Search Results (666)

The development of efficient spinel oxide catalysts for low-temperature oxidation of volatile organic compounds (VOCs) remains an important research objective. In this work, Ru was doped into a CoMn₂O₄ spinel to enhance its catalytic activity toward toluene oxidation and the underlying promotion mechanism of Ru doping was systematically investigated. The resulting Ru-CoMn₂O₄ catalyst showed remarkable performance, with T₉₀ reaching approximately 224 °C at a WHSV of 60,000 cm³ g⁻¹ h⁻¹ and nearly 100% CO₂ selectivity above 200 °C. Mechanism studies revealed that the reaction followed both Mars–van Krevelen (MvK) and Eley–Rideal (E–R) pathways. The reaction rates were strongly influenced by the oxidizing capacity of the catalyst, the abundance of highly valent surface species (namely Co³⁺, Mn⁴⁺, and Ru⁴⁺), adsorbed toluene, lattice oxygen, gaseous toluene, and adsorbed oxygen. With Ru doping, new Ru–O–Mn and Ru–O–Co chains formed in the CoMn₂O₄ spinel structure, leading to a moderate enhancement in oxidizing ability and a moderate increase in the concentration of highly valent surface species, adsorbed toluene, and lattice oxygen. Although a slight reduction in adsorbed oxygen was observed, Ru doping significantly boosted the overall toluene oxidation activity of CoMn₂O₄. In summary, Ru-CoMn₂O₄ represented a promising catalyst for the efficient oxidation of VOCs. Full article

A series of silica-supported, nitrogen-doped carbon-encapsulated cobalt–nickel alloy catalysts (Co_xNi_y@NC/SiO₂) was successfully synthesized and systematically evaluated for the liquid-phase hydrogenation of 1-nitronaphthalene to 1-naphthylamine. Physicochemical characterization confirmed that the incorporation of nickel promotes the formation of Co–Ni alloys and modulates the electronic structure of the catalysts. The catalytic performance was found to be highly sensitive to the Co/Ni ratio, with Co₂Ni₁@NC/SiO₂ exhibiting the most outstanding activity. Under optimized reaction conditions (90 °C, 0.6 MPa H₂, 5.5 h), both the conversion of 1-nitronaphthalene and the selectivity toward 1-naphthylamine reached approximately 99%. The catalyst also demonstrated excellent stability and recyclability, attributed to the protective nitrogen-doped carbon shell and the synergistic interaction between the Co–Ni alloy and M–N_x active sites. This work provides a new strategy for designing efficient and robust non-noble-metal catalysts for hydrogenation reactions. Full article

The electrochemical reduction of CO₂ to ethanol represents a sustainable alternative to recycle CO₂ into a value-added product, yet achieving high selectivity and efficiency remains a challenge. This work explores Cu-based catalysts supported on SiO₂ and ZrO₂, with and without ZnO doping, for ethanol production in a continuous flow-cell system. Gas diffusion electrodes are fabricated using commercial catalysts with varying Cu loadings (5–10%) and ZnO contents (2–3.5%). Comprehensive characterization by XPS confirms the presence of Cu²⁺ and Zn²⁺ species, while SEM reveals that ZnO incorporation improves surface uniformity and aggregate distribution compared to undoped samples. Electrochemical tests demonstrate that 10% Cu on SiO₂ achieves a Faradaic efficiency of 96% for ethanol at −3 mA cm⁻², outperforming both doped catalysts and previously reported materials. However, efficiency declines at higher current densities, indicating a trade-off between selectivity and productivity. ZnO doping enhances C₂⁺ product formation but does not surpass the undoped catalyst in ethanol selectivity. These results underline the importance of catalyst composition, support interactions, and operating conditions, and point to further optimization of electrode architecture and cell configuration to sustain high ethanol yields under industrially relevant conditions. Full article

A cobalt-containing zeolitic imidazolate framework (ZIF-67) was carbonized by different routes to composite materials (cZIFs) composed of metallic Co, Co₃O₄, and N-doped carbonaceous phase. The effect of the carbonization procedure on the water pollutant removal properties of cZIFs was studied. Higher temperature and prolonged thermal treatment resulted in more uniform particle size distribution (as determined by nanoparticle tracking analysis, NTA) and surface charge lowering (as determined by zeta potential measurements). Surface-governed environmental applications of prepared cZIFs were tested using physical (adsorption) and electrochemical methods for dye degradation. Targeted dyes were methylene blue (MB) and methyl orange (MO), chosen as model compounds to establish the specificity of selected remediation procedures. Electrodegradation was initiated via an intermediate reactive oxygen species formed during oxygen reduction reaction (ORR) on cZIFs serving as electrocatalysts. The adsorption test showed relatively uniform adsorption sites at the surface of cZIFs, reaching a removal of over 70 mg/g for both dyes while governed by pseudo-first-order kinetics favored by higher mesoporosity. In the electro-assisted degradation process, cZIF samples demonstrated impressive efficiency, achieving almost complete degradation of MB and MO within 4.5 h. Detailed analysis of energy consumption in the degradation process enabled the calculation of the current conversion efficiency index and the amount of charge associated with O₂^•−/^•OH generation, normalized by the quantity of removed dye, for tested materials. Here, the proposed method will assist similar research studies on the removal of organic water pollutants to discriminate among electrode materials and procedures based on energy efficiency. Full article

This study demonstrates the complete transformation of almond shell waste into a high-performance carbon material for carbon paste electrode (CPE) fabrication. The biocarbon was synthesized via carbonization at 800 °C and subsequently activated with CO₂, resulting in a semicrystalline structure rich in carbonyl groups—consistent with its lignocellulosic origin (34.25% cellulose, 13.48% hemicellulose, 48.03% lignin). Carbonization increased the total pore volume of carbonized almond (CAR_ALD) by nearly 13-fold and the specific surface area by over two orders of magnitude compared to raw almond (RAW_ALD), while CO₂ activation further enhanced activated almond’s (ACT_ALD) surface area (~19%) and pore volume (~35%). To improve electrochemical performance, Bi₂O₃ doped with Sm was applied as a surface modifier. Comprehensive characterization (N₂ physisorption X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopic Analysis (FTIR), X-Ray Photoelectron Spectroscopic Analysis (XPS), Thermogravimetric and Differential Thermal Analysis (TG-DTA), Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS)) confirmed the material’s structural integrity, graphitic features, and successful modifier incorporation. Electrochemical testing revealed the highest current response (48 µA) for the CPE fabricated from CAR_ALD/Bi₂O₃-Sm, indicating superior electrocatalytic activity and reduced charge transfer resistance. Notably, this is the first report of a fully functional CPE working electrode fabricated entirely from waste material. Full article

Thin-film organic solar cells (TFOSCs) are gaining momentum as next-generation photovoltaic technologies due to their lightweight nature, mechanical flexibility, and low cost-effective fabrication. In this pioneering study, we report for the first time the incorporation of cobalt-doped zinc sulfide $(\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o})$ nanoparticles (NPs) into a poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) bulk-heterojunction photoactive layer. $\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o}$ NPs were successfully synthesized via a wet chemical method and integrated at varying concentrations (1%wt, 3%wt, and 5%wt) to systematically investigate their influence on device performance. The optimal doping concentration of 3%wt yielded a remarkable power conversion efficiency (PCE) of 4.76%, representing a 102% enhancement over the pristine reference device (2.35%) under ambient laboratory conditions. The observed positive trend is attributed to the localized surface plasmon resonance (LSPR) effect and near-field optical enhancement induced by the presence of ZnS/Co NPs in the active layer, thereby increasing light-harvesting capability and exciton dissociation. Comprehensive morphological and optical characterizations using high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy (HRTEM), and spectroscopic techniques confirmed uniform nanoparticle dispersion, nanoscale crystallinity, and effective light absorption. These findings highlight the functional role of $\mathrm{Z}\mathrm{n}\mathrm{S}/\mathrm{C}\mathrm{o}$ NPs as dopants in enhancing TFOSC performance, providing valuable insights into optimizing nanoparticle concentration. This work offers a scalable and impactful strategy for advancing high-efficiency, flexible, and wearable organic photovoltaic devices. Full article

The methanol oxidation reaction was investigated on Co- and/or Ag-based γ-Al₂O₃ catalysts, which were prepared by different methods (WI: wet impregnation and SI: spray impregnation) and further doped with noble metals (Pd, Pt). During the present study, three different reaction pathways were revealed. The complete oxidation of methanol to CO₂ and H₂O was achieved on Pd-doped catalysts prepared by the spray impregnation method (Pd-Co/Al-SI and Pd-Ag/Al-SI), while partial oxidation to intermediates such as formaldehyde was observed for Ag/alumina catalysts. The dehydration reaction of methanol to dimethyl ether was carried out on Co/alumina, Ag-Co/alumina, and Pt-Co/alumina catalysts. The improved reducibility of the 5Co/Al-SI catalyst with the incorporation of Pd, combined with the easier surface oxygen desorption, resulted in higher catalytic activity compared to the Pt-doped catalyst. On the other hand, the incorporation of Pd into Ag/Al-SI enhanced the well-dispersed Ag₂O species, mainly affecting the structural properties of the catalyst, thus resulting in partial oxidation of methanol. The 0.5 wt.% Pd-5 wt.% Co/γ-Al₂O₃ catalyst, prepared by the spray impregnation method, exhibited the highest methanol oxidation efficiency (T₅₀: 43 °C) and was further evaluated in the presence of H₂O and CO in the feed for several hours on stream and at reaction temperature of 230 °C. The presence of impurities initially reduced the catalyst’s activity from 100% methanol conversion (in the absence of H₂O and CO in the feed) to 80%; however, over time complete methanol oxidation was regained (achieving again 100% methanol conversion after 12 h on stream). Characterization of the used catalyst (after the stability experiment) revealed that in addition to the Co₃O₄ phase, initially formed in the fresh, as-prepared catalyst, some Co₃O₄ species were reduced to CoO under the reaction conditions, suggesting that the active phase of the 0.5Pd-5Co/Al-SI catalyst for the methanol oxidation reaction in the presence of the impurities (such as H₂O and CO) is probably a mixture of Co₃O₄ and CoO phases. Full article

Layered transition-metal oxides are among the most promising sodium-ion battery cathodes owing to their high specific capacities and structurally tunable frameworks. However, the prototypical P2-Na_0.67Ni_0.33Mn_0.67O₂ (NM) undergoes an irreversible P2 → O2 phase transition at high voltages, accompanied by severe lattice strain and capacity fade, which hinders practical deployment. Here, we propose a cooperative regulation strategy that couples Zn/Al co-doping with Na enrichment, and successfully synthesize P2-Na_0.80Ni_0.14Zn_0.14Mn_0.58Al_0.14O₂ (NMZA-N14). The optimized NMZA-N14 delivers an initial discharge capacity of 125 mAh g⁻¹ at 0.1C and demonstrates exceptional cycling and rate performance, retaining 98.6% of its capacity after 100 cycles at 0.2C and 93.6% after 200 cycles at 1C. Kinetic analyses indicate a higher Na⁺ diffusion coefficient and a lower charge-transfer resistance in NMZA-N14, evidencing substantially accelerated ion transport. In situ X-ray diffraction further reveals a reversible P2 → OP4 phase transition in the high-voltage regime with a unit-cell volume change of only ~2.27%, thereby avoiding the irreversible structural degradation observed in NM. This synergistic modulation markedly enhances structural stability and electrochemical kinetics, providing a viable pathway for the rational design of high-performance sodium-ion battery cathodes. Full article

This study reports the design of N- and S-doped ordered mesoporous carbon hollow spheres (OMCHS) as metal-free electrocatalysts for the oxygen reduction reaction (ORR) in alkaline media. Three electrocatalysts were synthesized using molecular precursors: (i) 2-thiophenemethanol (S-OMCHS), (ii) 2-pyridinecarboxaldehyde/2-thiophenemethanol (N1-S-OMCHS), and (iii) pyrrole/2-thiophenemethanol (N2-S-OMCHS). Among them, S-OMCHS exhibited the best activity (E_onset = 0.88 V, E_½ = 0.81 V, n ≈ 3.95), surpassing both co-doped analogs. After conducting an accelerated degradation test (ADT), S-OMCHS and N1-S-OMCHS showed improved catalytic behavior and outstanding long-term stability. Surface analysis confirmed that performance evolution correlates with heteroatom reorganization: S-OMCHS retained and regenerated thiophene-S and C=O/quinone species, while N1-S-OMCHS converted N-quaternary into N-pyridinic/pyrrolic, both enhancing O₂ adsorption and *OOH reduction through synergistic spin–charge coupling. Conversely, oxidation of N and loss of thiophene-S in N2-S-OMCHS led to partial deactivation. These results establish a direct link between surface chemistry evolution and electrocatalytic durability, demonstrating that controlled heteroatom doping stabilizes active sites and sustains the four-electron ORR pathway. The approach provides a rational design framework for next-generation, metal-free carbon electrocatalysts in alkaline fuel cells and energy conversion technologies. Full article

The development of highly active, thermally stable, and low-CO-selective catalysts is critical for practical methanol steam reforming (MSR) to produce high-purity hydrogen for fuel cell applications. In this work, a series of Mn–Cu/Al₂O_x catalysts with varying Mn/Cu/Al molar ratios were synthesized via co-precipitation and systematically investigated to establish the relationship between composition, structure, and catalytic performance. XRD analysis revealed the formation of spinel-type CuAl₂O₄ and MnAl₂O₄ phases, with Mn preferentially occupying octahedral B-sites to form MnAl₂O₄, thereby inducing lattice distortion and inhibiting grain growth. SEM and TEM–EDS mapping confirmed uniform elemental distribution and a porous nanoscale morphology, while H₂-TPR results suggested that increasing the Mn/Cu ratio strengthens Mn–Cu interactions, shifts Cu²⁺ reduction to higher temperatures, and enhances Cu dispersion (up to 26.11 m²/g). XPS analysis indicated that Mn doping enriches Mn³⁺ species and facilitates oxygen vacancy formation, which promotes water–gas shift (WGS) activity and suppresses CO formation. Catalytic testing (240–300 °C) showed that Mn₂Cu₂Al₄O_x achieved the highest methanol conversion while maintaining low CO selectivity; in contrast, reducing the Mn/Cu ratio increased CO selectivity, detrimental to hydrogen purification. Stability tests under continuous steam exposure for 24 h demonstrated minimal activity loss (~2%) and negligible increase in CO selectivity (<1%), confirming excellent hydrothermal stability. The results indicate that tailoring the Mn/Cu ratio optimizes the balance between redox properties and metallic Cu dispersion, offering a promising route to design low-CO, durable catalysts for on-site hydrogen generation via MSR. Full article

The chemical diffusion coefficients of oxygen ($D^{\delta }$) for the oxides BaFe_0.9Ce_0.1O_3−δ (BFC10), BaFe_0.9Y_0.1O_3−δ (BFY10), and BaFe_0.8Ce_0.1Y_0.1O_3−δ (BFCY1010) were determined by the oxygen pressure relaxation method in the T = 600–800 °C and pO₂ = 0.1–3.5 kPa ranges. The oxygen diffusion coefficients at 700 °C were found to be 1.80·10⁻⁵, 3.92·10⁻⁵, and 1.85·10⁻⁵ cm²/s for BFC10, BFY10, and BFCY1010, respectively. It was established that the volume oxygen diffusion increases in the order $D^{\delta }$(BFY10) > $D^{\delta }$(BFCY1010) > $D^{\delta }$(BFC10), which correlates with the data on oxygen non-stoichiometry (δ), and is associated with the oxygen vacancy content in oxides. The values of effective activation energies were determined: 1.21 ± 0.04, 1.31 ± 0.10, and 1.18 ± 0.09 eV for BFC10, BFY10, and BFCY1010, respectively. A comparative analysis of oxygen transport highlights the potential of co-doped BaFe_0.8Ce_0.1Y_0.1O_3−δ as a promising cobalt-free cathode material with triple (oxygen, proton, electron) conductivity. Full article

Copper (Cu) doping is recognized as an effective strategy to enhance the electrochemical properties of LiNi_1−x−yCo_xMn_yO₂ (NCM) cathode materials. However, the influence of Cu²⁺ doping on particle size and grain boundary fusion remains insufficiently explored. A simple microwave-assisted solution combustion synthesis method was used to introduce Cu²⁺ into LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523), aiming to regulate particle size and grain boundary fusion. The results demonstrate that increasing the Cu²⁺ doping content promotes particle growth, while an appropriate doping level reduces the degree of grain boundary fusion and cation mixing. Benefiting from these structural improvements, the optimized LiNi_0.5Co_0.2Mn_0.29Cu_0.01O₂ (Cu–1) cathode exhibits significantly enhanced electrochemical performance, delivering a discharge capacity of 128.6 mAh g⁻¹ after 100 cycles at 0.2 C, which is 32 mAh g⁻¹ higher than value of the undoped sample (96.6 mAh g⁻¹). These findings underscore that tailored Cu²⁺ doping can effectively optimize the microstructure of NCM523, leading to superior cycling stability, and provide new insights into the design of high-performance NCM cathodes. Full article

Background: Minimally invasive hyperthermia and regenerative therapies require materials that deliver precise, localized heat without compromising biocompatibility. Most conventional polymers are thermally insulating and challenging to control in vivo, motivating this review. Objectives: We aimed to (i) examine the use of thermally enhanced biopolymers in hyperthermia-based therapies, (ii) appraise evidence from clinical and preclinical studies, (iii) identify and classify principal applications in regenerative medicine. Methods: A PRISMA-guided systematic review (2020–2025) with predefined inclusion/exclusion criteria was conducted and complemented by a bibliometric analysis using VOSviewer for mapping and visualization. Results: Modifying biopolymers—via functionalization with photothermal or magnetic nanoagents (Au; Fe₂O₃/Fe₃O₄/CoFe₂O₄; CuS; Ag; MXenes, e.g., Nb₂C), crosslinking strategies, and hybrid formulations—significantly increased thermal conductivity, enabling localized hyperthermia and controlled drug release. In vitro and in vivo studies showed that europium-doped iron oxide nanoparticles embedded in chitosan generated heat efficiently while sparing healthy tissues, underscoring the need to balance biocompatibility and thermal performance. Hydrogel systems enriched with carbon nanomaterials (graphene, carbon nanotubes) and matrices such as GelMA, PNIPAM, hyaluronic acid, and PLA/PLGA demonstrated tissue compatibility and effective thermal behavior; graphene was compatible with neural tissue without inducing inflammation. Conclusions: Thermally conductive biopolymers show growing potential for oncology and regenerative medicine. The evidence supports further academic and interdisciplinary research to optimize safety, performance, and translational pathways. Full article

Thermal barrier coatings (TBCs) are critical for protecting hot-section components in gas turbines and aero-engines. Traditional yttria-stabilized zirconia (YSZ) coatings are prone to phase transformation and sintering-induced failure at elevated temperatures. This study fabricated CeScYSZ (4 mol% CeO₂ and 6 mol% Sc₂O₃ co-doped YSZ)/NiCrAlY TBCs using atmospheric plasma spraying (APS). A five-factor, four-level orthogonal experimental design was employed to optimize spraying parameters, investigating the influence of powder feed rate, spray distance, current, hydrogen flow rate and primary gas flow rate on the coating’s microstructure and mechanical properties. The resistance to calcium–magnesium–alumino–silicate (CMAS) corrosion was compared between CeScYSZ and YSZ coatings. The results indicate that the optimal parameters are a spray distance of 100 mm, current of 500 A, argon flow rate of 30 L/min, hydrogen flow rate of 6 L/min, and powder feed rate of 45 g/min. Coatings produced under these conditions exhibited moderate porosity and excellent bonding strength. After exposure to CMAS corrosion at 1300 °C for 2 h, the CeScYSZ coating demonstrated significantly superior corrosion resistance compared to YSZ. This enhancement is attributed to the formation of a CaZrO₃ physical barrier and the synergistic effect of Ce and Sc in suppressing deleterious phase transformations. This study provides an experimental basis for the preparation and application of high-performance TBCs. Full article

Acetone necessitates reliable detection for the sake of both industrial and environmental safety. Metal oxides are widely used as functional materials for the development of gas sensors because techniques like nanostructure modification, doping, and solid solution formation can enhance their sensitivity and selectivity by tuning structural and electronic properties. This study developed PrFeTiO₅ nanostructures, synthesized via the solid-state reaction for acetone sensing. The sensor demonstrated a high response to acetone at an operating temperature of 400 °C, with a low influence of humidity, displaying outstanding selectivity towards acetaldehyde, NH₃, H₂, CO, and CO₂, making it suitable across various applications. Full article