Pub Date : 2026-01-24DOI: 10.1016/j.cartre.2026.100618
Péter Rózsa , Olga Krafcsik , Sándor Lenk , David Beke , Adam Gali
We functionalized fluorescent nanodiamonds of various sizes using a thiourea-based thiolation reaction to tailor their surface chemistry for biological and quantum technological applications. Spectroscopic analyses revealed that this reaction generates a complex mixture of sulfur- and nitrogen-containing groups, arising from the reaction of thiourea with surface functional groups and from oxidative cyclization. Since the charge stability of negatively charged nitrogen-vacancy (NV⁻) centers is strongly influenced by the near-surface electronic structure, surface modifications that enhance this stability—while preserving colloidal dispersibility and enabling further functionalization—are essential for quantum sensing applications. We show that the surface chemistry produced through the reaction of nanodiamonds with thiourea increases electron availability and favors the stabilization of the NV⁻ charge state. These results highlight the potential of thiourea-derived surface modification as an effective route to improve the quantum performance of nanodiamonds.
{"title":"Thiourea modification of fluorescent nanodiamonds towards enhanced quantum sensing","authors":"Péter Rózsa , Olga Krafcsik , Sándor Lenk , David Beke , Adam Gali","doi":"10.1016/j.cartre.2026.100618","DOIUrl":"10.1016/j.cartre.2026.100618","url":null,"abstract":"<div><div>We functionalized fluorescent nanodiamonds of various sizes using a thiourea-based thiolation reaction to tailor their surface chemistry for biological and quantum technological applications. Spectroscopic analyses revealed that this reaction generates a complex mixture of sulfur- and nitrogen-containing groups, arising from the reaction of thiourea with surface functional groups and from oxidative cyclization. Since the charge stability of negatively charged nitrogen-vacancy (NV⁻) centers is strongly influenced by the near-surface electronic structure, surface modifications that enhance this stability—while preserving colloidal dispersibility and enabling further functionalization—are essential for quantum sensing applications. We show that the surface chemistry produced through the reaction of nanodiamonds with thiourea increases electron availability and favors the stabilization of the NV⁻ charge state. These results highlight the potential of thiourea-derived surface modification as an effective route to improve the quantum performance of nanodiamonds.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"23 ","pages":"Article 100618"},"PeriodicalIF":3.9,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-24DOI: 10.1016/j.cartre.2026.100617
Christophe Coupeau , Arnaud Claudel , Michel Drouet , Ana Cristina Gomez Herrero , Vincent Bouchiat , Julien Durinck
Graphene monolayers were grown on copper crystals and then mechanically deformed using an original experimental equipment allowing to investigate in situ at the atomic scale by scanning tunnelling microscopy the evolution of coated specimens under increasing strains. The mechanical response of graphene monolayers under successive uniaxial mechanical compression is presented. In particular, the evolution of the as-grown buckles under strain is described and discussed within the framework of elastic modelling and the sliding of the graphene monolayer on its substrate is quantified.
{"title":"On the mechanical stability of graphene in situ grown on Cu(111) : Buckling and sliding","authors":"Christophe Coupeau , Arnaud Claudel , Michel Drouet , Ana Cristina Gomez Herrero , Vincent Bouchiat , Julien Durinck","doi":"10.1016/j.cartre.2026.100617","DOIUrl":"10.1016/j.cartre.2026.100617","url":null,"abstract":"<div><div>Graphene monolayers were grown on copper crystals and then mechanically deformed using an original experimental equipment allowing to investigate <em>in situ</em> at the atomic scale by scanning tunnelling microscopy the evolution of coated specimens under increasing strains. The mechanical response of graphene monolayers under successive uniaxial mechanical compression is presented. In particular, the evolution of the as-grown buckles under strain is described and discussed within the framework of elastic modelling and the sliding of the graphene monolayer on its substrate is quantified.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"23 ","pages":"Article 100617"},"PeriodicalIF":3.9,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polymer Electrolyte Membrane (PEM) fuel cells represent a promising green energy technology that efficiently converts hydrogen and oxygen (or air) into clean electricity. In this study, graphene nanosheets (GNS) were explored as an advanced material for the gas diffusion layer (GDL) due to their exceptional electrical conductivity, thermal dissipation, water management capability, and catalytic activity. A series of GNS–AC composites was prepared and characterised to optimise GDL performance. The AC (3:2 indicates the impregnation ratios between the PKS carbon powder weight and activated agent) composite exhibited an electrical conductivity of 4.46 × 10⁻⁴ S/cm and a surface area of 26.643 m²/g, while pure GNS achieved superior properties with 4.20 × 10¹ S/cm conductivity and 486.283 m²/g surface area. The optimised hybrid composite containing 90 % GNS and 10 % AC (3:2) demonstrated the highest power output of 0.0013 W under hydrogen and air flow rates of 0.5 L/min and 1 L/min, respectively (denoted as 05H1A). The continuous adsorption of GNS–AC from the higher porosity, electric conductivity determined the power of the fuel cell. These results confirm that the 90 %GNS + 10 %AC (3:2) composite is a highly effective GDL material for PEM fuel cells, offering enhanced performance with optimised gas flow conditions.
{"title":"Graphene nanosheets and palm-shell activated carbon in PEM fuel cell gas diffusion layers","authors":"Montri Luengchavanon , Sutida Marthosa , Ekasit Anancharoenwong , Shahariar Chowdhury","doi":"10.1016/j.cartre.2026.100616","DOIUrl":"10.1016/j.cartre.2026.100616","url":null,"abstract":"<div><div>Polymer Electrolyte Membrane (PEM) fuel cells represent a promising green energy technology that efficiently converts hydrogen and oxygen (or air) into clean electricity. In this study, graphene nanosheets (GNS) were explored as an advanced material for the gas diffusion layer (GDL) due to their exceptional electrical conductivity, thermal dissipation, water management capability, and catalytic activity. A series of GNS–AC composites was prepared and characterised to optimise GDL performance. The AC (3:2 indicates the impregnation ratios between the PKS carbon powder weight and activated agent) composite exhibited an electrical conductivity of 4.46 × 10⁻⁴ S/cm and a surface area of 26.643 m²/g, while pure GNS achieved superior properties with 4.20 × 10¹ S/cm conductivity and 486.283 m²/g surface area. The optimised hybrid composite containing 90 % GNS and 10 % AC (3:2) demonstrated the highest power output of 0.0013 W under hydrogen and air flow rates of 0.5 L/min and 1 L/min, respectively (denoted as 05H1A). The continuous adsorption of GNS–AC from the higher porosity, electric conductivity determined the power of the fuel cell. These results confirm that the 90 %GNS + 10 %AC (3:2) composite is a highly effective GDL material for PEM fuel cells, offering enhanced performance with optimised gas flow conditions.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"23 ","pages":"Article 100616"},"PeriodicalIF":3.9,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146079517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-14DOI: 10.1016/j.cartre.2026.100614
Sean Mallia, Matthew Anthony Xuereb, Ruben Gatt, Anthea Agius Anastasi, Daniel A. Vella
Graphene aerogels are being increasingly investigated, however, a robust understanding of the effects of synthesis parameters on their morphology and performance remains underdeveloped. This work reports on the successful microstructural control of reduced graphene oxide (rGO) aerogels, prepared via low-temperature hydrothermal reduction of GO, through changes to their gelation time and drying method. Using ascorbic acid as the reducing agent, the hydrogels were allowed to set at three gelation times; until the ‘just-gelled’ state or onset of gelling, for 80 minutes, and for 720 minutes, the latter typically reported in the literature. The hydrogels were then subjected to either freeze drying, or CO2 supercritical drying, followed by a final pyrolysis step. The resulting aerogels were characterised by scanning electron microscopy and micro-Raman spectroscopy. The mechanical properties of the rGO aerogels were assessed under compression loading, whereas their ability to perform in water was assessed by a simple immersion test. The results showed that freeze drying of the just-gelled hydrogels produced aerogels with large and cellular pores, low compressive moduli, and rather poor water stability. Longer gelation times produced denser aerogels with smaller pores and improved water stability. Such results suggest that for the freeze dried aerogels, the gelation time influences the microstructure of the rGO gel – short gelation times lead to weaker, more pliable hydrogels, less resistant to ice crystal growth upon freeze drying. Supercritical drying produced aerogels with randomly oriented nanometrically sized pores, high compressive moduli, and good water stability, irrespective of the gelation time.
{"title":"Altering the morphology of graphene aerogels through control of the gelation time and drying method","authors":"Sean Mallia, Matthew Anthony Xuereb, Ruben Gatt, Anthea Agius Anastasi, Daniel A. Vella","doi":"10.1016/j.cartre.2026.100614","DOIUrl":"10.1016/j.cartre.2026.100614","url":null,"abstract":"<div><div>Graphene aerogels are being increasingly investigated, however, a robust understanding of the effects of synthesis parameters on their morphology and performance remains underdeveloped. This work reports on the successful microstructural control of reduced graphene oxide (rGO) aerogels, prepared via low-temperature hydrothermal reduction of GO, through changes to their gelation time and drying method. Using ascorbic acid as the reducing agent, the hydrogels were allowed to set at three gelation times; until the ‘just-gelled’ state or onset of gelling, for 80 minutes, and for 720 minutes, the latter typically reported in the literature. The hydrogels were then subjected to either freeze drying, or CO<sub>2</sub> supercritical drying, followed by a final pyrolysis step. The resulting aerogels were characterised by scanning electron microscopy and micro-Raman spectroscopy. The mechanical properties of the rGO aerogels were assessed under compression loading, whereas their ability to perform in water was assessed by a simple immersion test. The results showed that freeze drying of the just-gelled hydrogels produced aerogels with large and cellular pores, low compressive moduli, and rather poor water stability. Longer gelation times produced denser aerogels with smaller pores and improved water stability. Such results suggest that for the freeze dried aerogels, the gelation time influences the microstructure of the rGO gel – short gelation times lead to weaker, more pliable hydrogels, less resistant to ice crystal growth upon freeze drying. Supercritical drying produced aerogels with randomly oriented nanometrically sized pores, high compressive moduli, and good water stability, irrespective of the gelation time.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"23 ","pages":"Article 100614"},"PeriodicalIF":3.9,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-14DOI: 10.1016/j.cartre.2026.100615
Hu Zong , Minhui Gao , Lei Yu , Su Zhao , Yunkui Liu , Yanyuan Zhou , Ying Zhou
Previous studies have shown that, at conventional power levels, ultrasonication can also produce graphene quantum dots (GQDs) via a top-down route, but it is more often used as an auxiliary step for dispersing or mildly exfoliating carbon materials, typically together with chemical oxidation or hydrothermal treatments rather than as the main synthesis method. Here, we use high-power ultrasonication and static pressure to strengthen cavitation, so that ultrasound itself becomes a direct and scalable strategy for GQD fabrication. In a pressurized circulation setup, we first track the evolution of graphite at 1500 W and observe a gradual transition from exfoliated sheets to fragmented pieces and finally nanoscale fragments (∼0.1 μm). At the same power, tuning the static pressure from 0 to 6 bar shows that the fraction of small fragments peaks around 2 bar, under which simple filtration and concentration are sufficient to obtain GQDs. Keeping this optimized pressure (2 bar) and increasing the power from 1500 to 3000 and 6000 W further boosts GQD production, accompanied by higher oxidation and larger dot size, as indicated by an increase in Raman ID/IG (0.33 → 0.46), expansion of lattice spacing (0.208 → 0.243 nm), and higher oxygen content in XPS. Consistently, the photoluminescence evolves into a pattern with coexisting excitation-independent and excitation-dependent regions, and the main emission at λex = 420 nm shifts slightly from ∼470 to ∼485 nm. Extending the same ultrasonic protocol to graphene oxide precursors yields GOQDs that show strong fluorescence under 365 nm UV without further concentration, suggesting a higher effective yield, while thermal reduction of GOQDs produces Re-GOQDs with larger sp² domains and GQD-like PL features, helping to clarify how ultrasonic power and precursor type jointly regulate the structure–optical response of GQDs/GOQDs.
{"title":"Effects of ultrasonic power on the fragmentation, oxidation, and photoluminescence of graphene quantum dots","authors":"Hu Zong , Minhui Gao , Lei Yu , Su Zhao , Yunkui Liu , Yanyuan Zhou , Ying Zhou","doi":"10.1016/j.cartre.2026.100615","DOIUrl":"10.1016/j.cartre.2026.100615","url":null,"abstract":"<div><div>Previous studies have shown that, at conventional power levels, ultrasonication can also produce graphene quantum dots (GQDs) via a top-down route, but it is more often used as an auxiliary step for dispersing or mildly exfoliating carbon materials, typically together with chemical oxidation or hydrothermal treatments rather than as the main synthesis method. Here, we use high-power ultrasonication and static pressure to strengthen cavitation, so that ultrasound itself becomes a direct and scalable strategy for GQD fabrication. In a pressurized circulation setup, we first track the evolution of graphite at 1500 W and observe a gradual transition from exfoliated sheets to fragmented pieces and finally nanoscale fragments (∼0.1 μm). At the same power, tuning the static pressure from 0 to 6 bar shows that the fraction of small fragments peaks around 2 bar, under which simple filtration and concentration are sufficient to obtain GQDs. Keeping this optimized pressure (2 bar) and increasing the power from 1500 to 3000 and 6000 W further boosts GQD production, accompanied by higher oxidation and larger dot size, as indicated by an increase in Raman I<sub>D</sub>/I<sub>G</sub> (0.33 → 0.46), expansion of lattice spacing (0.208 → 0.243 nm), and higher oxygen content in XPS. Consistently, the photoluminescence evolves into a pattern with coexisting excitation-independent and excitation-dependent regions, and the main emission at λ<sub>ex</sub> = 420 nm shifts slightly from ∼470 to ∼485 nm. Extending the same ultrasonic protocol to graphene oxide precursors yields GOQDs that show strong fluorescence under 365 nm UV without further concentration, suggesting a higher effective yield, while thermal reduction of GOQDs produces Re-GOQDs with larger sp² domains and GQD-like PL features, helping to clarify how ultrasonic power and precursor type jointly regulate the structure–optical response of GQDs/GOQDs.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"23 ","pages":"Article 100615"},"PeriodicalIF":3.9,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1016/j.cartre.2026.100613
Mozhgan Hadavand , Mehdi Mehrpooya , Mohammad Reza Ganjali
In response to the urgent need for high-performance non-precious metal electrocatalysts to address the energy crisis and reduce dependence on fossil fuels, we propose a novel approach to develop a highly selective and efficient electrocatalyst derived from metal-organic frameworks (MOFs). This electrocatalyst is designed for oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER). The innovative synthesized catalyst combines the synergistic effects of cobalt (Co), MXene, and lanthanide praseodymium (Pr), which are synthesized via a simple co-precipitation method. Cobalt plays an important role in enhancing electron transfer kinetics, and the layered structure of MXene significantly increases the active surface area, and the lanthanide praseodymium enhances electrical conductivity and structural and chemical stability. All of these help the synthesized catalyst to have a low overvoltage, thereby facilitating ORR, HER, and OER processes. The interaction between these components enhances the catalytic performance and benefits from unique morphological features, abundant heterogeneous interfaces, and excellent structural stability. The synthesized electrocatalysts were characterized using various techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmet-Teller (BET) analysis, along with electrochemical evaluations such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). Two separate samples of 10 %Pr-coreshell ZIF8@ZIF67/Mxene at 1:1 and 2:1 ratios showed exceptional electrocatalytic activity. For ORR, the samples showed impressive onset potentials of 0.904 V and 0.894 V (vs. RHE), while their HER onset potentials were recorded at -0.21 V and -0.20 V (vs. RHE). In terms of OER, the onset potentials were 1.62 V and 1.65 V, respectively. Notably, these materials showed outstanding stability and outperformed commercial Pt/C electrocatalysts, making them promising candidates for sustainable energy solutions.
{"title":"Efficient electrocatalysts derived from praseodymium-doped MOFs and MXene for oxygen reduction, hydrogen evolution, and oxygen evolution reactions","authors":"Mozhgan Hadavand , Mehdi Mehrpooya , Mohammad Reza Ganjali","doi":"10.1016/j.cartre.2026.100613","DOIUrl":"10.1016/j.cartre.2026.100613","url":null,"abstract":"<div><div>In response to the urgent need for high-performance non-precious metal electrocatalysts to address the energy crisis and reduce dependence on fossil fuels, we propose a novel approach to develop a highly selective and efficient electrocatalyst derived from metal-organic frameworks (MOFs). This electrocatalyst is designed for oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and oxygen evolution reaction (OER). The innovative synthesized catalyst combines the synergistic effects of cobalt (Co), MXene, and lanthanide praseodymium (Pr), which are synthesized via a simple co-precipitation method. Cobalt plays an important role in enhancing electron transfer kinetics, and the layered structure of MXene significantly increases the active surface area, and the lanthanide praseodymium enhances electrical conductivity and structural and chemical stability. All of these help the synthesized catalyst to have a low overvoltage, thereby facilitating ORR, HER, and OER processes. The interaction between these components enhances the catalytic performance and benefits from unique morphological features, abundant heterogeneous interfaces, and excellent structural stability. The synthesized electrocatalysts were characterized using various techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmet-Teller (BET) analysis, along with electrochemical evaluations such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). Two separate samples of 10 %Pr-coreshell ZIF8@ZIF67/Mxene at 1:1 and 2:1 ratios showed exceptional electrocatalytic activity. For ORR, the samples showed impressive onset potentials of 0.904 V and 0.894 V (vs. RHE), while their HER onset potentials were recorded at -0.21 V and -0.20 V (vs. RHE). In terms of OER, the onset potentials were 1.62 V and 1.65 V, respectively. Notably, these materials showed outstanding stability and outperformed commercial Pt/C electrocatalysts, making them promising candidates for sustainable energy solutions.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"23 ","pages":"Article 100613"},"PeriodicalIF":3.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.cartre.2026.100608
A. Naseri , P. Saini , E. Abbasi-Atibeh , J. Shen , M. Secanell , N. Semagina , J.S. Olfert
<div><div>The development of sustainable energy technologies and demand for advanced carbon materials drives innovation in methane pyrolysis, particularly catalytic approaches using ferrocene (Fe(C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>) as a dual catalyst/carbon source. This study investigates methane decomposition in a ferrocene-fed tubular reactor using undiluted CH<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span> at temperatures of 633 to 1046 °C and flow rates of 0.063–0.25 SLPM, corresponding to gas hourly space velocities of approximately 16–65 h<sup>-1</sup>. The reactor achieved conversions of 3%–83% at lower temperatures than for an uncatalyzed reactor, and produced agglomerates of ordered graphitic carbon particles (<span><math><mrow><mn>4</mn><mo>.</mo><mn>34</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>52</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span>) contrasting to the submicron particles in non-catalytic processes. The particles consisted of approximately 57 wt% graphitic carbon and 4 wt% amorphous carbon, with the remaining weight fraction attributed to metal-containing phases, including <span><math><mrow><mi>α</mi><mo>−</mo><mi>F</mi><mi>e</mi></mrow></math></span> and iron carbide, as determined by X-ray diffraction coupled with Rietveld analysis. The highly ordered graphitic layers (interplanar spacing: 3.3 Å) were confirmed by transmission electron microscopy (TEM) while Raman spectroscopy demonstrated reduced defects in catalytic runs (<span><math><mrow><msub><mrow><mi>I</mi></mrow><mrow><mi>D</mi></mrow></msub><mo>/</mo><msub><mrow><mi>I</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>64</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>01</mn></mrow></math></span>) versus non-catalytic (<span><math><mrow><mn>0</mn><mo>.</mo><mn>86</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>16</mn></mrow></math></span>). The increased graphitization of the catalytic carbon was also demonstrated by its thermogravimetric analysis in air, which showed a carbon–iron composite profile with combustion peaks at approximately 637 °C and 670 °C. The catalytic carbon has a high surface area (31 m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span>/g), and high electrical conductivity, <em>i.e.,</em> 3.1 S/cm (in-plane) and 6.5 S/cm (through-plane). Microstructural variability was limited; however, increasing temperature and conversion drove phase evolution, manifested predominantly as graphitic carbon accumulation. Ferrocene lowered reaction temperatures and increased the order, graphitization and size of the formed carbon containing particles (<em>i.e,</em> <span><math><mrow><mn>4</mn><mo>.</mo><mn>34</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>52</mn></mrow></math></span> <span><math><mi>μm</mi></math></span>). Its usage could result in reactors with reduced energy demand, lower operating temperature (allowing for conventional reactor materials to be used), and increased carbon particle s
{"title":"Characterization of carbon derived from ferrocene-catalyzed methane decomposition in a floating catalyst tubular reactor","authors":"A. Naseri , P. Saini , E. Abbasi-Atibeh , J. Shen , M. Secanell , N. Semagina , J.S. Olfert","doi":"10.1016/j.cartre.2026.100608","DOIUrl":"10.1016/j.cartre.2026.100608","url":null,"abstract":"<div><div>The development of sustainable energy technologies and demand for advanced carbon materials drives innovation in methane pyrolysis, particularly catalytic approaches using ferrocene (Fe(C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>) as a dual catalyst/carbon source. This study investigates methane decomposition in a ferrocene-fed tubular reactor using undiluted CH<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span> at temperatures of 633 to 1046 °C and flow rates of 0.063–0.25 SLPM, corresponding to gas hourly space velocities of approximately 16–65 h<sup>-1</sup>. The reactor achieved conversions of 3%–83% at lower temperatures than for an uncatalyzed reactor, and produced agglomerates of ordered graphitic carbon particles (<span><math><mrow><mn>4</mn><mo>.</mo><mn>34</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>52</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span>) contrasting to the submicron particles in non-catalytic processes. The particles consisted of approximately 57 wt% graphitic carbon and 4 wt% amorphous carbon, with the remaining weight fraction attributed to metal-containing phases, including <span><math><mrow><mi>α</mi><mo>−</mo><mi>F</mi><mi>e</mi></mrow></math></span> and iron carbide, as determined by X-ray diffraction coupled with Rietveld analysis. The highly ordered graphitic layers (interplanar spacing: 3.3 Å) were confirmed by transmission electron microscopy (TEM) while Raman spectroscopy demonstrated reduced defects in catalytic runs (<span><math><mrow><msub><mrow><mi>I</mi></mrow><mrow><mi>D</mi></mrow></msub><mo>/</mo><msub><mrow><mi>I</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>64</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>01</mn></mrow></math></span>) versus non-catalytic (<span><math><mrow><mn>0</mn><mo>.</mo><mn>86</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>16</mn></mrow></math></span>). The increased graphitization of the catalytic carbon was also demonstrated by its thermogravimetric analysis in air, which showed a carbon–iron composite profile with combustion peaks at approximately 637 °C and 670 °C. The catalytic carbon has a high surface area (31 m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span>/g), and high electrical conductivity, <em>i.e.,</em> 3.1 S/cm (in-plane) and 6.5 S/cm (through-plane). Microstructural variability was limited; however, increasing temperature and conversion drove phase evolution, manifested predominantly as graphitic carbon accumulation. Ferrocene lowered reaction temperatures and increased the order, graphitization and size of the formed carbon containing particles (<em>i.e,</em> <span><math><mrow><mn>4</mn><mo>.</mo><mn>34</mn><mo>±</mo><mn>1</mn><mo>.</mo><mn>52</mn></mrow></math></span> <span><math><mi>μm</mi></math></span>). Its usage could result in reactors with reduced energy demand, lower operating temperature (allowing for conventional reactor materials to be used), and increased carbon particle s","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"23 ","pages":"Article 100608"},"PeriodicalIF":3.9,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-06DOI: 10.1016/j.cartre.2026.100612
Mohammad Bagher Askari , Parisa Salarizadeh
Supercapacitors have emerged as a promising energy storage technology due to their high-power density, rapid charge/discharge rates, and long cycle life. Among various electrode materials, activated carbon (AC) stands out for its high surface area, tunable porosity, cost-effectiveness, and excellent electrochemical stability. This comprehensive review explores recent advancements in AC-based supercapacitor electrodes, focusing on synthesis methods, structural modifications, and electrochemical performance. The impact of pore structure, surface functionalization, and heteroatom doping on capacitance and charge storage mechanisms is analyzed. Moreover, the modification of AC with conductive polymers, metal oxides, metal sulfides, and other types of carbon-based materials is also reviewed. Some of the issues related to increasing energy density at a reasonable cost of decreased power density and scalability, as well as perspectives on the development of sustainable AC and innovative composite materials, are also presented. This work is expected to contribute to the understanding of supercapacitor electrodes for scientists and engineers in the development of next-generation devices.
{"title":"A review on activated carbon's role in next-generation supercapacitors","authors":"Mohammad Bagher Askari , Parisa Salarizadeh","doi":"10.1016/j.cartre.2026.100612","DOIUrl":"10.1016/j.cartre.2026.100612","url":null,"abstract":"<div><div>Supercapacitors have emerged as a promising energy storage technology due to their high-power density, rapid charge/discharge rates, and long cycle life. Among various electrode materials, activated carbon (AC) stands out for its high surface area, tunable porosity, cost-effectiveness, and excellent electrochemical stability. This comprehensive review explores recent advancements in AC-based supercapacitor electrodes, focusing on synthesis methods, structural modifications, and electrochemical performance. The impact of pore structure, surface functionalization, and heteroatom doping on capacitance and charge storage mechanisms is analyzed. Moreover, the modification of AC with conductive polymers, metal oxides, metal sulfides, and other types of carbon-based materials is also reviewed. Some of the issues related to increasing energy density at a reasonable cost of decreased power density and scalability, as well as perspectives on the development of sustainable AC and innovative composite materials, are also presented. This work is expected to contribute to the understanding of supercapacitor electrodes for scientists and engineers in the development of next-generation devices.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"23 ","pages":"Article 100612"},"PeriodicalIF":3.9,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.cartre.2026.100607
C. Clairotte , C. Akl , V. Malesys , L. Josien , L. Vidal , A. Zaarour , G. Trouvé , V. Tschamber , L. Simon
We present a methodology for the identification and characterization of carbon quantum dots (CQDs) emitted during wood combustion in a domestic heating appliance. CQDs were isolated in the nanometric fraction of particulate matter (PM₀.₁, aerodynamic diameter < 0.1 μm) of the fume using an Electrical Low-Pressure Impactor (ELPI) during both transient log-burning phases and steady-state pellet combustion. Their presence was confirmed by complementary techniques, including SEM, TEM, Raman spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). The PM₀.₁ fraction contains nanocrystalline graphene/graphite domains with an amorphization degree of 13–17%, arising from sp³-type defects within an sp² matrix and contributions from amorphous carbon, as confirmed by C1s XPS spectra. We show that quantitative Raman analysis revealed that a five-component deconvolution of the D and G bands, together with the observation of sloping baselines (indicating an underlying photoluminescence background), provides robust criteria for identifying CQDs. TEM images further demonstrate that CQDs adopt nano-onion morphologies with diameters near the impactor cut-off, consisting of an amorphous core encased in concentric graphitic shells. The measured interplanar spacing of 3.84 Å closely matches values reported for synthetic nano-onions derived from biomass precursors.
{"title":"Identification and characterization of carbon quantum dots in PM1 emitted in smoke from domestic wood combustion","authors":"C. Clairotte , C. Akl , V. Malesys , L. Josien , L. Vidal , A. Zaarour , G. Trouvé , V. Tschamber , L. Simon","doi":"10.1016/j.cartre.2026.100607","DOIUrl":"10.1016/j.cartre.2026.100607","url":null,"abstract":"<div><div>We present a methodology for the identification and characterization of carbon quantum dots (CQDs) emitted during wood combustion in a domestic heating appliance. CQDs were isolated in the nanometric fraction of particulate matter (PM₀.₁, aerodynamic diameter < 0.1 μm) of the fume using an Electrical Low-Pressure Impactor (ELPI) during both transient log-burning phases and steady-state pellet combustion. Their presence was confirmed by complementary techniques, including SEM, TEM, Raman spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). The PM₀.₁ fraction contains nanocrystalline graphene/graphite domains with an amorphization degree of 13–17%, arising from sp³-type defects within an sp² matrix and contributions from amorphous carbon, as confirmed by C1s XPS spectra. We show that quantitative Raman analysis revealed that a five-component deconvolution of the D and G bands, together with the observation of sloping baselines (indicating an underlying photoluminescence background), provides robust criteria for identifying CQDs. TEM images further demonstrate that CQDs adopt nano-onion morphologies with diameters near the impactor cut-off, consisting of an amorphous core encased in concentric graphitic shells. The measured interplanar spacing of 3.84 Å closely matches values reported for synthetic nano-onions derived from biomass precursors.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"22 ","pages":"Article 100607"},"PeriodicalIF":3.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145924891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.cartre.2026.100611
Lorenzo Vergari
The importance of graphite-hydrogen chemical reactions to fusion, fission, and hydrogen storage applications, combined with the rapidly evolving knowledge on the underlying mechanisms, has led to the development of multiple models to describe hydrogen transport in graphite. Significant differences exist among these models, resulting from discrepancies in the modeling assumptions, intended degree of fidelity, and conditions of applicability. This paper attempts at reconciling these apparent differences by providing a comprehensive description of the constitutive equations governing hydrogen transport in graphite at high-temperature, identifying outstanding gaps in knowledge, illustrating how these different models approach them, and proposing alternative analytical formulations grounded on experimental results from hydrogen-graphite studies. Governing equations, closing relations, and simplifying assumptions are discussed for hydrogen transport at the inter-granular and intra-granular level, accompanied by compiled experimental data and illustrated energy diagrams associated to the proposed transport mechanisms. Analytical formulations are provided to reproduce competing hypotheses on the mechanisms, supporting the development of a range of computational models that can enable resolution of outstanding knowledge gaps through comparative testing against experimental data.
{"title":"Analytical models of hydrogen transport in graphite","authors":"Lorenzo Vergari","doi":"10.1016/j.cartre.2026.100611","DOIUrl":"10.1016/j.cartre.2026.100611","url":null,"abstract":"<div><div>The importance of graphite-hydrogen chemical reactions to fusion, fission, and hydrogen storage applications, combined with the rapidly evolving knowledge on the underlying mechanisms, has led to the development of multiple models to describe hydrogen transport in graphite. Significant differences exist among these models, resulting from discrepancies in the modeling assumptions, intended degree of fidelity, and conditions of applicability. This paper attempts at reconciling these apparent differences by providing a comprehensive description of the constitutive equations governing hydrogen transport in graphite at high-temperature, identifying outstanding gaps in knowledge, illustrating how these different models approach them, and proposing alternative analytical formulations grounded on experimental results from hydrogen-graphite studies. Governing equations, closing relations, and simplifying assumptions are discussed for hydrogen transport at the inter-granular and intra-granular level, accompanied by compiled experimental data and illustrated energy diagrams associated to the proposed transport mechanisms. Analytical formulations are provided to reproduce competing hypotheses on the mechanisms, supporting the development of a range of computational models that can enable resolution of outstanding knowledge gaps through comparative testing against experimental data.</div></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"22 ","pages":"Article 100611"},"PeriodicalIF":3.9,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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