Search Results (1,257)

The increasing concentration of atmospheric CO₂ has intensified the urgent need for efficient and sustainable carbon capture technologies. Covalent organic frameworks (COFs) have emerged as a highly promising class of porous crystalline materials for CO₂ adsorption and separation owing to their structural tunability, high surface area, and precisely designable pore environments. This review summarizes recent advances in COF-based CO₂ capture systems, covering pristine COFs, functionalized frameworks, composite materials, and membrane-based architectures. In pristine COFs, CO₂ adsorption is mainly governed by micropore confinement and physisorption within well-defined channels, where surface area and pore size distribution play key roles. Functionalized COFs introduce additional active sites, including amine groups, heteroatoms, ionic functionalities, and alkali metal centers, which significantly enhance CO₂ affinity through stronger electrostatic and acid–base interactions, often leading to mixed physisorption–chemisorption behavior. Composite COFs and mixed-matrix membranes further improve performance through synergistic effects, interfacial engineering, and enhanced mass transport. Despite these advantages, challenges remain in achieving an optimal balance between capacity, selectivity, and regenerability under realistic conditions such as humidity, low CO₂ partial pressure, and multicomponent gas streams. Issues related to scalable synthesis, structural stability, and processability also limit practical applications. Overall, this review highlights key structure–property relationships and outlines future directions, including humid-stable COFs, direct air capture, computational design strategies, and advanced membrane technologies, for next-generation CO₂ capture materials. Full article

The development of sustainable electrocatalysts for clean energy by modifying biomass-derived activated carbon with nitrogen and transition metals is presented. Activated carbon (AWC) material was obtained using alder wood char as a precursor, while nitrogen and cobalt or copper nanoparticles were incorporated with the aim of creating efficient materials for hydrazine oxidation (HzOR) and direct hydrazine–hydrogen peroxide fuel cells (DHHPFC, N₂H₄–H₂O₂). The composition, structure, and surface morphology of the created materials were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The activity of the AWC, AWC–Co–N, and AWC–Cu–N catalysts for HzOR was investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). N₂H₄–H₂O₂ fuel-cell tests were performed by applying the catalysts as both the anode and cathode. It was found that all materials retained a hierarchical porous carbon framework, while metal incorporation altered surface compactness. Cobalt doping produced well-dispersed Co nanoparticles and abundant Co–N–C coordination sites, whereas Cu introduction resulted in moderately compact structures with uniformly distributed Cu-based nanoparticles. Electrochemical measurements demonstrated that both metal dopants enhanced HzOR activity, with the catalytic performance following the order of AWC–Co–N > AWC–Cu–N > AWC. Fuel-cell testing further confirmed this trend: AWC–Co–N achieved the highest maximum power density (30.4 mW cm⁻²), outperforming AWC–Cu–N (17.7 mW cm⁻²). These results identify AWC–Co–N as a highly effective bifunctional electrocatalyst for DHHPFCs. Full article

The development of highly efficient, stable, and cost-effective non-precious metal electrocatalysts to replace conventional platinum-based materials holds profound significance for accelerating the commercialization of advanced energy conversion devices, such as zinc–air batteries (ZABs). Herein, we propose a facile and highly efficient strategy to prepare a defect-rich, highly active nitrogen-doped porous carbon-based electrocatalyst (denoted U-Fe-N-C, urea-assisted iron–nitrogen–carbon material), via high-temperature co-pyrolysis of heme with urea. Our results demonstrate that urea not only serves as an excellent nitrogen source during pyrolysis, introducing abundant topological defects and heteroatom doping sites, but also induces the carbon substrate to form a hierarchical sponge-like porous structure with a high specific surface area. This unique microenvironment effectively prevents the agglomeration of iron species at high temperatures, achieving enhanced dispersion of iron species stabilized within the nitrogen-rich carbon matrix. Electrochemical evaluations reveal that under the optimal synthesis conditions (a precursor mass ratio of 1:3, calcination at 900 °C), U-Fe-N-C exhibits excellent oxygen reduction reaction (ORR) catalytic performance, delivering a half-wave potential of 0.731 V vs. RHE, and shows long-term operational durability that significantly surpasses that of commercial Pt/C. Furthermore, liquid rechargeable zinc–air batteries assembled with U-Fe-N-C as the air cathode deliver remarkable cycling stability, operating for up to 270 h of charge–discharge cycling without noticeable performance degradation. This study not only provides useful insights into the mechanisms of pore formation and assistance but also offers a practical perspective for the rational design and scalable synthesis of high-performance metal–nitrogen–carbon (M-N-C) electrocatalysts. Full article

The successful realization of a circular economy in the cement industry, coupled with a substantial reduction in carbon emissions, relies on the development of sustainable alternative binder systems. This study investigated the physicomechanical performance and sulfate resistance of composites produced by alkali activation of natural perlite and blast furnace slag. The aim of the research was to improve mechanical properties under low- and medium-alkalinity conditions (5–10 M NaOH). The samples were cured at an ambient temperature of 20 °C and then treated with heat at 60 °C. These samples were then mechanically processed and subjected to five soak–dry cycles in 5% and 10% Na₂SO₄ solutions. The results showed that heat treatment resulted in the formation of a dense C-A-S-H gel, increasing compressive strength approximately eightfold, from 11.64 MPa to 92 MPa. However, perlite’s porous and brittle structure limits its flexural strength to 0.27 MPa; this value is insufficient for structural applications. Under severe sulfate attack (10% Na₂SO₄), samples cured at ambient temperature showed a 12% mass increase in the first cycle due to solution infiltration into capillary voids. As a consequence of extensive ettringite and gypsum formation, the specimens experienced severe deterioration, resulting in a complete loss of mechanical integrity and a residual compressive strength of 0 MPa. In contrast, heat-treated samples showed limited ion diffusion due to a denser matrix and an improved aggregate interface transition zone, resulting in a 2.6% mass increase and a residual compressive strength of 5.17 MPa. Consequently, the obtained findings indicate that thermally treated alkali-activated slag–perlite composites exhibit high resistance against sodium sulfate attack and may have potential for use in specific industrial environments with high sulfate concentrations. However, the performance of these materials under more complex aggressive conditions, such as mining environments involving magnesium sulfate exposure and acidic drainage waters, should be further validated through future studies. Full article

To address the pronounced interlayer productivity disparity and uneven reserve utilization during the development of multilayer low-permeability porous carbonate gas reservoirs, the G gas field on the right bank of the Amu Darya River was selected as the study area. Core-parallel physical simulation experiments, orthogonal numerical simulations, and production logging test (PLT) data were integrated to investigate the mechanisms of interlayer interference and its key controlling factors under multilayer commingled production. The results show that interlayer interference is primarily controlled by the permeability contrast and production differential. With increasing permeability contrast, high-permeability layers contribute a larger proportion of total production, whereas the utilization of medium- and low-permeability layers declines, thereby intensifying interlayer interference. Under the same permeability configuration, the interference coefficient increases with increasing production differential. Moreover, compared with the two-layer commingled-production cases, the three-layer system showed a stronger response to pressure-differential variation. When the production differential increased from 1 MPa to 5 MPa, the interference coefficient in the three-layer system increased from 9.84% to 27.83%, indicating more pronounced productivity loss in the medium- and low-permeability layers. Orthogonal numerical simulation indicates that the sensitivity of the main controlling factors follows the order of production differential ≥ permeability ratio > thickness ratio > gas viscosity. PLT data further validate the reliability of the experimental and numerical simulation results. During the development of Well G-22, the XVac layer consistently dominated gas production, whereas the XVm and XVp layers acted as supplementary contributors, indicating a dynamic production pattern in which high-permeability layers are preferentially activated and medium- and low-permeability layers contribute progressively at later stages. These findings demonstrate that permeability heterogeneity is the fundamental cause of interlayer interference, while the production differential serves as an important amplifying factor. This study provides a theoretical basis for zonal production allocation, optimization of the production differential, and stable production management in multilayer low-permeability porous carbonate gas reservoirs. Full article

To address the urgent demand for eco-friendly and low-cost catalysts to replace toxic heavy-metal additives in energetic materials, this work focuses on developing biomass-derived copper-doped porous carbon (CuPC) as a high-efficiency catalyst for the thermal decomposition and combustion of molecular perovskite energetic material (H₂dabco)NH₄(ClO₄)₃(DAP-4). Biomass carbonaceous material has garnered extensive attention in many fields, owing to the low cost, high utilization efficiency, and environment protection. Herein, the CuPC catalysts were rationally designed and fabricated via the high-temperature carbonization treatment of biomass carbonaceous material precursor. The catalytic effects of CuPC on the thermal decomposition and combustion characteristics of DAP-4 were systematically investigated. The results revealed that CuPC possessed inherent catalysis property on the decomposition and combustion reaction of DAP-4. Cu_xO_y nanoparticles were uniformly distributed on the surface of carbonized biomass substrates, endowing the catalysts with superior dispersibility. Thermal analysis results indicated that the addition of 5 wt% CuPC-3 reduced the thermal decomposition peak temperature from 378 °C of raw DAP-4 to 350 °C of DAP-4/CuPC-3. Moreover, the apparent activation energy of DAP-4 was notably decreased with the incorporation of CuPC catalysts. The combustion characterization results demonstrated that DAP-4 exhibited a more intense combustion process with the addition of CuPC, accompanied by elevated maximum combustion temperature and enhanced combustion heat. The catalytic mechanism of CuPC on the thermal decomposition and combustion of DAP-4 was further proposed. This work provides a targeted strategy for designing sustainable biomass-based catalysts to optimize the energy release performance of advanced molecular perovskite energetic materials. Full article

This study investigates the potential of several sustainable agricultural by-products—including olive stones, cork, and almond shells, which are locally available in Alentejo, Portugal—as low-cost adsorbents for the removal of methylene blue (MB) from synthetic wastewater. The biomass residues were evaluated both in their raw form and after conversion into activated carbons (ACs) through chemical activation with KOH at 973 K. The produced ACs exhibited well-developed surface areas (760–1103.5 m² g⁻¹) and porous structures (0.31–0.51 cm³ g⁻¹). The adsorbents were characterised in terms of their chemical and textural properties. Raw biomass materials presented acidic surface groups, whereas the ACs presented neutral or basic groups. Batch adsorption experiments were conducted to assess the effects of adsorbent particle size, solution pH, initial MB concentration, stirring speed, contact time, and temperature on dye removal efficiency. Among all tested materials, the ACs achieved superior MB adsorption capacities, ranging from 244.2 to 317.6 mg g⁻¹, compared to the untreated biomass adsorbents, which showed capacities between 34.1 and 46.4 mg g⁻¹. The adsorption data were best described by the Langmuir isotherm model, while the kinetic data closely followed the pseudo-second-order (PSO) model. Thermodynamic analysis revealed that MB adsorption was spontaneous and endothermic; however, the relatively low enthalpy values indicated that physical interactions contributed significantly, particularly in the case of the raw biomass adsorbents. This suggests that the PSO model may also be applicable when physical adsorption is the dominant mechanism. This work demonstrates the novel use of cork, olive stone, and almond shell biomasses and their derived ACs as sustainable adsorbents, highlighting an integrated approach that simultaneously promotes efficient wastewater treatment, waste valorisation, and circular economy-driven socio-economic development. Full article

Despite its critical role in disease diagnosis as a radiopharmaceutical, Fluorine-18 generates medical wastewater that necessitates efficient treatment, for which membrane adsorption stands out as a potent method, albeit one that demands high-performance membranes with exceptional permeability and adsorption capacity. This study presents a novel cerium-loaded amyloid fibril hybrid membrane designed for efficient removal of fluorine-18 from such wastewater. The membrane is fabricated through a facile process involving oxidation–precipitation of cerium species onto amyloid fibrils, followed by vacuum filtration, with further compositional tuning via incorporation of porous silica or activated carbon dopants. The resulting membrane retains the characteristic amyloid fibril structure and exhibits high water permeability with a flux of up to 803.3 L/(m²·h·bar), superior to most of the other membrane materials. It effectively removes fluoride ions (F⁻) from both low and high-concentration solutions, achieving a removal efficiency of up to 99% and a maximum adsorption capacity of 580 mg/g, outperforming many existing membrane materials. The hybrid membrane also demonstrates notable resistance to ionic interference, enabling selective F⁻ adsorption from solutions containing high concentrations of Cl⁻, NO₃⁻ and SO₄²⁻, with a distribution coefficient (Kd) as high as 4.1 × 10⁴ mL/g; furthermore, it maintains a fluoride removal rate above 51% after ten consecutive adsorption cycles. The membrane retains 51% of its initial fluoride removal efficiency after 10 cycles, indicating potential for repeated use, although further optimization or regeneration strategies would be required to fully restore performance. Mechanistic investigations reveal that F⁻ adsorption occurs mainly through ion exchange with hydroxyl groups on CeO₂. This work introduces a promising novel material with significant potential for the efficient treatment of medical radioactive wastewater containing fluorine-18. Full article

This study presents a sodium alginate/chitosan/activated carbon (SA/CS/AC) gel microspheres loaded with Citrus reticulata peel allelochemicals for continuous inhibition of Microcystis aeruginosa by controlled release. Preparation parameters were optimized via response surface methodology (RSM) for improved algal inhibition, yielding an optimal formulation: 1.97% SA, 0.76% CS, 0.31% AC. The optimized gel microspheres showed a 7-day inhibition rate of 85.17 ± 2.49%, consistent with the predicted 85.29%. Characterization revealed that AC optimized the gel’s porous structure and surface functionality, providing more adsorption sites for allelochemicals. This helps improve the loading capacity of the gel microspheres and enables stable sustained release, with a cumulative release of 70% over 25 days. Algal inhibition declined slightly from day 7 to 30 due to allelochemical depletion but remained 76.27%, versus 30.58% for the blank SA/CS/AC carrier and 52.81% for the allelochemical-loaded SA/CS gel microspheres. AC thus synergistically strengthens algal inhibition by elevating allelochemical loading and prolonging activity, providing a feasible strategy for sustainable cyanobacterial bloom control. Full article

Geopolymers, alkali-activated aluminosilicate materials, have gained increasing attention as sustainable adsorbents for wastewater treatment due to their low-temperature synthesis, cost-effectiveness, and ease of shaping into mechanically robust structures. Their intrinsic negatively charged framework promotes the adsorption of cationic species; however, pristine geopolymers typically exhibit moderate performance, with adsorption capacities generally below ~70 mg g⁻¹ for dyes such as methylene blue (MB) and in the range of 20–100 mg g⁻¹ for divalent metal ions. To overcome these limitations, different strategies have been developed to tailor their pore structure and surface chemistry. In particular, foaming approaches enable the production of highly porous materials with tunable pore architecture, improving mass transfer and accessibility of active sites. Moreover, functionalization with carbon-based materials (e.g., activated carbon, graphene derivatives, biochar) or zeolitic phases significantly enhances adsorption performance, with reported capacities exceeding 500 mg g⁻¹ for Pb²⁺ and up to 450 mg g⁻¹ for organic dyes in optimized systems. This review provides a comprehensive overview of recent advances in geopolymer synthesis, pore engineering, and functionalization strategies, highlighting the relationships between composition, structure, and adsorption performance. Particular attention is devoted to the comparison between carbon-based and zeolitic modifications, as well as to the role of material shaping in enabling practical applications. Overall, the combination of tunable porosity, chemical versatility, and structural integrity positions functionalized geopolymers as promising candidates for the development of scalable and multifunctional adsorbents for wastewater remediation. Full article

Salt stress remains a major global stress factor among abiotic stresses limiting crop production. Salt stress is a major nutritional challenge, with poor agricultural production characterized by high soil sodium (Na⁺) levels in soil and plants. Soil salinity negatively affects plants through both osmotic effects and ionic toxicity. Hence, one of the main aims of agricultural scientists is to develop eco-friendly, sustainable solutions to alleviate soil salinity. Over the past decades, several studies have recommended biochar as a vital sustainable soil amendment to alleviate the negative consequences of soil salinity. Thus, this review builds on the literature on biochar-mediated alleviation of salt stress. Biochar is a carbon-rich material produced from biomass and feedstock via pyrolysis under little or no oxygen conditions. Due to its unique characteristics, such as high carbon, high surface area with porous and aromatic structure, high pH, high stability, cation exchange capacity, and water and nutrient retention capacity, it is considered an alternative for salt stress alleviation. Moreover, biochar facilitates sodium ion (Na⁺) adsorption, reduces Na⁺ uptake, and increases potassium ion (K⁺) uptake, enhancing nutrient cycling, helping plants maintain ionic balance and osmotic regulation. This, in turn, significantly increased the activity and diversity of soil microorganisms, enhanced their adhesion, and promoted their growth, thereby strengthening the plant’s salt resistance. Moreover, biochar-mediated improvements in microbial community dynamics and changes in the physical and biological properties of soil contribute to overall plant and soil health under salt stress. Hence, the present review aims to decipher the holistic patterns of biochar on soil and plant health, changes in physiological and defense mechanisms, plant hormones and signaling mechanisms, and the status of modified biochar under salt stress. Thus, the present review will pave the way for the production of salt-resilient crops with enhanced salinity tolerance. In conclusion, the use of biochar-based fertilizers and modified biochar enhanced microbial community dynamics in soil health homeostasis and soil fertility for agricultural production and food security. Full article

Conventional strategies for synthesizing porous structures generally depend on template-based methods, which involve not only excessive consumption of templating agents but also the use of hazardous chemicals, such as hydrofluoric acid or strong alkalis. Therefore, designing an effective and convenient strategy to fabricate porous SnO₂ is of significant practical relevance. Herein, we developed a top-down strategy to fabricate SnO₂ electrode via a thermal oxidation gas-release route, resulting in a bulk 3D hierarchical architecture with interconnected porous channels. Employing a bottom-up strategy, the gel precursors of these porous SnO₂ materials were synthesized on a large scale via a simple, surfactant- and template-free route, in accordance with green chemistry principles. The results show that the porous SnO₂(300) electrode materials possess a high specific surface area and exhibit favorable electrochemical energy-storage performance, achieving a high specific capacitance of 267.31 F g⁻¹ at a current density of 1 A g⁻¹. Furthermore, based on the gel electrolyte of PVA/KOH, an asymmetric supercapacitor device assembled using porous SnO₂(300) materials as the positive electrode and activated carbon as the negative electrode (denoted as P-SnO₂//AC) achieves an energy density of 32.49 Wh kg⁻¹ at the power density of 718.97 W kg⁻¹. This work presents a simple, cost-effective, environmentally friendly and scalable approach to synthesize SnO₂ materials with an advanced structural design. Full article

Fundamental understanding of the biomass pyrolysis process on a molecular level provides important guidelines for designing advanced porous carbon materials. In this study, the effects of KOH and K₂CO₃ activators on the thermal decomposition of agarose were elucidated using TG-FTIR-GCMS coupling techniques. The results demonstrate that the presence of KOH/K₂CO₃ shifts the pyrolysis gaseous products from organic fragments to CO₂ and H₂O, thereby preserving more C-C bonds in the solid phase and facilitating the subsequent aromatization process. Furthermore, compared to using KOH as the sole activator, the K₂CO₃/KOH co-activation strategy suppresses the violent evolution of CO₂ within the 300–400 °C range, thereby alleviating the structural shock to the material skeleton and ensuring its integrity. Therefore, the HPC-KCO prepared via a synergistic KOH/K₂CO₃ co-activation and one-step carbonization process exhibits a high specific surface area of 1670 m² g⁻¹ and successfully retains its interconnected hierarchical porous framework. Benefiting from its well-developed porous structure, HPC-KCO exhibits an impressive specific capacitance of 370 F g⁻¹ when employed in zinc-ion capacitors. Furthermore, the assembled symmetric supercapacitor demonstrates robust stability over a wide temperature range from −60 to 100 °C, delivering a remarkable capacitance of 121 F g⁻¹ even at −60 °C. This work offers a new insight for synthesizing porous structures of biomass-derived carbon. Full article

Carbon materials are regarded as cost-effective adsorbents due to their ability to remove heavy metals and organic pollutants from contaminated water. In this study, a novel phenol–formaldehyde resin-derived carbon microsphere (HCM_2.5) was designed and synthesized via a hard-template method combined with KOH activation. The prepared HCM_2.5 exhibits high selectivity and removal efficiency toward heavy metal ions and delivers an ultrahigh specific surface area of 2165 m²/g. A Cr(VI) removal efficiency exceeding 99.6% could be achieved in 50 ppm acidic solution, with excellent performance at pH 2–5. X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption analysis, and scanning electron microscopy (SEM) were used to confirm its porous structure with a high specific surface area. The results of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) reveal that the efficient heavy metal removal performance of HCM_2.5 is mainly attributed to its high specific surface area, as well as coordination and redox reactions between oxygen-containing functional groups and heavy metal ions. Furthermore, benefiting from its outstanding specific surface area and well-developed pore structure, a physical–chemical synergistic adsorption mechanism was proposed and systematically elucidated. Full article

This study aims to develop a sustainable, low-cost, and high-performance supercapacitor electrode by valorizing waste date seeds (Phoenix dactylifera) into activated carbon and integrating it with a polymer-based hydrogel electrolyte. Waste date seeds were successfully converted into high-performance activated carbon through hydrothermal carbonization followed by sulfuric acid (H₂SO₄) chemical activation. The obtained date seed activated carbon (DSAC) was applied as an electrode material and incorporated into a hydrogel electrolyte for supercapacitor applications. Structural, thermal, and morphological analyses using SEM, FTIR, XRD, and TGA confirmed the formation of a predominantly microporous carbon framework enriched with oxygen-containing functional groups, indicating effective carbonization and activation. The porous structure and surface chemistry contributed to enhanced electrochemical behavior. The electrochemical behavior of the prepared DSAC electrode was investigated through cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) analyses. The material exhibited a highest specific capacitance of 179 F g⁻¹ at a scan rate of 5 mV s⁻¹ and 159 F g⁻¹ at a current density of 0.2 A g⁻¹, demonstrating reliable and stable capacitive characteristics suitable for biomass-derived carbon-based supercapacitor applications. The device also exhibited excellent cycling stability over 5500 cycles, confirming long-term durability. The results demonstrate a promising and environmentally friendly strategy for advanced energy storage systems. Furthermore, the sustainability and cost-effectiveness of the proposed approach are attributed to the utilization of abundant date seed biomass and the simplicity of the hydrothermal–chemical activation process. The enhanced electrochemical performance is primarily associated with the hierarchical porous structure of the activated carbon and the improved ion transport facilitated by the hydrogel electrolyte, which collectively contribute to stable capacitive behavior and long-term cycling durability. Full article