Hydrothermal carbonization (HTC) is widely regarded as a sustainable route for converting biomass into carbon materials; however, the formation mechanisms of structurally diverse biomass feedstocks remain insufficiently understood. This work systematically investigates HTC reaction pathways of both solid and liquid products using wheat straw (second-generation biomass), wet corn gluten feed (first-generation by-product), and sugars as model systems under varying pH, temperature, and residence time, while directly linking structural evolution of the solids to their electrochemical applicability. A key novelty is the comprehensive, quantitative analysis of liquid filtrates by 1D- and 2D-NMR spectroscopy, enabling access to possible green platform chemicals (levulinic acid, 3-hydroxypyridine, furfurals) as well as considerations regarding toxicology for downstream processing. 3-Hydroxypyridine derivatives form the main N-containing molecular motif in the filtrate, likely formed via Strecker degradation of amino acids with C5-sugar-derived diketones-confirmed through model reactions of C5 and C6 sugars with glycine. Overall, HTC as a pretreatment before pyrolysis increases the carbon content, sp(2)/sp(3) ratio, and bulk conductivity due to increased interparticle connectivity of sugar-derived hydrochar, while reducing alkali contaminants (<0.1 wt%) compared to direct pyrolysis of the biomass. As a proof of concept, selected pyrolyzed carbons are decorated with Pt nanoparticles and exhibit oxygen reduction reaction activity, electrochemical surface area, and kinetic currents approaching those of commercial Pt/C catalysts on a rotating disk electrode, indicating their potential as catalyst supports while highlighting the surface area-conductivity trade-off that limits their applicability.

Abstract The pursuit of green hydrogen production highlights a persistent gap in electrocatalyst research: while academic efforts prioritize cost-efficiency via activity enhancement, industrial viability demands greater emphasis on electrochemical stability. Carbon-based electrocatalysts, particularly those incorporating transition metals, have shown promise in alkaline oxygen evolution (OER) due to their high activity, cost-efficiency, and resource-efficiency. However, these catalysts suffer from insufficient stability under oxidizing conditions compared to pure transition metal catalysts due to erosion of the carbon support resulting from carbon corrosion, among other degradation mechanisms. In this systematic study, the influence of ultra-low amounts (<1 wt %) of iron, cobalt, nickel, and their most common combinations on the stability of a hydrothermally derived, N-doped carbon support and the overall catalyst performance during alkaline OER is systematically explored. By identifying critical stability descriptors and correlating them with synthesis conditions and catalyst properties, primary and secondary corrosion pathways are unraveled. Subsequently, through careful adjustment of carbonization temperature and composition of incorporated transition metals, overall catalyst corrosion can be suppressed immensely. Especially, the inclusion of Ni and Fe is paramount for the formation of stable catalyst materials under laboratory conditions (10 mA/cm2 in 0.1 M KOH), which is surprisingly unconstrained by the degree of graphitization of the carbon support. Mixing this electrochemically stable material with a graphitic carbon powder results in an excellent stability of over 400 h at 100 mA/cm2 in 1 M KOH, implying great potential for the future improvement of carbon-based electrodes under oxidizing conditions toward industrial application.

Carbon materials are promising to fulfill the worldwide need for advanced materials in many areas, particularly in electrochemical applications. However, achieving both high conductivity and surface functionalization in carbon electrodes remains a significant challenge. Herein, a scalable, sustainable, binder-free carbon disc electrode is developed in the desired size and shape. Subsequent femtosecond laser treatment introduces surface functionalization with pyrrolic and pyridinic nitrogen species (up to 12.6 at%, as determined by X-ray photoelectron spectroscopy) while preserving the bulk crystallinity and conductivity of the electrode. The laser-treated surfaces exhibit superhydrophilicity (water contact angle of 0 degrees) and oleophilicity (0 degrees for n-heptane, 25 degrees for n-heptadecane), enabling enhanced interaction with electrolytes and anchoring of metal species like iron ions. Electrochemical impedance spectroscopy confirms minimal resistance (<= 10 Omega) in 0.1M KOH, even after functionalization. The functionalized electrodes demonstrate improved stability in oxygen evolution reaction tests, with laser-treated samples showing 300-500 mV higher activity than untreated counterparts when Fe-impregnated. This work establishes a simple, industrial-scale method for creating multifunctional carbon electrodes with tailored surface properties, bridging the gap between material sustainability and electrochemical performance.

The performance of heterogeneous catalysts is governed by their physicochemical surface properties, requiring respective engineering strategies. Pulsed laser defect engineering in liquid (PUDEL) has emerged as a scalable green technology to activate and dope oxide‐based catalysts. This study investigates UV‐PUDEL effects on the catalytic activity and nanostructure of metallic, colloidal platinum nanoparticles (Pt NPs). As will be shown, the Pt NP size and polydispersity were maintained after UV‐PUDEL, while the zeta potential and hence surface charge density increased by 40%. X‐ray photoelectron spectroscopy (XPS) revealed ∼33% surface‐near platinum oxidation, unaffected by UV‐PUDEL. Control experiments using radical scavengers and nitrogen‐saturated water support the hypothesis that radical oxygen species (ROS) drive these effects. Electrocatalytic studies demonstrated an almost twofold electrochemically active surface area (ECSA) and improved oxygen reduction reaction (ORR) activity of the Pt/C catalysts when UV‐PUDEL was applied to the Pt NPs prior to the carbon deposition. In contrast, a direct laser processing of Pt/C resulted in an activity loss due to a ROS‐induced carbon degradation. Mechanistic insights suggest that the laser‐induced ROS formation is directly linked to the Pt NP. These findings establish UV‐PUDEL as a scalable post‐processing strategy to enhance the catalytic activity of oxide and metal‐based catalysts.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Phase relations in Cr 3 S 4 and the substituted system Cr 3 S 4– x Se x are studied to determine the influence of chemical substitutions on the thermoelectric properties. In addition to the expected equilibrium phase crystallizing in the monoclinic space group I 2/ m , some samples exhibit a defect phase with Cr 2 S 3 -like structure. The defect phase can be observed in a few samples prior to sintering, with the majority being phase-pure Cr 3 S 4 . The defect phase can, however, be introduced in phase-pure samples through in situ heating. It can be proven that the defect phase has an influence on the thermoelectric properties, by lowering the electrical and thermal conductivity, while increasing the Seebeck coefficient. Substitution in the anion lattice of Cr 3 S 4 with Se lowers the thermal conductivity. The improvement is mainly achieved through a reduction of the electronic contribution to the thermal conductivity, leading to total values as low as 1.6 Wm −1  K −1 for the substituted system in comparison to the pristine material 2.3 Wm −1  K −1 .

Phase relations in Cr3S4 and the substituted system Cr3S4–x Se x are studied to determine the influence of chemical substitutions on the thermoelectric properties. In addition to the expected equilibrium phase crystallizing in the monoclinic space group I2/m, some samples exhibit a defect phase with Cr2S3‐like structure. The defect phase can be observed in a few samples prior to sintering, with the majority being phase‐pure Cr3S4. The defect phase can, however, be introduced in phase‐pure samples through in situ heating. It can be proven that the defect phase has an influence on the thermoelectric properties, by lowering the electrical and thermal conductivity, while increasing the Seebeck coefficient. Substitution in the anion lattice of Cr3S4 with Se lowers the thermal conductivity. The improvement is mainly achieved through a reduction of the electronic contribution to the thermal conductivity, leading to total values as low as 1.6 Wm−1 K−1 for the substituted system in comparison to the pristine material 2.3 Wm−1 K−1.

The new thiostannate Na4Sn2S6 was prepared by directed crystal water removal from the hydrate Na4Sn2S6 center dot 5H(2)O at moderate temperatures. While the structure of the hydrate comprises isolated [Sn2S6](4-) anions, that of the anhydrate contains linear chains composed of corner-sharing SnS4 tetrahedra, a structural motif not known in thiostannate chemistry. This structural rearrangement requires bond-breakage in the [Sn2S6](4-) anion, movements of the fragments of the opened [Sn2S6](4-) anion and Sn-S-Sn bond formation. Simultaneously, the coordination environment of the Na+ cations is significantly altered and the in situ formed NaS5 polyhedra are joined by corner- and edge-sharing to form a six-membered ring. Time-dependent in situ X-ray powder diffraction evidences very fast rehydration into Na4Sn2S6 center dot 5H(2)O during storage in air atmosphere, but recovery of the initial crystallinity requires several days. Impedance spectroscopy demonstrates a mediocre room-temperature Na+ ion conductivity of 0.31 mu S cm(-1) and an activation energy for ionic transport of E-a=0.75 eV.

This review article deals with the challenge to identify catalyst materials from literature studies for the ammonia decomposition reaction with potential for application in large-scale industrial processes. On the one hand, the requirements on the catalyst are quite demanding. Of central importance are the conditions for the primary reaction that have to be met by the catalyst. Likewise, the catalytic performance, i.e., an ideally quantitative conversion, and a high lifetime are critical as well as the consideration of requirements on the product properties in terms of pressure or by-products for potential follow-up processes, in this case synthesis gas applications. On the other hand, the evaluation of the multitude of literature studies poses difficulties due to significant varieties in catalytic testing protocols.

Abstract We present the convenient synthesis and characterization of the new ternary thiostannate Na4SnS4 (space group I41/acd ) by directed removal of crystal water molecules from Na4SnS4⋅14 H2O. The compound represents a new kinetically stable polymorph of Na4SnS4, which is transformed into the known, thermodynamically stable form (space group P4‾21c ) at elevated temperatures. Thermal co‐decomposition of mixtures with Na3SbS4⋅9 H2O generates solid solution products Na4−x Sn1−x Sb x S4 (x=0.01, 0.10) isostructural to the new polymorph (x=0). Incorporation of Sb5+ affects the bonding and local structural situation noticeably evidenced by X‐ray diffraction, 119Sn and 23Na NMR, and 119Sn Mössbauer spectroscopy. Electrochemical impedance spectroscopy demonstrates an enormous improvement of the ionic conductivity with increasing Sb content for the solid solution (σ 25°C=2×10−3, 2×10−2, and 0.1 mS cm−1 for x=0, 0.01, and 0.10), being several orders of magnitude higher than for the known Na4SnS4 polymorph.

The effects of low-level partial cation substitution in Cr2−xMxS3 with M = Ti, V or Sn and x = 0.05 and 0.1 have been investigated regarding the long- and short-range crystal structures and thermoelectric properties. All substituted compounds crystallized in the equilibrium phase of Cr2S3, adopting the space group R $${\overline{\text{3}}}$$ . Electron beam irradiation led to a phase transformation from space group R $${\overline{\text{3}}}$$ to P $${\overline{\text{3}}}$$ 1c with a subsequent appearance of diffuse scattering, indicating short-range ordering of cations in the partially occupied cation layers. Substitution of Cr by V led to a reduction in electrical conductivity and subsequently to a lower thermoelectric performance in comparison to the pristine material. In contrast, substitution with Ti yielded an improvement of the performance due to a higher electrical conductivity and a reasonably high Seebeck coefficient. Both Sn-substituted compounds contained only traces of Sn. Surprisingly, a significant improvement of the electrical conductivities could be observed in comparison to the pristine material as well as the other Cr2−xMxS3 materials.

Here, we report on the time dependence of a synthesis procedure for generation of both n- and p-type bismuth telluride-based materials. To initiate the reaction, the starting materials were first mechanical pre-reacted. The Rietveld refinements of X-ray diffraction (XRD) data collected after different milling times demonstrate that Bi2Te3 was formed after only 10 min, and longer milling times do not alter the composition. To complete the phase formation, the powders were treated by field-assisted sintering and heat treatment afterwards. The effect of this fast procedure on the structural and thermoelectric properties was investigated. Samples were obtained with relative densities above 99%. A clear preferred orientation of the crystallites in the samples is evidenced by Rietveld refinements of XRD data. The thermoelectric characteristics demonstrate a good performance despite the short milling time. Further, it was demonstrated for this fast synthesis that the physical transport properties can be varied with well-known n- and p-type dopants like CHI3 or Pb. For these non-optimized materials, a ZT value of 0.7 (n-type) and 0.9 (p-type) between 400 and 450 K was achieved. The long-term stability is demonstrated by repeated measurements up to 523 K showing no significant alteration of the thermoelectric performance.

The influence of low‐level metal cation substitution in the thermoelectric material NiCr2S4, treated via field‐assisted sintering, is investigated in X‐ray diffraction (XRD) and transmission electron microscopy (TEM) studies. NiCr2S4 and Mn0.1Ni0.9Cr2S4 can be synthesized and compacted as phase‐pure pellets, while In0.1Ni0.9Cr2S4 appears as a mixture of different phases. XRD investigations reveal that Mn can be incorporated into the host material's Ni lattice sites, while In is mainly incorporated into additional phases. Both NiCr2S4 and Mn0.1Ni0.9Cr2S4 form a structure of chemically segregated, nanoscale domains, which appear significantly more pronounced for Mn0.1Ni0.9Cr2S4. All materials exhibit similar, promising thermal conductivities around 2.0 W m−1 K−1, with Seebeck coefficients ranging from −55 to −65 μV K−1. Only the electrical conductivity is noticeably influenced by the substitutions, with the highest value of 504 S cm−1 obtained for the pristine material, and subsequently declining for both substituted phases.

The first Pd2+ containing polyoxoniobate [Pd(cyclam)](5){H3Nb6O19}(2) . 26H(2)O (I) was prepared at room temperature. In the structure, two hexaniobate clusters are surrounded by a bi-capped cube formed by Pd2+ centered complexes. This motif is arranged in a layer-like fashion with crystal water molecules located between cations and anions. Temperature resolved in-situ X-ray diffraction experiments demonstrate that successive removal of the crystal water molecules leads to formation of several crystalline intermediate phases. Water sorption investigations show that thermally removed H2O can be successfully reintegrated proceeding via two distinct steps. The catalytic performance for the light-driven hydrogen evolution reaction (HER) was investigated in a sacrificial system and fluorescein Na+ salt as sensitizer yielding a high value of 90 mu mol/h H-2. Surprisingly, a composite Pd@Na-7[HNb6O19] . 15H(2)O is in-situ formed during the catalytic reaction by cation exchange with simultaneous reduction of Pd2+ nanoparticles decorating the hexaniobate support. The recovered catalyst was even more active producing 157 mu mol/h H-2 with an apparent quantum efficiency of 1.85 %. Photocatalytic experiments performed with ex-situ generated Pd nanoparticles deposited on Na-7[HNb6O19] . 15H(2)O show much lower activities indicating a synergistic effect of the in-situ generated Pd@Na-7[HNb6O19] . 15H(2)O catalyst.

The solvothermal reaction of an aqueous solution of Na3SbS3 or Schlippe's Salt (Na3SbS4·9H2O) in the presence of Mn(ClO4)2·6H2O and terpy (terpy = 2,2':6',2''‐terpyridine) or the [Mn(terpy)]2+ complex led to crystallization of the new compound [Mn(terpy)Sb2S4]n (I). The unique crystal structure of I features chains formed by fused MnSb4S5 rings. The Mn2+ cation is coordinated by one terpy ligand and two S2– anions resulting in a distorted MnN3S2 trigonal bipyramid. The terpy ligands point to the exterior of the chains, distances between neighbored ligands indicate π···π stacking. Magnetic investigations show paramagnetic behavior (µeff = 5.92 µB/Mn2+ at room temperature). Field‐dependent magnetic susceptibility measurements at different temperatures evidence a significant magnetocaloric effect of –ΔS = 20.54 J kg–1 K–1 at T = 2 K for a magnetic field change of ΔB = 9 T. The compound exhibits blue luminescence, and a detailed analysis allowed assignment of the emission and excitation bands to the different constituents of the compound.

Metallic spinel-type CuCo$_{2}$S$_{4}$ nanoparticles were deposited on nanocrystalline TiO$_{2}$ (P25®), forming heterostructure nanocomposites. The nanocomposites were characterized in detail by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), nitrogen sorption (BET) and UV/Vis spectroscopy. Variation of the CuCo$_{2}$S$_{4}$:TiO$_{2}$ ratio to an optimum value generated a catalyst which shows a very high photocatalytic H$_{2}$ production rate at neutral pH of 32.3 µmol/h (0.72 mLh$^{–1}$), which is much larger than for pure TiO$_{2}$ (traces of H$_{2}$). The catalyst exhibits an extraordinary long-term stability and after 70 h irradiation time about 2 mmol H$_{2}$ were generated. An increased light absorption and an efficient charge separation for the sample with the optimal CuCo$_{2}$S$_{4}$:TiO$_{2}$ ratio is most probably responsible for the high catalytic activity.

Metallic spinel‐type CuCo 2 S 4 nanoparticles were deposited on nanocrystalline TiO 2 (P25®), forming heterostructure nanocomposites. The nanocomposites were characterized in detail by X‐ray powder diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM), nitrogen sorption (BET) and UV/Vis spectroscopy. Variation of the CuCo 2 S 4 :TiO 2 ratio to an optimum value generated a catalyst which shows a very high photocatalytic H 2 production rate at neutral pH of 32.3 µmol/h (0.72 mL h –1 ), which is much larger than for pure TiO 2 (traces of H 2 ). The catalyst exhibits an extraordinary long‐term stability and after 70 h irradiation time about 2 mmol H 2 were generated. An increased light absorption and an efficient charge separation for the sample with the optimal CuCo 2 S 4 :TiO 2 ratio is most probably responsible for the high catalytic activity.

The occurrence of a unique 3D nanoscale network in Ni–Cr–S, treatedviaspark-plasma sintering, was discovered with a variety ofex situandin situTEM and XRD techniques.