. The hierarchical porous structure composed of SiC and N-rGO facilitates mass transport of the liquid electrolyte. Benefiting from the high strength of SiC, the novel material achieves a compressive strength of 93.5 MPa. Benefiting from the synergistic effect of the N-rGO/S composite and the high ionic conductivity of the liquid electrolyte, the electrode material delivers superior electrochemical energy storage performance, achieving a specific capacitance of 800.7 mF/cm² at a current density of 1 mA/cm², together with remarkable rate capability and good cycling stability. To our knowledge, this composite exhibits a high level of integrated properties. More importantly, the strategy of integrating porous, high-strength supports with high-performance electrode materials opens new avenues for the synthesis of structure-energy-storage dual-functional composites. Full article

The development of highly efficient and stable photoanodes is essential for advancing photoelectrochemical cathodic protection towards practical applications. Herein, a novel ternary sulfide heterojunction was engineered through the construction of a three-dimensional interlocked architecture of ZnIn₂S₄ on SnIn₄S₈ nanosheets via a sequential hydrothermal synthesis. This unique three-dimensional interlocked configuration creates an intimate interface and continuous charge transfer highways, effectively addressing the slow electron movement and poor interfacial contact that plague conventional photoelectrodes. Spectroscopic and electrochemical analyses verified the formation of a Type-II band alignment, which drives the directional migration of photogenerated electrons from ZnIn₂S₄ to SnIn₄S₈ under an intrinsic built-in electric field. Upon coupling with 304 stainless steel, the ZnIn₂S₄/SnIn₄S₃ heterojunction exhibited outstanding photoelectrochemical cathodic protection performance. It delivered impressive photocurrent densities of 15.22, 19.76, and 72.27 μA·cm⁻² in 3.5 wt% NaCl, 0.1 M Na₂S₂O₃, and 0.1 M Na₂S/NaOH electrolytes, respectively, along with a prominent 720 mV cathodic potential shift in the Na₂S/NaOH system. Most importantly, its good activity and stability in the scavenger-free 3.5 wt% NaCl solution and natural seawater highlight the strong practical potential of this 3D interlocked photoanode for sustainable marine metal corrosion control. Through a strategic multi-electrolyte assessment, the underlying protection mechanisms were decoupled, revealing that the synergy between the heterojunction-induced charge separation enabled by the three-dimensional interlocked structure and electrolyte-specific hole scavenging is key to the enhanced performance. Full article

The purpose of this study was to examine the utilization of 0–45 μm aluminum hydrate fraction (gibbsite) manufactured by Alum SA Tulcea, as a precursor in the hydrothermal synthesis process of nanosize boehmite from gibbsite suspensions. Furthermore, the use of the produced material as adsorbent of lanthanum (III) ions was investigated using aqueous solutions. Thermogravimetric analysis (TG), Fourier Transform InfraRed Spectroscopy (FT-IR), Wide-Angle X-Ray Scattering (WAXS), and atomic force microscopy (AFM) were used to demonstrate the preparation of the required material. Additionally, the material point of zero charge (pHpzc) and material specific surface (using BET approach) were evaluated. By conducting adsorption studies, the specific parameters for the lanthanum adsorption process were evaluated. The effects of pH, the ratio of adsorbent material to La(III) quantity from aqueous solution, contact time, and La(III) initial concentration were also assessed. Based on the obtained experimental data, it was proved that the maximum adsorption capacity of 97.7 mg/g was obtained for a solid:liquid ratio = 0.1 g:25 mL, pH between 3 and 6, temperature of 298 K, and contact time of 90 min. The studied adsorption process is most effectively described by the Sips model, suggesting an intricate interaction among the adsorbent material and La (III) ions. The prepared adsorbent exhibited a good desorption capacity (higher than 93%) when 20% HCl was used for desorption. Full article

Carbon dots (CDs), including carbon quantum dots (CQDs), are ultra-small carbon-based nanomaterials, typically below 10 nm, with tunable photoluminescence, high aqueous dispersibility, favorable biocompatibility, low toxicity, and abundant surface functional groups. These properties make CDs promising multifunctional platforms for nanomedicine, particularly in bioimaging, biosensing, targeted drug/gene delivery, photodynamic therapy (PDT), photothermal therapy (PTT), antimicrobial treatment, and theranostic applications. This review critically examines recent advances in CD fabrication, including top-down, bottom-up, green biomass-derived, microwave-assisted, hydrothermal, and emerging hybrid strategies, with emphasis on how precursor selection, heteroatom doping, surface passivation, and polymer/ligand functionalization regulate optical performance, biological interaction, and therapeutic efficiency. The review discusses structural classification, including CQDs, graphene quantum dots (GQDs), carbon nanodots, and carbonized polymer dots (CPDs), together with major characterization approaches such as ultraviolet–visible (UV–Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). Particular attention is given to red/near-infrared (NIR) emission, renal clearance, drug-loading behavior, reactive oxygen species (ROS) generation, toxicity mechanisms, biodistribution, and long-term biosafety. This review also highlights key translational barriers, including batch-to-batch variability, limited standardization, scalable manufacturing, regulatory uncertainty, and incomplete pharmacokinetic evaluation. It considers artificial intelligence (AI) and machine learning (ML) as emerging tools for reproducible CD design. CDs represent versatile and clinically promising nanoplatforms, but their translation requires standardized synthesis, rigorous safety assessment, and application-specific regulatory validation. Full article

Sustainable management of industrial solid waste is critical for a circular economy. This study presents a novel approach for valorizing blast furnace slag (BFS) into NaA zeolite through selective acetic acid leaching followed by hydrothermal crystallization. The leaching step selectively extracts Ca²⁺ and Mg²⁺ while efficiently retaining silicon and aluminum in the solid residue, producing a reactive aluminosilicate precursor that facilitates zeolite nucleation and growth. The effects of the silicon-to-aluminum molar ratio (n(Si)/n(Al)), crystallization temperature, and duration on the phase evolution and morphology were systematically investigated. The results demonstrate that phase-pure NaA zeolite with high crystallinity and a uniform cubic morphology can be obtained from precursor gels with n(Si)/n(Al) ratios of 0.5–1.25. Optimal synthesis conditions were identified as n(Na):n(Si):n(Al):n(H₂O) = 6:1:1:240 at 373 K for 8 h. The resulting zeolites exhibit a BET specific surface area of 52.1 m²/g, a micropore volume of 0.016 cm³/g, an average adsorption pore size of 4.7 nm, and an external specific surface area of 12.8 m²/g. It achieved near-complete removal of Cu²⁺ and high adsorption efficiencies for Pb²⁺ (77.78%) and Ni²⁺ (71.79%) from 250 mg/L solutions at 298 K with a dosage of 4.0 g/L, following the affinity sequence Cu²⁺ > Pb²⁺ > Ni²⁺, with all pairwise differences statistically significant at p < 0.001, using one-way ANOVA and Tukey’s HSD tests. The adsorption of three metal ions was most accurately described by the Freundlich isotherm and pseudo-second-order kinetic models, indicating heterogeneous multilayer chemisorption. The theoretical maximum monolayer adsorption capacities (q_max) were 307.67 mg/g for Cu²⁺, 246.09 mg/g for Pb²⁺, and 173.79 mg/g for Ni²⁺, whereas the kinetic equilibrium adsorption capacities (q_e) reached 62.69, 48.85 and 41.69 mg/g, respectively. This study demonstrates a value-added strategy for valorizing BFS into a micro-mesoporous adsorbent, advancing both circular resource utilization and environmental remediation. Full article

Rare-earth hydroxycarbonates and oxycarbonates are attractive functional materials because their crystal chemistry and optical response can be tailored through controlled cation substitution. In this work, Eu-doped lanthanum hydroxycarbonates with nominal europium contents of 1, 3, and 5 mol% were synthesized by combining co-precipitation and hydrothermal treatment at 140 °C for 24 h and subsequently calcined at 500 °C for 0.5 h to obtain the corresponding oxycarbonates. X-ray diffraction showed that the as-synthesized powders consist of single-phase hexagonal LaCO₃OH, while the calcined products are single-phase La₂O₂CO₃. In both structural families, systematic peak shifts with increasing Eu content indicated the formation of homogeneous substitutional solid solutions. Thermal analysis revealed a clear two-step decomposition pathway for the hydroxycarbonate precursors, with endothermic events at about 530 and 850 °C, consistent with the sequential transformation from hydroxycarbonate to oxycarbonate and, finally, to oxide. UV-Vis absorption measurements highlighted a dopant-dependent shift in the absorption edge in both hydroxycarbonate and oxycarbonate systems. Kubelka–Munk analysis showed that the estimated band-gap energy increases with Eu content, from 4.9 to 5.4 eV for LaCO₃OH-based samples and from 4.7 to 5.1 eV for La₂O₂CO₃-based samples. These results demonstrate that europium incorporation is an effective strategy for tuning the structural evolution and optical properties of lanthanum carbonate-derived materials, thus supporting their potential use in UV-responsive rare-earth-based functional systems. Full article

Radon (²²²Rn) and thoron (²²⁰Rn) are widely used to investigate diffuse degassing, fault-zone permeability, hydrothermal circulation, and subsurface unrest, but their signals are not direct proxies for a single process. This manuscript is a critical synthesis and methodological article that develops a reduced inference framework for interpreting radon–thoron observations in volcanic, tectonic, and hydrothermal settings. The framework separates accessible support of the immediate radium parents ²²⁶Ra and ²²⁴Ra, recoil-scale release into the mobile phase, multiphase transport, geological carrier-gas throughput, and observational closure. It also distinguishes total activity flux from activity concentration and chamber throughput from natural carrier-gas dilution. Synthetic illustrative experiments test the internal behavior of the reduced operator; a concise re-reading of the public Upper Rhine Graben dataset illustrates the limits of concentration-only inference; and published volcanic and hydrothermal examples are used as literature-grounded vignettes. The purpose is not to validate a universal inversion model but to define what can be inferred from different observation packages. The paper, therefore, emphasizes three operational levels: anomaly reporting, mechanism discrimination, and local inversion. Full article

This study investigates the hydrothermal modification of commercial titanium dioxide (TiO₂) in the presence of a natural licorice root extract (Glycyrrhiza glabra L.), serving as a stabilizing and growth-modulating agent. The experimental framework combines hydrothermal treatment in a Teflon-lined autoclave with subsequent thermal calcination to elucidate the structural, morphological, and chemical evolution of the material. The plant-based extract significantly influences particle assembly during synthesis, fostering the formation of an initial organic–inorganic hybrid system that results in enhanced morphological homogeneity compared to pristine TiO₂. Thermal analyses (TGA and DSC) demonstrated the progressive decomposition of the organic components with increasing temperature, yielding a thermally stable, predominantly inorganic material at 600 °C. Scanning Electron Microscopy (SEM) observations confirmed a more uniform particle distribution in the modified samples. X-ray diffraction (XRD) patterns corroborated that the primary crystalline phase of TiO₂ remains intact across all conditions, with structural variations limited to peak definition and long-range organization. Furthermore, FTIR spectroscopy supported the preservation of characteristic TiO₂ vibrational features while indicating a gradual depletion of weakly bound surface species following thermal treatment. In conclusion, these findings demonstrate that natural extracts can effectively function as growth-modulating agents, steering material organization without altering its intrinsic chemical properties. This approach aligns with the principles of Green Chemistry and the circular economy, highlighting the potential of renewable plant-based resources as functional additives for the sustainable processing of inorganic materials. Rather than seeking to outperform commercial benchmarks, this work establishes a viable and low-environmental-impact strategy for morphological and structural modulation. Full article

Despite exhibiting exceptional structural stability, spinel lithium titanate (Li₄Ti₅O₁₂, LTO) suffers from inherent limitations in both electronic conductivity and ionic diffusion kinetics, limiting its high-rate application. In this study, pringle-shaped Li₄Ti₅O₁₂/carbon (LTO/C) composite was synthesized using low-cost sucrose as the organic carbon source, using a facile hydrothermal-calcination method. Each pringle-shaped nanosheet was composed of Li₄Ti₅O₁₂ nanoparticles that are 15 nm in size, which can shorten lithium-ion diffusion distances as well as better the contact between electrolyte and active materials. Meanwhile, the uniform carbon cladding improves the material’s electronic conductivity. Owing to the synergistic effects between the mesoporous LTO nanosheets and carbon coating, LTO/C-6.31 wt% presented remarkable rate capability and cycling stability, delivering 145.5 mAh g⁻¹ at 20 C over 1000 cycles with 93.93% capacity retention. This work demonstrates an effective synthesis route to developing high-rate capability and long-cycle-life anode materials for LIBs. Full article

The rational design of electrode architectures is essential for advancing high-performance supercapacitors. In this study, Nd₂O₃ electrodes with controlled structural features were developed via a polyacrylic acid (PAA)-assisted hydrothermal approach. By systematically tuning PAA concentration, the growth mechanism of Nd₂O₃ was effectively regulated, leading to a distinct morphological transition from compact agglomerates to well-defined hierarchical structures. The optimized Nd₂O₃-P2 electrode exhibits a porous and interconnected architecture, providing enhanced electrolyte accessibility and shortened ion diffusion pathways. This structural optimization significantly improves electrochemical performance, delivering a high areal capacitance of 26.889 F/cm² at 10 mA/cm², along with excellent rate capability and reduced internal resistance. Kinetic analysis reveals that charge storage is predominantly governed by diffusion-controlled Faradaic processes, with the optimized structure facilitating rapid ion transport and efficient redox activity. Additionally, the electrode demonstrates excellent cycling durability, retaining 87.08% capacitance over 12,000 cycles. An asymmetric supercapacitor assembled using Nd₂O₃-P2 and activated carbon achieves stable operation up to 1.5 V, delivering good capacitance retention (81.2%) after 7000 cycles. This work highlights the effectiveness of PAA-induced structural tuning and provides a practical strategy for developing advanced rare earth oxide-based electrodes for energy storage applications. Full article

Reaction-bonded SiC (RBSC) ceramics exhibit limited hydrothermal corrosion resistance due to the presence of residual silicon. This study presents a strategy to enhance the corrosion resistance of RBSC through homogeneous incorporation of MoSi₂ and concurrent reduction in residual silicon content. Three material systems were fabricated via reactive melt infiltration: conventional RBSC with a SiC/C preform (SC), a SiC–MoSi₂ composite incorporating commercial Mo₂C powder via physical mixing (MC), and a SiC–MoSi₂ composite derived from a Mo₂C/C precursor synthesized by a molten salt method (MS). The Mo₂C/C composite synthesized at 1150 °C exhibited fine, uniformly distributed Mo₂C particles coated on carbon black, contrasting with the agglomerated distribution in commercial Mo₂C mixtures. During reactive sintering at 1600 °C, Mo₂C reacted with molten Si to form MoSi₂, reducing residual Si content. Sample MS achieved the lowest residual Si (8.77 ± 0.45 vol.%), followed by MC (12.43 ± 0.86 vol.%) and SC (19.17 ± 1.01 vol.%). All samples achieved near-full densification (open porosity < 0.1%), with bulk densities of 2.96 ± 0.05, 3.03 ± 0.03, and 3.07 ± 0.03 g/cm³ for SC, MC, and MS, respectively. Microstructurally, MS displayed homogeneous MoSi₂ dispersion, while MC showed partial MoSi₂ aggregation, and SC contained continuous residual Si regions. Hydrothermal corrosion tests at 345 °C and 15 MPa for 9 days demonstrated that corrosion resistance followed the order MS > MC > SC. After 9 days, weight loss was 22.3970 ± 1.2059 mg/cm² (SC), 17.6370 ± 0.8266 mg/cm² (MC), and 15.4347 ± 0.7807 mg/cm² (MS), with corrosion depths of 393.17 ± 27.46, 267.40 ± 24.44, and 224.60 ± 25.13 μm, respectively. The enhanced performance of MS arises from two synergistic factors: reduced residual Si minimizes large corrosion pores, while uniform distribution of MoSi₂ facilitates the formation of a stable, dissolution-resistant composite oxide layer composed of MoO₃ and SiO₂, in which MoO₃ restrains excessive dissolution of SiO₂ through a pinning effect. These findings demonstrate that combining residual Si reduction with homogeneous MoSi₂ incorporation via molten salt-synthesized precursors offers an effective strategy for improving hydrothermal corrosion resistance of reaction-bonded SiC-based materials for applications in high-temperature and high-pressure aqueous environments such as nuclear water reactors. Full article

While the petroleum industry undergoes structural adjustments in supply and demand alongside a green and low-carbon transition, water drilling mud generated during oil extraction poses severe environmental challenges. Consequently, addressing the solid waste pollution and disposal issues associated with drilling mud has become critical. In this study, ZSM-5 zeolite was synthesized using water drilling mud as a silicon and aluminum source, inexpensive n-butylamine as a template agent, and a combined approach of alkali-melting activation pre-treatment and seed-directed hydrothermal synthesis. By adjusting key parameters such as water content, template agent dosage, and seed addition, optimal synthesis conditions were determined. Based on these conditions, a series of ZSM-5 zeolites with varying silicon-to-aluminum ratios were synthesized. Characterization results from XRD, TEM, SEM, and N₂ adsorption–desorption experiments revealed that all prepared samples exhibited high crystallinity, regular morphology, and high specific surface area. ²⁷Al MAS NMR results indicated that almost aluminum species were located at the framework structures with four-coordination. In the 1,3,5-triisopropylbenzene cracking reaction, the conversion rate increased with decreasing silicon-to-aluminum ratio, consistent with variations in acid amount. These findings achieve high-value utilization of waste drilling mud, offering a novel pathway for low-cost synthesis of high-performance ZSM-5 zeolite. This breakthrough injects fresh momentum into the petroleum refining industry’s green sustainable development, fostering a win–win scenario that harmonizes ecological conservation with industrial profitability. Full article