Search Results (1,032)

Biowaste-derived porous carbon materials show promise as electrode materials for supercapacitors owing to their low cost, renewable nature, widespread availability, and high specific surface area. Herein, boron and nitrogen co-doped porous carbon was synthesized via a facile one-step activation approach using reed spike as carbon precursor, ammonium borate as both the nitrogen and boron source, and potassium bicarbonate as activator. The prepared PC-700 materials possess large specific surface areas with hierarchical porous architectures and rich N (2.54 at%), O (11.23 at%) and B (2.59 at%) functional groups. As an electrode material, the PC-700 materials show a specific capacitance of 329.6 F g⁻¹ at 0.5 A g⁻¹ and long lifespan. Notably, the assembled PC-700 symmetric super capacitor achieves an energy density of 20.5 Wh kg⁻¹ and excellent electrochemical stabilization (98.60% capacity retention after 10,000 cycles). Full article

Additive manufacturing provides a fabrication route for electrode components with controlled macrostructure; however, printable carbon inks that also incorporate oxygen reduction reaction active precursors remain underdeveloped. Here, XC-72 carbon was combined with selected metal precursors to prepare N–C, Fe–N–C, and Pt-containing carbon ink formulations for direct ink writing. The precursor mixtures were incorporated into a polyurethane-based matrix, pyrolyzed at 900 °C, and characterized using X-ray diffraction, oscillatory rheology, rotating ring-disk electrode measurements, Brunauer–Emmett–Teller surface-area analysis, and scanning electron microscopy. XRD confirmed retention of carbon diffraction features and the formation of metal-containing crystalline phases after pyrolysis. Oscillatory rheology showed storage moduli exceeding loss moduli for the tested formulations, indicating elastic-dominant behavior suitable for shape retention during printing. For the PGM-free formulations, incorporation of nitrogen and iron precursors improved ORR onset potential, half-wave potential, limiting current density, and electron-transfer selectivity relative to the carbon control. BET analysis showed a decrease in accessible surface area after precursor incorporation, consistent with partial pore blocking or structural modification during pyrolysis. These results establish a printable formulation platform for ORR-active carbon-based inks, while future work is required to isolate the effects of printed architecture, pore hierarchy, and durability under fuel-cell operating conditions. Full article

Carbon nanocages provide confined reaction environments for CO₂ reduction reaction (CO₂RR), but carbon sources must first cross their microporous graphitic shells to reach encapsulated catalytic sites. Here, molecular dynamics simulations were used to elucidate carbon-source transport through through-layer pores (TLPs), representing the edge-rich vertical micropores formed across stacked graphene layers in carbon nanocages. We examined the effects of pore diameter, N-doping, and pore depth on the transport of CO₂RR-relevant carbon species. Among the investigated structures, a 12.1 Å N-doped TLP achieved the highest area-normalized cross-pore transport ratio of 1.296 × 10⁻² Å⁻². N-doping preferentially enhanced neutral CO₂ transport, while producing only limited improvements for bicarbonate and carbonate ions. This selectivity originates from strong CO₂ interactions with N-containing pore-edge sites, which establish a CO₂-enriched interfacial region and promote adsorption-assisted capture–transfer without persistent molecular trapping. N-doping reduces both resistance contributions, leading to an approximately 30.4% decrease in pore-mouth resistance and ~45% reduction in pore-interior resistance at pore depths of 17.0 Å. These results identify short, appropriately sized, and N-functionalized through-layer micropores as favorable architectures for delivering CO₂ to confined catalysts, providing molecular design principles for carbon-nanocage nanoreactors for CO₂RR. Full article

Nitrites and nitrates are admitted into the body through the consumption of various foods, primarily cured meat products. These nitrites and nitrates are precursors of reactive nitrogen species NO and NO₂, which, in excess, promote nitrosative stress. Attempts have been made to combat oxidative and nitrosative stress through C₆₀ fullerenols in animal models. Furthermore, experimental and theoretical studies have shown that the use of carbon nanomaterials such as defective or doped graphene and C₆₀ metallofullerenes facilitates the capture of NO_x pollutants contained in the air. This leads us to propose that the inclusion of metals in C₆₀ fullerenols may have the potential to capture these reactive nitrogen species and be considered in nitrosative stress tests in animal models. Alternatively, viewed from another perspective, a certain grade of hydroxylation of metallofullerenes could enhance the capture of atmospheric nitrogen pollutants. Therefore, Li, Ca and Y metals were included in C₆₀ fullerenols at different coating grades. Using density functional theory (DFT), we analyzed the antiradical character of these metallofullerenols, and the adsorption energies of the free radicals (NO_x) were calculated to evaluate the ability of these metallofullerenols to adsorb these nitrogen species. Although both fullerenols and endohedral metallofullerenes have individually shown promise as radical scavengers, a systematic understanding of how the encapsulated metal and the grade of hydroxylation jointly govern the capture of nitrogen species is still lacking. In particular, it remains unclear whether increasing the number of hydroxyl groups monotonically enhances the capture capacity or whether optimal combinations of metal identity and surface functionalization exist. Addressing this gap is crucial, since excessive hydroxylation may alter the electronic structure, stability, and mechanism of interaction with NO_x radicals, potentially compromising capture capacity. Therefore, a rational evaluation that simultaneously considers electronic donor–acceptor properties, local reactivity, and adsorption thermodynamics is required to identify metallofullerenols with possible potential to sense or scavenge NO_x. Full article

A nitrogen-doped carbon-confined cobalt–iron bimetallic catalyst (CFNC) was fabricated through high-temperature pyrolysis of a ZIF-67-modified CoFe₂O₄ precursor and employed as a heterogeneous activator for peroxymonosulfate (PMS)-mediated Rhodamine B (RhB) degradation. The physicochemical properties of the as-prepared catalyst were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis. These analyses demonstrated that Co–Fe bimetallic species were successfully embedded within the nitrogen-doped carbon framework, forming a confined carbon-supported catalytic structure. Under optimized conditions (CFNC dosage of 20 mg L⁻¹, PMS concentration of 150 mg L⁻¹, and initial pH of 7), the CFNC/PMS system achieved 99.45% RhB removal within 10 min. Moreover, the catalyst retained 78.91% degradation efficiency after five successive cycles, indicating its satisfactory reusability and structural stability. Mechanistic investigations based on radical scavenging experiments and electron paramagnetic resonance (EPR) analysis revealed that PMS activation over CFNC involved the coexistence of radical and non-radical oxidation pathways, in which singlet oxygen (¹O₂) played a predominant role. The defect-rich nitrogen-doped carbon matrix facilitated PMS adsorption and activation, promoting the selective formation of ¹O₂, while the confined Co–Fe bimetallic sites contributed to efficient electron transfer during the catalytic process. The synergistic coupling between the Co–Fe active centers and conductive carbon framework accounted for the enhanced catalytic performance, suppressed metal leaching, and long-term stability of CFNC. This work presents a promising approach for constructing robust bimetallic carbon-based catalysts and advances the application of PMS-driven advanced oxidation processes for wastewater remediation. Full article

The research on semiconductor electrocatalysts has developed into an active field of study in the past decade. By constructing heterojunctions, one may efficiently overcome the limitations of semiconductors’ broad band gaps and low conductivity. This work uses a single-step hydrothermal approach to load nitrogen-doped carbon quantum dots onto TiO₂ nanoparticles, resulting in an excellent N−CQDs/TiO₂ catalyst with an Ohmic contact effect for better NORR electrocatalytic performance under ambient circumstances. The ammonia production rate is 4242.24 μg·h⁻¹·mg⁻¹ at an applied potential of −0.90 V vs. RHE (in a 0.10 M K₂SO₄ electrolyte), and the Faradaic efficiency is 88.02%. When compared to the unmodified TiO₂ catalytic performance, the ammonia generation rate doubles, and the Faradaic efficiency increases by 42.90%. A detailed investigation of the microstructure, charge transfer, NO adsorption, and reaction pathways of N−CQDs/TiO₂ was performed using density functional theory (DFT) computations. According to the theoretical results, nitrogen doping creates an uneven charge distribution on carbon quantum dots, enhancing NO adsorption by N−CQDs. The Ohmic contact between N−CQDs and TiO₂ facilitates charge transfer. The ICOHP value is more negative during NO adsorption on N-doped carbon quantum dots, decreasing the N=O interaction and boosting the NORR, according to crystal orbital Hamilton population (COHP) research. We have established the excellent performance and catalytic mechanism of the N−CQDs/TiO₂ catalyst based on these discoveries, giving strong theoretical and experimental evidence for the creation of effective catalysts for nitrogen oxide reduction processes. Full article

The development of sustainable, smart food packaging materials that simultaneously provide antimicrobial protection and real-time monitoring of food quality is a critical frontier in food safety. This study reports the fabrication of a multifunctional amphiphilic emulgel designed for the detection of pathogen-induced metabolic pH changes in food systems. The system utilizes Pomegranate-derived nitrogen-doped quasi-spherical carbon dots (QS-CDs) as fluorescent nanoprobes and Rosemary Essential Oil (REO) as a natural antimicrobial agent, both encapsulated within a polyelectrolyte complex of chitosan and sugarcane bagasse-derived carboxymethyl cellulose (CMC). A low degree of substitution (DS = 0.4) was specifically engineered for the CMC to ensure an amphiphilic character, enabling nanocomposite complex stabilization of the REO droplets without synthetic surfactants. Structural characterization via Transmission Electron Microscopy (TEM) revealed well-dispersed QS-CDs (4.71–6.62 nm) and stable oil droplets (~605.49 nm) anchored within a zipped polymer network. Thermal analysis (TGA/DSC) using the Coats–Redfern model revealed a significant synergistic effect: the smart-emulgel exhibits a distinct two-stage degradation profile, with the high-temperature stage requiring an activation energy (E_a) of 95.19 kJ/mol, a substantial increase over the corresponding stage in the CD-emulgel baseline (18.69 kJ/mol). This enhanced stability is complemented by a slight increase in crystallinity (X_c from 0.11 to 0.14). While the smart-emulgel remains predominantly amorphous, this shift suggests that the integration of REO and QS-CDs into the polymer network promotes the formation of localized, more ordered domains, contributing to a more robust and structurally integrated matrix. The emulgel demonstrated a dual-mode optical response (colorimetric and fluorometric) sensitive to the metabolic byproducts (e.g., organic acids, amines, other alkaline compounds) produced by Escherichia coli and Staphylococcus aureus. These findings were corroborated by Density Functional Theory (DFT) calculations, which confirmed the thermodynamic stability and optimized electronic energy gaps for pH-responsive sensing. This research provides a green, high-performance platform for the real-time monitoring of food freshness and the prevention of foodborne illnesses. Full article

Dimethyl phthalate (DMP) is an environmental contaminant known for its endocrine-disrupting properties, and its removal poses a critical environmental challenge. In this paper, we present a theoretical study of the adsorption of the DMP molecule and its isomers on pristine and nitrogen-doped graphitic surfaces, which represent the pore walls of nanoporous activated carbon, using density functional theory (DFT) calculations. Detailed wavefunction analyses were performed to elucidate the nature of adsorption on the AC surfaces. Our results reveal that nitrogen doping improves phthalate adsorption in the following order: AC-Pristine < AC-NH₂ < AC-Graphitic-N < AC-Graphitic-2N. This enhancement arises from changes in charge distribution that introduce electrostatic interactions between the COOCH₃ groups of the molecules and nitrogen-doped atoms on the AC surface. This study provides mechanistic insights into DMP adsorption on nitrogen-doped AC and offers rational guidelines for designing efficient carbon-based adsorbents for the removal of phthalate esters from contaminated water and the environment. Full article

Catalytic ozonation is one of the advanced oxidation processes (AOPs) that have yielded promising results in the treatment of emerging pollutants, in which the catalyst plays a fundamental role. In this study, surface oxygen and nitrogen groups were introduced onto two commercial activated carbons, and their catalytic activity in the ozonation of lamotrigine, carbamazepine, and ibuprofen was evaluated. The modified activated carbons were characterized by N₂ adsorption at −196 °C, elemental analysis, thermogravimetric analysis (TGA) and determination of the pH at the point of zero charge (pH_pzc). The by-products formed in the catalytic ozonation of the compounds with each catalyst were identified, and the mineralization of the pollutants was determined. Finally, the catalysts that showed the best mineralization of the individual compounds were used for testing with the mixture of pharmaceutical contaminants. These catalysts reduced the total organic carbon (TOC) of the mixture by over 74% after 180 min of reaction. The mineralization of pollutants was improved by catalysts with higher nitrogen content and fewer surface oxygenated acid groups. Full article

Food industry wastewater containing synthetic dyes threatens ecological safety and human health. Therefore, efficient and environmentally friendly adsorbents that can remove synthetic food dyes from wastewater are urgently needed. In this work, a self-nitrogen-doped biochar (GSNBC), used for adsorption of food dyes including carmine and tartrazine, was facilely prepared by employing ginger straw waste as the carbon precursor and NaHCO₃ as a mild and relatively benign pore-forming agent via one-step pyrolysis. The as-prepared GSNBC featured well-developed porous structures, a specific surface area of 1712.52 m² g⁻¹, and rich oxygen- and nitrogen-containing functional surface groups. Particularly, GSNBC performed ultrafast adsorption, with approximately 90% of the equilibrium capacity within 1 min (600.13 mg g⁻¹ and 580.24 mg g⁻¹ for carmine and tartrazine, respectively), and reached adsorption equilibrium at about 10 min. In addition, it exhibited excellent regenerability. The adsorption kinetics and isotherms fit well with pseudo-second-order and Langmuir models. DFT calculations indicated that π–π stacking and hydrogen bonding were mainly responsible for the adsorption. This study presents not only a promising and efficient adsorbent for the remediation of dye-laden food industry wastewater but also a sustainable route for the resource utilization of ginger straw waste. Full article

Efficient removal of tetracycline (TC) from antibiotic-contaminated wastewater remains a significant challenge. In this study, a nitrogen-doped carbon modified cobalt ferrite (C@CoFe₂O₄, CF) composite was synthesized via a one-step hydrothermal method, and its adsorption–catalysis dual-function performance was systematically evaluated. Structural characterization revealed that CoFe₂O₄ nanoparticles were locally encapsulated by an N-doped carbonaceous layer, providing a high specific surface area and abundant nitrogen-containing active sites. Under optimized conditions, the CF-3/PMS system achieved 93.44% TC removal within 45 min, while CF-3 exhibited a maximum adsorption capacity of 486.5 mg·g⁻¹. Radical quenching experiments suggested that singlet oxygen (¹O₂) and superoxide radicals (O₂•⁻) played major roles in TC oxidation, while sulfate radicals (SO₄•⁻) and hydroxyl radicals (HO•) also contributed, indicating the coexistence of radical and non-radical oxidation pathways. TC adsorption was driven by surface complexation, π–π electron donor–acceptor interactions, and hydrogen bonding. The enhanced TC removal performance may arise from the cooperative contributions of N-containing carbon sites, accessible Co/Fe-containing regions, and interfacial electronic interactions, which promote TC enrichment and PMS-mediated oxidation. This work provides a promising strategy for designing bifunctional materials for antibiotic wastewater treatment. Full article

TiO₂–biochar-based photocatalysts are one of the materials exhibiting adsorption-photocatalytic synergy. They have been widely used in the remediation of water systems. Current reviews in this field predominantly focus on the following aspects. These include the preparation methods for composite materials, the pollutant removal performance, the adsorption–photocatalytic synergy, and environmental applications. However, there are still gaps in understanding the intrinsic relationships among photocatalyst morphology, surface functional groups, reactive oxygen species (ROS) generation, pollutant removal, and interfacial charge-transfer mechanisms. This restricts the potential for further enhancement of photocatalytic performance. To fill this gap, this review provides a comprehensive summary of the impact of various parameters on the morphology of TiO₂–biochar-based photocatalysts during in situ synthesis. These factors include titanium sources, carbon sources, preparation methods, solvents, pyrolysis conditions, and doping modifications. Further analysis is conducted to investigate the effects of morphological structure on the distribution characteristics of surface functional groups (e.g., oxygen- and nitrogen- containing groups), the generation of ROS, and the removal behavior of organic pollutants. Furthermore, this review focuses on the effects of three typical morphologies. The three typical morphologies include surface-adhered, pore-embedded, and interlayer-distributed. The role of morphology in charge transport behavior at interfaces is also examined. We systematically elucidate the mechanisms of coupled interactions among material morphology, surface functional groups, ROS, interfacial charge transport, and photocatalytic performance. An analytical framework is established to explore the relationships among morphology control, structural characteristics, and photocatalytic performance. Lastly, the limitations of TiO₂–biochar-based photocatalysts in environmental remediation processes are summarized. It also points the way forward for future development. Overall, this review provides a new theoretical perspective on the rational design and environmental applications of high-performance TiO₂–biochar-based photocatalysts. Full article

Silicon carbide (SiC) in its various structural modifications is widely used in power semiconductor electronics, operating under extreme conditions of high temperature, high voltage, and intense radiation. The discovery of spin defects (S > 0) with unique optical and coherent properties has further positioned SiC as a promising platform for quantum technologies. Here, we investigate a 6H-SiC single crystal co-doped with nitrogen and beryllium at concentrations of 10¹⁸ cm⁻³, using continuous-wave and pulsed electron paramagnetic resonance (EPR) and electron–nuclear double resonance (ENDOR). To enhance spectral resolution, experiments were conducted in the W-band (94 GHz; B = 3.4 T). Pulsed EPR identified nitrogen donors and beryllium acceptors in various lattice positions, allowing for the determination of their phase coherence and spin–lattice relaxation times. ENDOR measurements elucidated the electron–nuclear interactions with the local silicon and carbon environment, including distant coordination spheres. The observed hyperfine structures indicated highly delocalized spin density within the supercell. The TRIPLE resonance spectra verify coupled nuclear spin subspaces from different coordination spheres due to defect spin density. These results demonstrate the feasibility of incorporating dual impurities with distinct functional roles while preserving the crystal lattice’s structural features. Full article

The electrocatalytic reduction of CO₂ (CO₂RR) into value-added chemicals represents a promising strategy for achieving carbon-neutral energy conversion. However, it is fundamentally limited by sluggish reaction kinetics, insufficient product selectivity, and the competitive hydrogen evolution reaction (HER). Herein, density functional theory (DFT) calculations were employed to systematically investigate transition-metal single-atom catalysts anchored on boron and nitrogen co-doped graphene (TM@BNG), with the aim of elucidating the role of heteroatom-induced coordination engineering in modulating catalytic performance. The results demonstrate that B, N co-doping effectively tailors the electronic structure of the metal active sites, thereby optimizing the adsorption energetics of key intermediates and dictating the reaction pathways. Among the 27 candidates examined, Pd@BNG, Ag@BNG, Sc@BNG, Cu@BNG, Co@BNG, Cd@BNG, and Y@BNG exhibit superior catalytic activity and selectivity toward CO or HCOOH production, featuring low limiting potentials down to −0.06 V while simultaneously suppressing HER. Mechanistic analysis reveals that product selectivity is governed by the relative stabilization of *COOH and *HCOO intermediates during the initial proton-coupled electron transfer step. Furthermore, a physically interpretable descriptor (φ), derived from intrinsic electronic properties using machine-learning approaches, establishes a volcano-type correlation with the limiting potential and provides an effective activity-screening criterion within the investigated TM@BNG dataset. Collectively, these findings clarify the electronic-structure modulation of TM@BNG single-atom catalysts and provide a system-specific framework for screening related B/N-coordinated CO₂RR electrocatalysts. Full article

Capacitive deionization (CDI) is an environmentally advantageous desalination technology that is particularly suitable for the treatment of low- to medium-concentration saline water. Among different electrode materials, carbon materials are widely used due to their good electrical conductivity and high specific surface area, while they suffer from limited ion adsorption capacity. In this study, a cobalt/nitrogen-doped porous carbon fiber composite with Zn-induced porosity (CoNG@V@CNF), where “V” stands for “volatile pore-forming agent”, has been successfully prepared via electrospinning combined with a high-temperature carbonization process. The introduction of trace Co nanoparticles enhances the stability of porous graphene. In addition, N doping contributes to improved wettability and electronic conductivity, and the carbon fiber structure constructs a three-dimensional conductive network, providing fast channels for ion transport. Electrochemical tests show that the specific capacitance of CoNG@V@CNF reaches 252.76 F g⁻¹, demonstrating its superior charge storage capability. Furthermore, this study achieved a high salt adsorption capacity of 58.28 mg g⁻¹ and a competitive desalination rate performance of 1.94 mg g⁻¹ min⁻¹. After 40 cycles of testing, the salt adsorption capacity (SAC) remains at 56.72 mg g⁻¹, demonstrating its high stability during multiple charging and discharging processes. This work provides a new design strategy for developing high-performance CDI electrode materials. Full article