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This study considers the influence of purity and surface area on the thermal and oxidation properties of hexagonal boron nitride (h-BN) nanoplatelets, which represent crucial factors in high-temperature oxidizing environments. Three h-BN nanoplatelet-based materials, synthesized with different purity levels and surface areas (~3, ~56, and ~140 m2/g), were compared, including a commercial BN reference. All materials were systematically analyzed by various characterization techniques, including gas pycnometry, scanning electron microscopy, X-ray diffraction, Fourier-transform infrared radiation, X-ray photoelectron spectroscopy, gas sorption analysis, and thermal gravimetric analysis coupled with differential scanning calorimetry. Results indicated that the thermal stability and oxidation resistance of the synthesized materials were improved by up to ~13.5% (or by 120 °C) with an increase in purity. Furthermore, the reference material with its high purity and low surface area (~4 m2/g) showed superior performance, which was attributed to the minimized reactive sites for oxygen diffusion due to lower surface area availability and fewer possible defects, highlighting the critical roles of both sample purity and accessible surface area in h-BN thermo-oxidative stability. These findings highlight the importance of focusing on purity and surface area control in developing BN-based nanomaterials, offering a path to enhance their performance in extreme thermal and oxidative conditions. [ABSTRACT FROM AUTHOR]

In recent nanomaterials research, combining nanoporous carbons with metallic nanoparticles, like palladium (Pd), has emerged as a focus due to their potential in energy, environmental and biomedical fields. This study presents a novel approach for synthesizing Pd-decorated carbons using magnetron sputter deposition. This method allows for the functionalization of nanoporous carbon surfaces with Pd nano-sized islands, creating metal–carbon nanocomposites through brief deposition times of up to 15 s. The present research utilized direct current magnetron sputtering to deposit Pd islands on a flexible activated carbon cloth substrate. The surface chemistry, microstructure, morphology and pore structure were analyzed using a variety of material characterization techniques, including X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, gas sorption analysis and scanning electron microscopy. The results showed Pd islands of varying sizes distributed across the cloth's carbon fibers, achieving high-purity surface modifications without the use of chemicals. The synthesis method preserves the nanoporous structure of the carbon cloth substrate while adding functional Pd islands, which could be potentially useful in emerging fields like hydrogen storage, fuel cells and biosensors. This approach demonstrates the possibility of creating high-quality metal–carbon composites using a simple, clean and economical method, expanding the possibilities for future nanomaterial-based applications. [ABSTRACT FROM AUTHOR]

A nanoporous and large surface area (∼800 m2/g) graphene-based material was produced by plasma treatment of natural flake graphite and was subsequently surface decorated with platinum (Pt) nano-sized particles via thermal reduction of a Pt precursor (chloroplatinic acid). The carbon-metal nanocomposite showed a ∼2 wt% loading of well-dispersed Pt nanoparticles (<2 nm) across its porous graphene surface, while neither a significant surface chemistry alteration nor a pore structure degradation was observed due to the Pt decoration procedure. The presence of Pt seems to slightly promote the hydrogen sorption behavior at room temperature with respect to the pure graphene, thus implying the rise of "weak" chemisorption phenomena, including a potential hydrogen "spillover" effect. The findings of this experimental study provide insights for the development of novel graphene-based nanocomposites for hydrogen storage applications at ambient conditions. Image 1 [ABSTRACT FROM AUTHOR]

Naturally short-length multi-walled Russian-doll-like carbon nanotubes derived by a catalyst-free arc-discharge method were used as nano-sized "cutters" to transform bulk graphitic sheets into thin/few-layered graphene-like nano-sized platelets (GNPs) during a jet milling procedure. A short follow-up oxygen plasma treatment in a plasma reactor further increases the number of smaller (i.e. ∼80 nm) and thinner nanoparticles (i.e. three-layered GNPs) as well as their oxygen content (i.e. up to ∼8 at.%). These oxygen-rich surface-functionalized GNPs are suitable additives for producing stable nanogels as demonstrated by the preparation of carbon ink dispersions. Image 1 [ABSTRACT FROM AUTHOR]

The current paper presents a combined ab initio and experimental study of H 2 adsorption on carbon. Adsorption energetics of a H 2 molecule on pristine graphene were obtained for various molecule orientations, showing that the perpendicular-to-surface orientation is energetically more preferable ( E ads  = −0.076eV/H 2 ) than the parallel orientations ( E ads ≈−0.071eV/H 2 ). Subsequently, B, Co, Ni, Pd, Pt and Ru substituents of a C atom in graphene were considered, leading to the conclusion that Pt and Ru promote the H 2 adsorption by ≈−0.012eV/H 2 . Pt promotes adsorption in all its neighbouring hexagons, while Ru impact is localised to the position directly above the dopant. Pure, Pt and Ru-doped ordered mesoporous carbon samples were evaluated experimentally for their H 2 adsorption performance under a low-pressure regime (up to 1 bar) at cryogenic and room temperatures ( i.e., 77 and 298 K, respectively). These experimental measurements indicated that, while the specific area of the metal-decorated carbons is lower than that of the pristine carbon material, the presence of Pt and Ru nanoparticles leads to a slight improvement of the H 2 uptake performance at room temperature. [ABSTRACT FROM AUTHOR]

The facile, rapid and bulk production of composite materials consisting of carbon nanostructures doped with metal-based compounds has been a significant challenge for various research areas where such types of materials can be applied, including catalysis, energy storage and water purification. In this work, a carbon foam‑aluminum fluoride composite (C-AlF 3 ) was developed by adopting a combustion synthesis approach, which is an attractive alternative to wet chemical methods usually employed for such purposes. The flame ignition and combustion of a solid-state mixture comprising a fluoropolymer and nano-sized Al powder leads to the formation of a porous carbon foam network doped with dispersed cubic-like AlF 3 nanoparticles (100 to 500 nm in size), as observed by high-resolution microscopy methods. Selective area electron diffraction and X-ray diffraction studies revealed a rhombohedral α-AlF 3 crystal structure for these embedded particles, while micro-Raman spectroscopy indicated typical carbonaceous features for the foamy matrix. The C-AlF 3 composite also showed a combination of micro-, meso- and macro-porous characteristics (i.e. pore sizes in the nanometer scale) based on the analysis of N 2 sorption data collected at 77 K. The findings of this study provide useful insights for further research on carbon-based nanocomposite materials prepared via direct combustion synthesis routes. [ABSTRACT FROM AUTHOR]

A nanoporous metal–organic framework material, exhibiting an IRMOF-1 type crystalline structure, was prepared by following a direct solvothermal synthesis approach, using zinc nitrate and terephthalic acid as precursors and dimethylformamide as solvent, combined with supercritical CO 2 activation and vacuum outgassing procedures. A series of advanced characterization methods were employed, including scanning electron microscopy, Fourier-transform infrared radiation spectroscopy and X-ray diffraction, in order to study the morphology, surface chemistry and structure of the IRMOF-1 material directly upon its synthesis. Porosity properties, such as Brunauer–Emmet–Teller (BET) specific area (∼520 m 2 /g) and micropore volume (∼0.2 cm 3 /g), were calculated for the activated sample based on N 2 gas sorption data collected at 77 K. The H 2 storage performance was preliminary assessed by low-pressure (0–1 bar) H 2 gas adsorption and desorption measurements at 77 K. The activated IRMOF-1 material of this study demonstrated a fully reversible H 2 sorption behavior combined with an adequate gravimetric H 2 uptake relative to its BET specific area, thus achieving a value of ∼1 wt.% under close-to-atmospheric pressure conditions. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) nanoplatelets with ~ 99 wt.% purity, 900 to 2000 nm particle width, 30 to 90 nm particle thickness, ~ 213 m 2 /g specific surface area (SSA), ~ 66% micropore SSA and ~ 0.85 nm average pore size were synthesized in a powder form using H 3 BO 3 and CO(NH 2 ) 2 as precursors followed by consecutive thermal treatments under inert and oxidized atmospheres. Thermal gravimetric analysis (TGA) combined with differential scanning calorimetry (DSC), under synthetic air-flow and up to ~ 1300 °C, were employed to evaluate both purity and oxidation resistance of the product directly upon its synthesis. The h-BN powder was collected at the stage of its highest purity which, based on TGA-DSC data, corresponded to an additional heat treatment up to ~ 700 °C. The active oxidation seems to occur in the temperature range between ~ 860 and ~ 1000 °C, followed by formation of B 2 O 3 in the final residue. Subsequently, the purified h-BN powder was extensively characterized for its structure, morphology and porosity using X-ray diffraction, scanning electron microscopy and nitrogen gas adsorption/desorption measurements at 77 K, respectively. As briefly discussed, purity and SSA seem to have a crucial role in the thermal stability and oxidation resistance of BN materials in general. [ABSTRACT FROM AUTHOR]

A novel, one-step, wet-free, environmental friendly and high-yield method for producing few-layer graphene powders with large surface areas (up to 800 m 2 /g) and narrow nanopore sizes (0.7–0.8 nm) using plasma-induced exfoliation of natural graphite is presented. Advanced characterization techniques were employed, including scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and N 2 gas adsorption/desorption measurements at 77 K, to investigate the morphological, elemental, structural and textural/porosity properties of these nanomaterials. Fully reversible H 2 gas adsorption/desorption isotherms with maximum gravimetric capacities of up to ∼2 wt.% at 77 K and ∼60 bar are reported here. The H 2 storage performance at 77 K is well correlated with certain textural features such as specific surface area and microporosity. The results of this work provide a valuable feedback for further research on plasma-processed graphene-based materials towards efficient H 2 storage via cryo-adsorption. [ABSTRACT FROM AUTHOR]

In the present work, a nanoporous (pore width ~ 0.7 nm) graphene-based sponge-like material with large surface area (~ 350 m 2 /g) was synthesized by wet chemical reduction of graphene oxide in combination with freeze-drying. Surface morphology and elemental composition were studied by scanning and transmission electron microscopy combined with energy dispersive X-ray spectroscopy. Surface chemistry was qualitatively examined by Fourier-transform infrared spectroscopy, while the respective structure was investigated by X-ray diffraction analysis. Textural properties, including Brunauer–Emmet–Teller (BET) surface area, micropore volume and surface area as well as pore size distribution, were deduced from nitrogen gas adsorption/desorption data obtained at 77 K and up to 1 bar. Potential use of the spongy graphene for gas storage and separation applications was preliminarily assessed by low-pressure (0–1 bar) H 2 , CO 2 and CH 4 sorption measurements at different temperatures (77, 273 and 298 K). The adsorption capacities for each gas were evaluated up to ~ 1 bar, the isosteric enthalpies of adsorption for CO 2 (28–33 kJ/mol) and CH 4 (30–38 kJ/mol) were calculated using the Clausius–Clapeyron equation, while the CO 2 /CH 4 gas selectivity (up to 95:1) was estimated using the Ideal Adsorbed Solution Theory (IAST). [ABSTRACT FROM AUTHOR]

In the present work, we synthesized and systematically characterized two novel graphene-based nanomaterials, a chemically reduced graphene oxide (GO) sponge and a microwave-exfoliated GO. Textural properties were determined by N 2 adsorption/desorption at 77 K, while additional characterization techniques were employed, such as Micro-Raman Spectroscopy, Field-Emission Scanning Electron Microscopy and High-Resolution Transmission Electron Microscopy, to elucidate further the structural and morphological features. Both nanomaterials were additionally evaluated for their H 2 storage capacity and were critically compared to commercially available carbons (e.g. few-layer graphenes, carbon nanotubes) based on systematic H 2 adsorption/desorption measurements at 77 K between 0 and 1 bar. Maximum H 2 gravimetric capacities of ∼0.5 wt% and ∼0.7 wt% were recorded at 77 K and 1 bar for the reduced GO sponge and the microwave-exfoliated GO, respectively. [ABSTRACT FROM AUTHOR]

High-temperature properties of boron nitride platelets (200–800 nm in width and 30–50 nm in thickness) were systematically evaluated through thermogravimetric analysis (TGA) in combination with differential scanning calorimetry (DSC). X-Ray Diffraction (XRD) studies confirmed the hexagonal graphitic-like structure of the material, while Fourier-Transform Infrared Spectroscopy (FT-IR) indicated the active vibration modes related to the B–N bond. The specific surface area (SSA), calculated by the multi-point Brunauer-Emmet-Teller (BET) method, was determined at ∼23 m 2 /g through N 2 adsorption/desorption measurements at 77 K. Both high-temperature resistance and oxidation behavior were examined from room temperature (25 °C) up to ∼1300 °C under air-flow conditions. The h-BN platelets demonstrated a high thermal stability of up to ∼1000 °C, while their oxidation occurred in the temperature range between 1000 and 1200 °C, followed by the formation of boron oxide (B 2 O 3 ). [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyaniline-derived activated carbon was studied for H 2 storage and supercapacitors. • A known commercial activated carbon with larger pore sizes was used as a reference. • Strong interaction with H 2 and reversible H 2 uptake of ~5.5 wt% at 77 K and ~60 bar. • Excellent electrochemical energy storage behavior using an aqueous CsCl electrolyte. • Smaller pore sizes are responsible for the enhanced performance in both applications. The development and in-depth characterization of multifunctional materials with versatile use in energy and environmental applications has been a topic of on-going investigations. In this work, a nanoporous polymer-/polyaniline-derived activated carbon (PDAC), with large surface area (~2200 m2/g) and large pore volume (~1 cm3/g), was thoroughly studied towards its applicability for H 2 storage and supercapacitor energy storage. The PDAC demonstrated a superior H 2 adsorption performance under cryogenic conditions, reaching a high and fully reversible excess gravimetric H 2 uptake of ~5.5 wt% at 77 K and ~60 bar, along with a ~8.3 kJ/mol heat of adsorption at zero coverage. Furthermore, thin PDAC electrodes with an aqueous CsCl electrolyte were combined in a supercapacitor cell that exhibited a gravimetric capacitance of ~130 F/g for a 0.5 mV/s scanning rate along with a 99% coulombic efficiency and a 100% capacitance retention after 2500 charge/discharge cycles. The PDAC material showed substantially improved H 2 and electrochemical energy storage performance compared to a well-established commercial activated carbon, which is attributed to the overall smaller pore sizes of the PDAC structure. [ABSTRACT FROM AUTHOR]

The European Green Deal has set a target for Europe to achieve net-zero greenhouse gas emissions by 2050, necessitating a transition to more sustainable energy sources. Hydrogen gas (H 2) has emerged as a promising solution, with methane pyrolysis presenting a viable method for its production. This study explores the optimization of methane plasma pyrolysis for hydrogen and high-quality carbon production. Employing a statistical approach by a design of experiment software, critical process parameters are systematically analyzed to predict their impact within a defined range. Additionally, the paper conducts comprehensive characterization of the solid carbon produced during pyrolysis using imaging, spectroscopic and elemental analysis, and gas sorption analysis methods. The experimental investigation was conducted using a thermal plasma reactor with several settings of influential parameters including methane gas (CH 4) content in the plasma gas, electric current, and arc length. The DC-transferred plasma arc is formed using a variable gas mixture of argon gas (Ar) and CH 4, with a constant flow rate of 5 Nl/min. Thirteen tests were designed, evaluating responses such as power input, process stability, and H 2 yield. The H 2 yield indicates the hydrogen produced from CH 4 , with 100% representing total conversion. While the process exhibited inconstancy, attributed to reactor design constraints, a high H 2 yield of 67%–100% was achieved. The results indicate that a higher CH 4 content in the plasma gas and extended arc lengths disturb the plasma arc, hence reducing the H 2 yield. Increased power input, achieved through higher amperage levels, and a wider reaction zone eased by extending the arc length both led to an improved H 2 yield. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) revealed microstructural differences, with carbon samples from the filter exhibiting finer textures and carbon samples from the reactor larger sizes and dendritic particles. Raman spectroscopy confirmed crystalline graphitic-like structures with low defect concentrations, a finding supported by X-ray diffraction (XRD) analysis. Inductively coupled plasma mass spectroscopy (ICP-MS) analysis confirmed high-purity carbon with slight impurities from initial filter contamination. Brunauer-Emmett-Teller (BET) specific surface area calculations based on gas sorption analysis showed significant variations, with filter-collected samples exhibiting 40–170 m2/g and reactor-collected ones showing 7–30 m2/g. [Display omitted] • This study investigates a unique approach to optimizing the thermal plasma pyrolysis of methane. • A H 2 yield of 67%–100% was achieved utilizing a DC-transferred plasma arc furnace and an Ar and CH 4 mixture plasma gas. • A lower CH 4 content in the plasma gas and an optimized arc length improve the plasma arc and the H 2 yield. • The carbon shows crystalline graphitic-like structures with low defect concentrations. [ABSTRACT FROM AUTHOR]

Nanotubes made of boron nitride (BN) and carbon have attracted considerable attention within the literature due to their unique mechanical, electrical and thermal properties. In this work, BN and carbon nanotubes, exhibiting high purity (>99%) and similar surface areas (~200 m2/g), were systematically investigated for their thermal stability and oxidation behavior by combining thermal gravimetric analysis and differential scanning calorimetry methods at temperatures of up to ~1300 °C under a synthetic air flow environment. The BN nanotubes showed a good resistance to oxidation up to ~900 °C and fully transformed to boron oxide up to ~1100 °C, while the carbon nanotubes were stable up to ~450 °C and almost completely combusted up to ~800 °C. The different oxidation mechanisms are attributed to the different chemical nature of the two types of nanotubes. [ABSTRACT FROM AUTHOR]

This study investigates the capability of the Southeast Mesohellenic Trough (SE MHT) sandstone formations to serve as a potential reservoir for CO2 storage in response to the emerging climate change issues by promoting environmentally friendly mineral sequestration applications. Sandstone samples, for the first time, were evaluated for their petrographic characteristics, mineral chemistry, geochemical properties, as well as their petrophysical and gas adsorption properties through tests. The sandstones were tested and classified into distinct groups. The most promising site to be considered for pilot CO2 storage testing is the Pentalofos Formation locality since its sandstones display specific mineral phases with the proper modal composition to conceivably react with injected CO2, leading to the development of newly formed and stable secondary mineral phases. The gas adsorption results are also more encouraging for sandstones from this sedimentary formation. All the measured UCS (uniaxial compressive strength), Ei (bending stiffness), and ν (Poisson's ratio) results are above those dictated by international standards to perform CO2 storage practices safely. Furthermore, the specified targeted locality from the Pentalofos Formation holds the geological advantage of being overlaid by an impermeable cap-rock formation, making it suitable for deploying CO2 mineralization practices. The demarcated area could permanently store a calculated amount of ~50 × 105 tons of CO2 within the geological reservoir by reacting with the specified mineral phases, as specified through the proposed petrographic PrP index (potential reactive phases). [ABSTRACT FROM AUTHOR]

[Display omitted] • MnO 2 /PAC composite synthesized hydrothermally; PAC derived from pyrolysis. • PAC/β-MnO 2 nanorods excel in electrochemical performance with high surface area, mesoporous structure, and efficient ion diffusion. • MnO 2 /PAC composite showed 208.75 F g−1 capacitance at 0.5 A g−1 and 87.43% cyclic stability in neutral aqueous electrolyte. • The PAC//PAC/MnO 2 ASC shows 279 F g−1 capacitance at 0.5 A g−1 in a 1.4 V potential window. • The ASC boasts 23.3 Wh kg−1 energy density, 350.4 W kg−1 output power density, and 90.3% capacitance retention after 6000 cycles. In this study, we present the electrochemical performance of an asymmetric supercapacitor (ASC) composed of one-dimensional manganese oxide (MnO 2) nanorods embedded in porous activated carbon sheets (MnO 2 /PAC) as the positive electrode (positrode), and renewable porous activated carbon (PAC) as the negative electrode (negatrode). This configuration facilitates a high rate of charge/discharge while maintaining substantial specific capacity. The MnO 2 /PAC composite was successfully synthesized using a hydrothermal technique, while the PAC material was produced through pyrolysis reaction. The MnO 2 /PAC composite exhibited a maximum specific capacitance of 208.75F g−1 at 0.5 A/g and demonstrated a cyclic stability of 87.43 % in neutral aqueous electrolytes. This notable electrochemical performance is attributed to the significant contribution of the high pseudo-capacitance offered by dense MnO 2 nanorods, in addition to the expansive surface area of the activated carbon sheets with closely packed structures. The ASC constructed as PAC//MnO 2 /PAC displayed a high energy density of 23.3 Wh kg−1 and a power density of 350.4 W kg−1 at a current density of 0.5 A/g. Furthermore, the device showcased exceptional cycling stability, retaining 90.3 % at a current density of 4 A/g. These results underscore the substantial untapped potential of ASC devices for innovative applications in advanced energy storage. [ABSTRACT FROM AUTHOR]

This study reports on the low-pressure hydrogen (H 2) and deuterium (D 2) physisorption processes in nanoporous activated carbon cloth at supercritical temperatures. In-situ small-angle neutron scattering (SANS) is employed as a hydrogen-sensitive method to determine the pore-size-dependent and isotope-dependent adsorbate densification for different gas pressures up to 1 bar. The changes of the SANS signal resulting from the physisorption of adsorbate molecules in the pore space is described by analytical pore scattering functions resembling slit-like pores. Analysis based on a hierarchical pore model allows quantifying the pore-size-dependent physical density of the confined adsorbate for three pore classes, resembling roughly the IUPAC classes of ultramicropores, supermicropores, and mesopores. While the adsorbate density within the very smallest pores approaches the bulk solid density of H 2 for pressures of about 1 bar at 77 K, it remains much lower for larger pores. A high density is also found for D 2 within ultramicropores, but these results are hampered by a subtle effect of an exchange of chemically bound hydrogen by deuterium in the sample. These findings contribute to a fundamentally better understanding of confinement effects on hydrogen densification, and affect materials design for efficient hydrogen storage devices working at realistic cryogenic conditions and low pressures. [Display omitted] • Quantification of density evolution of H 2 and D 2 adsorbed in nanoporous activated carbon cloth at supercritical temperatures. • Hierarchical model of slit-like pores for SANS data reveals pore-size-dependent adsorbate densification. • Adsorbate density in pores smaller than 0,7 nm approaches bulk solid density at 77 K and ambient pressure. [ABSTRACT FROM AUTHOR]

The adsorption of actinide ions (Am(III) and U(VI)) from aqueous solutions using pristine and oxidized carbon fabrics was investigated by means of batch experiments at different pH values (pH 4, 7 and 9) and temperatures (25, 35 and 45 °C) under ambient atmospheric conditions. The experimental results indicated that both the pH and the fabric texture affected the adsorption rate and the relative removal efficiency, which was 70% and 100% for Am(III) and U(VI), respectively. The Kd (L/kg) values for U(VI) were generally found to be higher (2 < log10(Kd)< 3) than the corresponding values for Am(III) adsorption (1.5 < log10(Kd) < 2). The data obtained from the experiments regarding the temperature effect implied that the relative adsorption for both actinides increases with temperature and that adsorption is an endothermic and entropy-driven reaction. The application of the fabrics to remove the two actinides from contaminated seawater samples showed that both the relative removal efficiency and the Kd values decreased significantly due to the presence of competitive cations (e.g., Ca2+ and Fe3+) and complexing anions (CO32−) in the respective waters. Nevertheless, the removal efficiency was still remarkable (50% and 90% for Am(III) and U(VI), respectively), demonstrating that these materials could be attractive candidates for the treatment of radionuclide/actinide-contaminated waters. [ABSTRACT FROM AUTHOR]

Coffee, as one of the most traded resources, generates a vast amount of biogenic by-products. Coffee silver skins (CSS), a side stream from the roasting process, account for about 4 wt.%. Despite the abundancy of CSS, possible routes to generate added value for broad applications are limited. Herein, we present an approach to use CSS as a precursor material for supercapacitor electrodes. KOH activated carbon (AC) was produced from CSS. The resulting AC—CSS was characterized by X-ray diffraction, gas sorption analysis, scanning electron microscopy, and Raman spectroscopy. The highly porous AC—CSS exposes a specific surface area of more than 2500 m2 g−1. Electrodes formed with AC—CSS were electrochemically characterized by performing cyclic voltammetry and galvanostatic cycling. The electrodes were further assembled into a supercapacitor device and operated using 1 M sulfuric acid as electrolyte. In addition, various quinones were added to the electrolyte and their impact on the capacitance of AC—CSS electrodes was analyzed. In this work, we were able to show that CSS are a valuable source for supercapacitor applications and that coffee-waste-derived quinones can act as capacitance enhancers. Thus, the findings of this research show a valuable path towards sustainable and green energy storage solutions. [ABSTRACT FROM AUTHOR]

This study represents the first assessment of CO 2 storage potential in Austrian coal seams. Coal samples were taken from Fohnsdorf and Leoben abandoned coal mines, with particular emphasis on the Fohnsdorf coal since Leoben coal reserves were largely mined during previous coal production. Several methods were used to compare coal characteristics, including Rock-Eval pyrolysis (RE), organic petrography, and low-pressure N 2 and CO 2 sorption measurements. Both Fohnsdorf and Leoben coal samples show low sulfur and ash yields, as well as correspondingly high total organic carbon (TOC) contents. The pyrolysis T max and vitrinite reflectance values agree with a low coal rank for both sites. According to the N 2 adsorption measurements at 77 K, low-lying mire coals from Fohnsdorf show a higher BET-specific surface area (BET-SSA) and BJH pore volume compared to raised-mire coals from Leoben. However, sapropelic shales and high-ash coals from Leoben show the highest BET-SSA and BJH pore volumes of all investigated samples and considerably exceed the N 2 adsorption volumes of pure coals from both locations (N 2 uptake up to 16 cm3/g; avg. for all samples 5.4 cm3/g). In contrast, the mean adsorbed CO 2 uptake measured at 273 K and ∼ 1 bar followed the order of Fohnsdorf low-lying mire coals > Leoben raised-mire coals > Leoben sapropelic coals and shales, ranging at ∼0.8 mmol/g, ∼0.7 mmol/g, and ∼ 0.2 mmol/g, respectively. This shows that BET-SSA and BJH equations did not allow for adequate estimation of CO 2 adsorption capacity trends in the investigated sample set. Furthermore, based on the existence of a hysteresis loop between CO 2 adsorption and desorption branches for all investigated samples, the occurrence of weak chemisorption phenomena during CO 2 adsorption is indicated. This effect helps to increase CO 2 uptake and storage safety since the chemisorption process is not fully reversible upon pressure decrease. Ultimately, the theoretical CO 2 sequestration potential of the remaining unmined Fohnsdorf coal reserves was estimated at 4.65 million tons, with an additional potential for enhanced coal bed methane production due to the gas-rich nature of Fohnsdorf coals with an estimated 1.2 billion m3 of CH 4 in place. [ABSTRACT FROM AUTHOR]

Self-propagating exothermic reactions, for instance in the nickel-aluminum (Ni–Al) system, have been widely studied to create high performance intermetallic compounds or for in-situ welding. Their easy ignition once the phase spacing is reduced below the micron scale, makes top-down methods like high-energy ball milling, ideal to fabricate such reactive nanostructures. A major drawback of ball milling is the need of a sintering step to form bulk pieces of the reactive material. However, this is not possible, as the targeted reactions would already proceed. Therefore, we investigate the ability of high pressure torsion as an alternative process, capable to produce bulk nanocomposites from powder mixtures. Severe straining of powder mixtures with a composition of 50 wt% Ni and 50 wt% Al enables fabrication of self-reactive bulk samples with microstructures similar to those obtained from ball milling or magnetron sputtering. Samples deformed at ambient temperature are highly reactive and can be ignited significantly below the Al melting point, finally predominantly consisting of Al 3 Ni 2 and Al 3 Ni, independent of the applied strain. Although the reaction proceeds first at the edge of the disk, the strain gradient present in the disks does not prevent reaction of the whole sample. • Bulk nanocomposites of nickel and aluminum are successfully produced by high pressure torsion. • All samples are perfectly ignitable and the reactions are self-propagating throughout the sample. • Reaction sequences and products are studies in-situ with synchrotron experiments. • The effect of heating rate on the reaction sequences and products is studied. [ABSTRACT FROM AUTHOR]

Abstract This research introduces dynamic modeling and real-time control of fractal structure in particulate materials fabricated by the ball milling process, specifically addressing challenges of unavailable real-time non-destructive and non-invasive imaging measurements in the enclosed rotating vials. A description of the internal temperature dynamics in the container is established along with a thermal regulator based on external temperature feedback. The fractal dimension is introduced as a structural measure, and its dynamics is established via an analytical formulation through a lumped model, along with a full thermostructural computational model of the ball milling particulate microstructure. These models are used as real-time observers of inaccessible internal states during the process. In addition, they are used as model references in an adaptive control system, regulating the fractal structure with adaptation via external temperature measurements, available experimentally via an infrared thermocouple. The controller is designed on the basis of the dynamic models and is tested experimentally. The controller is demonstrated to command the duration of the process at steady conditions to obtain the necessary thermal exposure yielding the desired microstructure for the ball-milled particulates. Graphical Abstract Highlights • Thermostructural modeling and regulation of ball milling is investigated to address challenges of unavailable measurements • An adaptive control system for the ball milled particulate microstructure was introduced and tested in the laboratory • The control scheme was designed based on heat transfer and fractal structure dynamics of the process • Adaptation was achieved by comparison of the temperature predictions of the model to infrared thermal measurements • The system achieves the desired refinement in ball milled particulate microstructure by controlling process duration [ABSTRACT FROM AUTHOR]

Abstract Significant efforts have been focused on the search of earth-abundant elements to solve growing energy issues and to provide bifunctional behavior for both hydrogen and oxygen evolution reaction. Mixed transition metals could provide promising synergistic electrochemical properties and serve as bi-catalyst for overall water splitting process. In this study, a needle grass array of nanostructured nickel cobalt sulfide (NiCo 2 S 4) was synthesized using a hydrothermal process. The synthesized NiCo 2 S 4 electrodes showed promising electrocatalytic activity with a low overpotential of 148 mV and 293 mV for hydrogen and oxygen evolution reactions, respectively. The electrolyzer cell consisting of two NiCo 2 S 4 electrodes displayed excellent performance with high electrochemical stability and low overall cell potential of 1.61 V to achieve a current density of 10 mA/cm2. Our study suggests that mixed transition metal chalcogenides such as NiCo 2 S 4 could be used as efficient and stable electrocatalyst for overall water splitting process. Graphical abstract Unlabelled Image Highlights • A needle grass array of nanostructured nickel cobalt sulfide (NiCo 2 S 4) was synthesized using a hydrothermal process. • NiCo 2 S 4 electrodes showed promising electrocatalytic activity. • The electrolyzer cell displayed excellent performance with high electrochemical stability. [ABSTRACT FROM AUTHOR]

This work establishes a computationally efficient model of temperature and diffusion dynamics in ball milled bimetallic Ni-Al particulates. Mechanical contact conditions between adjacent bimetallic domains and temperature fields generated upon impact define the diffusive fluxes through the domains' interfaces. The concentration distributions are studied via Green's function methods, by defining mirror images which reflect the boundary diffusive resistance conditions. Predictions of the model are validated against experimental open-loop scanning electron micrographs and X-ray diffraction spectra at steady-state. Dynamic models of diffusion saturation and internal temperature are developed for the design of closed-loop controller via simulation. This feedback controller is implemented on a laboratory device, equipped with infrared thermometry for external vial temperature measurement, as a self-tuning regulator. The controller adapts an efficiency parameter of the model that thus serves as a real-time observer for internal temperature and diffusion saturation, which are physically inaccessible during processing. Experimental open-loop results are employed to set thresholds of diffusion penetration to avoid early exothermic reaction during fabrication. By controlling the process duration, the regulation system successfully reproduces the material composition of the open-loop reference tests, to ensure desired thermodynamic properties of the ball milled products and safety of the operation. [ABSTRACT FROM AUTHOR]

The Songliao Basin is an important hydrocarbon province of Northeastern China and has a long history of conventional oil and gas production. Nowadays, unconventional resource estimation becomes increasingly important and particularly shale oil/gas production from mature source rocks in the Central Depression may be of great relevance for the regional exploration strategy. The Qingshankou Formation is a promising source rock reservoir. However, for shale oil/gas production to be successful, a refined understanding of the distribution of hydrocarbons within the low-permeable rocks, as well as the timing of hydrocarbon expulsion and its linkage to changing pore characteristics, are key requirements. Therefore, a multi-analytical geochemical and porosity study was conducted on a set of 12 oil-prone, alginite-rich samples from a depth range from 200 to 2500 m in order to understand the linkage of burial compaction, hydrocarbon generation and pore evolution. Macro- (>50 nm) and mesopores (2–50 nm) were investigated by a combination of nitrogen gas adsorption/desorption measurements at 77 K and broad ion beam – scanning electron microscopy. The adsorption tests were conducted on samples before and after solvent-extraction in order to study the effects of soluble organic matter (OM) on pore distributions. These data were compared with organic petrographical observations, bulk geochemical parameters before and after extraction, as well as extract yields from the bulk source rock in order to link structural and geochemical changes in the interval from immature to late peak oil mature (0.4–0.9 %Rr). Total SEM-visible macro- and mesoporosity (φ BIB) is generally limited, but a weak trend of total φ BIB with quartz contents indicates the importance of brittle minerals for pore preservation. A depth trend towards smaller average pore sizes, higher pore aspect ratios, as well as preferentially bedding-parallel pore orientations reflects burial compaction. An observable deficiency of pores <100 nm in φ BIB size distributions, as well as differential BJH mesopore volumes of up to 20% (original vs. extracted), show that pore occlusion by high-molecular weight bitumen changes the apparent pore characteristics particularly for samples from the oil window. A maximum of extractable organic matter (EOM), soluble S2 bitumen , S1 normalized to total organic carbon (TOC) contents, as well as saturated vs. aromatic compound ratios determined from source rock extracts, is reached at a vitrinite reflectance of 0.8 %Rr. An interpreted maximum of shale oil in place at ~0.8 %Rr is followed by a decline in these parameters for the samples at slightly higher thermal maturity (0.9 %Rr). This may indicate the onset of hydrocarbon expulsion at >0.8 %Rr, corresponding with a decrease in the differential BJH volume and less visible pre-oil solid bitumen. The gas storage and retention behavior of the investigated shales may abruptly change with ongoing thermal maturation, as matrix pores are liberated from occluding hydrocarbons. • The hydrocarbon retention properties of the Qingshankou Formation are critical to the evaluation of shale oil potential in the Songliao Basin. • A maximum of shale oil stored in occluded mesopores occurs at ~0.8 %Rr. • At higher maturities, the occluding hydrocarbons are released, resulting in drastically changing pore characteristics. • Differential adsorption tests before and after solvent-extraction enable the quantification of the occlusion effect and the amount of retained hydrocarbons. [ABSTRACT FROM AUTHOR]

Multifunctional materials for energy conversion and storage could act as a key solution for growing energy needs. In this study, we synthesized nanoflower-shaped iron-nickel sulfide (FeNiS) over a nickel foam (NF) substrate using a facile hydrothermal method. The FeNiS electrode showed a high catalytic performance with a low overpotential value of 246 mV for the oxygen evolution reaction (OER) to achieve a current density of 10 mA/cm2, while it required 208 mV at 10 mA/cm2 for the hydrogen evolution reaction (HER). The synthesized electrode exhibited a durable performance of up to 2000 cycles in stability and bending tests. The electrolyzer showed a lower cell potential requirement for a FeNiS-Pt/C system (1.54 V) compared to a standard benchmark IrO2-Pt/C system (1.56 V) to achieve a current density of 10 mA/cm2. Furthermore, the FeNiS electrode demonstrated promising charge storage capabilities with a high areal capacitance of 13.2 F/cm2. Our results suggest that FeNiS could be used for multifunctional energy applications such as energy generation (OER and HER) and storage (supercapacitor). [ABSTRACT FROM AUTHOR]

To contribute to solving global energy problems, a multifunctional CoFe2O4 spinel was synthesized and used as a catalyst for overall water splitting and as an electrode material for supercapacitors. The ultra-fast one-step electrodeposition of CoFe2O4 over conducting substrates provides an economic pathway to high-performance energy devices. Electrodeposited CoFe2O4 on Ni-foam showed a low overpotential of 270 mV and a Tafel slope of 31 mV/dec. The results indicated a higher conductivity for electrodeposited compared with dip-coated CoFe2O4 with enhanced device performance. Moreover, bending and chronoamperometry studies suggest excellent durability of the catalytic electrode for long-term use. The energy storage behavior of CoFe2O4 showed high specific capacitance of 768 F/g at a current density of 0.5 A/g and maintained about 80% retention after 10,000 cycles. These results demonstrate the competitiveness and multifunctional applicability of the CoFe2O4 spinel to be used for energy generation and storage devices. [ABSTRACT FROM AUTHOR]