Abundant Mesoporous Structure Research Articles

RGO@MoS2 as the host-separator modifier with efficient polysulfides trapping and fast Li+ diffusion for lithium-sulfur batteries

Lithium sulfur battery is widely regarded as the most promising next generation energy storage systems because of its high specific energy (2600 Wh kg−1). However，its commercial application is still limited by numerous challenges, including the insulation of charging/discharging products sulfur and Li2S2/Li2S, as well as the "shuttle effect" triggered by the soluble polysulfides. Herein, we report that a functional separator modified by a rGO@MOS2 composites comprising ultrathin MoS2 nanosheets in-situ growth on the surface of reduced graphene oxide (rGO). This composite boasts -an abundant mesoporous structure and large specific surface area can effectively adsorb lithium polysulfides (LiPSs). Additionally, the introduction of high conductive rGO and ultrathin MoS2 nanosheets with rich edge active sites can accelerate the catalytic transformation reaction from LiPSs to Li2S2/Li2S, thus inhibiting the "shuttle effect". In comparison to Li-S batteries without rGO@MoS2 composites, batteries equipped with the functional separator exhibit an impressive initial discharge capacity of 1125.4 mAh g−1 at 1 C, and retain at 910.4 mAh g−1 after 200 cycles, with a low capacity decay rate of 0.09 % per cycle, indicating excellent cyclic stability. Moreover, the areal capacity of the electrode with high sulfur loading mass of 4.1 mg cm−2 is 4.1 mAh cm−2, approaching the practical application standard at a current density of 0.1 C.

Oxygen vacancy-induced nonradical degradation of nitroso-containing organics in Fe3O4@N[sbnd]C electro-Fenton reaction at a wide pH range

In this work, Fe3O4-anchored nitrogen-doped carbon catalyst (Fe3O4@N–C) with abundant oxygen vacancies (Vo) and mesoporous structure was successfully synthesized for electro-Fenton (EF) catalytic process. The catalyst demonstrated impressive degradation efficiency towards nitroso-containing organics due to the superior electronic transfer of N–C skeleton and Vo, making it easier for the electron-deficient –NO2 groups to adsorb on the catalyst surface and oxidize rapidly. Typically, the degradation efficiency of p-nitrophenol (PNP) reached 95.6 % in natural pH. Notably, the catalyst exhibited excellent performance over a wide pH range (3 ∼ 11), and has strong anti-interference performance against anions and natural organic matter in water matrix. Mechanism analysis indicated that Vo could promote the formation of highly active electron-rich Fe(II) species, and promote the activation of H2O2 and O2 as additional active sites, thus, a large amount of ·OH and O2·- would be produced and then quickly converted into 1O2. As a result, 1O2 is the main reactive species for PNP degradation in Fe3O4@N–C electro-Fenton reaction. The results will provide insights into the design of high-performance catalysts for the selective oxidation of organic pollutants in wastewater.

S-doped mesoporous graphene modified separator for high performance lithium-sulfur batteries

Due to their low cost, environmental friendliness and high energy density, the lithium-sulfur batteries (LSB) have been regarded as a promising alternative for the next generation of rechargeable battery systems. However, the practical application of LSB is seriously hampered by its short cycle life and high self-charge owing to the apparent shuttle effect of soluble lithium polysulfides. Using MgSO4@MgO composite as both template and dopant, template-guided S-doped mesoporous graphene (SMG) is prepared via the fluidized-bed chemical vapor deposition method. As the polypropylene (PP) modifier, SMG with high specific surface area, abundant mesoporous structures and moderate S doping content offers a wealth of physical and chemical adsorptive sites and reduced interfacial contact resistance, thereby restraining the serious shuttle effects of lithium polysulfides. Consequently, the LSB configured with mesoporous graphene (MG) as S host material and SMG as a separator modifier exhibits an enhanced electrochemical performance with a high average capacity of 955.64 mA h g−1 at 1C and a small capacity decay rate of 0.109% per cycle. Additionally, the density functional theory (DFT) calculation models have been rationally constructed and demonstrated that the doped S atoms in SMG possess higher binding energy to lithium polysulfides than that in MG, indicating that the SMG/PP separator can effectively capture soluble lithium polysulfides via chemical binding forces. This work would provide valuable insight into developing a versatile carbon-based separator modifier for LSB.

Efficient degradation of m-cresol by MnO-doped red mud catalyst activating peroxymonosulfate process: Performance and mechanism

M-cresol, one of phenolics, is highly toxic, refractory, and threatens human health and ecological safety. The study on the efficient m-cresol degradation technologies is crucial and helpful to restrain its discharge into water body. A composite of MnO-doped red mud (RM) to activate peroxymonosulfate (PMS) for the m-cresol degradation was fabricated and employed, favorable to the recycling and utilization of RM. Considering the catalytic activity and cost, 0.1 M/RM@G exhibited an excellent degradation capacity attributing to strong Fe3O4 and MnO synergy and was considered as the best catalyst among the investigative catalysts. 100 % of m-cresol and 71.4 % of COD could be degraded within 90 min under 2 g/L catalyst, 10 mM of PMS, 3-8 of initial pH and 50 mg/L m-cresol in the 0.1 M/RM@G/PMS system. The reaction rate constant (0.045 min−1) of 0.1 M/RM@G was much larger than RM@G (0.012 min−1), ARM (0.0048 min−1) and WRM (0.0028 min−1). Main Mn and Fe active components and abundant mesoporous structures on the catalyst surface could efficiently drove electron transfers, and further accelerated the redox cycles of Mn(III)Mn(II) and Fe(III)Fe(II) for activating PMS. 1O2 played a crucial role in degrading m-cresol. Based on the experiment data, the generation mechanism of radicals and the possible pathways of m-cresol degradation were proposed in the 0.1 M/RM@G/PMS system. This finding provides a new way for the synthesis of the efficient catalyst with RM and optimal operating strategies for the treatment of m-cresol wastewater.

La‐Doped Mg‐Al Composite Oxides: Efficient Catalysts for the synthesis of Diethyl Carbonate via Transesterification of Ethylene Carbonate with Ethanol

AbstractSeries of La‐doped Mg−Al composite oxides were prepared by co‐precipitation method and used as catalysts for the synthesis of diethyl carbonate (DEC) via transesterification of ethylene carbonate (EC) with ethanol (EtOH). SEM, XRD, FT‐IR and XPS results confirmed that the introduction of La enhanced the interaction with MgO. The 8 mol % La‐doped Mg−Al composite oxide (calcined catalyst named HTC‐0.8 La) produced strong interactions and improved lattice oxygen content (27.84 %). Based on the N2 adsorption‐desorption and CO2‐TPD results, the HTC‐0.8 La catalysts possessed abundant multistage mesoporous structure, high strong base density and strength (0.941 mmol ⋅ g−1). Therefore, the HTC‐0.8La catalyst exhibited high catalytic activity with 58.5 % yield of DEC and 94.7 % selectivity to DEC (EC: EtOH molar ratio=1 : 6, reaction time=1.5 h, reaction temperature=150 °C and catalyst amount=3.2 wt %). Based on the correlation between catalytic activity and alkalinity, the yield of DEC was positively and linearly related to the strong alkali density of the catalyst. After five replicate experiments, the DEC yield after recovery and roasting reached 54.1 %, indicating that HTC‐0.8La is a renewable heterogeneous catalyst.

B, S co-doped mesoporous carbon as an efficient catalyst for H2O2 electrosynthesis in natural seawater

The small-scale electrochemical synthesis of hydrogen peroxide (H2O2) in marine environments is of great significance for environmental wastewater treatment, and the design of electrocatalysts for complicated marine conditions is the key for this technology. Although B-doped carbon materials have been demonstrated to be resistant to Cl− poisoning, the deposition of Ca2+ on the surface of catalyst in seawater and the sluggish reaction kinetics of non-metallic catalysts remain to be solved. Herein, B, S co-doped mesoporous carbon materials were synthesized by a simple NaCl template method. The H2O2 yield of the as-prepared sample was up to 3.66 mol/(gcat h) with a Faradaic Efficiency (FE) of 97.98 % at 100 mA/cm2 in natural seawater, and achieved 100 % inactivation of bacteria and Chlorella within 5 min at a low current density. Based on the structural characterization and electrochemical results, the S-containing structure on the carbon matrix suppresses Ca2+ deposition due to its excellent proton adsorption activity. Furthermore, the electron transfer process between the reactant and BC3 was enhanced by the abundant mesoporous structure, so as to optimize the sluggish oxygen reduction reaction (ORR) kinetics on BC3. This work offers a strategy for inactivation of marine microorganisms and the degradation of organic pollutants, which promotes the advancement of marine wastewater treatment technology, and also provides reference for the design of metal free catalysts used in marine environments.

Rational Design of Nanosheet Array-Like Layered-Double-Hydroxide-Derived NiCo2O4 In Situ Grown on Reduced-Graphene-Oxide-Coated Nickel Foam for High-Performance Solid-State Supercapacitors.

The investigation of high-performance supercapacitors is essential for accelerating the development of energy storage devices. In this work, a 3D hierarchical nanosheet array-like nickel cobaltite/reduced graphene oxide/nickel foam composite (NiCo2O4/rGO/NF) was assembled via an aqueous coprecipitation-hydrothermal strategy assisted by citric acid. Benefiting from a NiCo layered-double-hydroxide precursor with an atomic-level lattice confinement effect of metal ions and effective hybridization with rGO, the NiCo2O4/rGO/NF composite is featured as thin NiCo2O4 nanosheets (∼113.6 nm × 11.2 nm) composed of NiCo2O4 nanoparticles (∼10.9 nm) vertically staggered on the surface of a rGO-modified NF skeleton, leading to high surface area, abundant mesoporous structure, and active site exposure. The as-obtained NiCo2O4/rGO/NF was directly used as a binder-free integrated electrode for supercapacitors, achieving an excellent specific capacitance of 2863.4 F g-1 (1503.3 C g-1) at 1 A g-1, a superior rate performance of 2335.2 F g-1 at 20 A g-1, and a stability retention of 91.7% after 5000 cycles. More impressively, a solid-state asymmetric supercapacitor assembled by the present NiCo2O4/rGO/NF integrated electrode as the positive electrode and commercial activated carbon as the negative electrode achieved a high energy density of 69.2 Wh kg-1 at a power density of 800 W kg-1, and the energy density at a peak power density of 20004 W kg-1 still remained at 48.9 Wh kg-1, also showing a good cycling stability of 87.2% retention over 10000 cycles. The present facile synthesis strategy of the as-obtained NiCo2O4/rGO/NF nanosheet array composite can be used for the design and construction of many other transition-metal oxide/graphene/NF composite materials with excellent structural stability and performance in energy storage and other related areas.

Enzymolytic lignin derived Fe–N codoped porous carbon materials as catalysts for oxygen reduction reactions

Numerous active sites and hierarchical pore structures are important for improving catalytic performance for the oxygen reduction reaction (ORR). In this work, a series of iron-nitrogen-doped porous carbon materials (Fe–N–C) with ORR catalytic activity were prepared by a one-step pyrolysis method using enzymolytic lignin as the raw material, soy protein isolate and iron chloride as dopants. The results showed that the samples with the best performance have abundant Fe-Nx active sites and mesoporous structures. At the same time, the electrocatalytic results indicate that the half-wave potential of catalyst was 0.84 V, which reached 96.55% of commercial Pt/C catalysts (E1/2 = 0.86 V), it still preserves an initial current density of 92%, after 10,000 s of circulation, which is much better than Pt/C (86%). Due to the low cost, high activity and stable ORR property, the prepared non-precious metal electrocatalyst will play an important role in the applications of fuel cells.

Cobalt nanoparticles supported on nitrogen-doped carbon nanotubes for the efficient oxygen reduction reaction in Mg-air battery

Fabricating the non-precious-metal catalyst with desirable catalytic performance towards oxygen reduction reaction (ORR) is essential for Mg-air battery that adopts neutral brine electrolyte. However, the classic metal-nitrogen-carbon materials with strong ORR catalytic activity in alkaline solution usually display inferior performance than platinum-based catalysts in neutral environment. Herein, we construct a hybrid catalyst composed of cobalt nanoparticles and nitrogen-doped carbon nanotubes, based on pyrolyzing the mixture of melamine, pyrazole, hexadecyl trimethyl ammonium bromide, and 2-methylimidazole chelated with Co2+ and Zn2+ ions. This catalyst possesses abundant ORR catalytic active sites and mesoporous structure with large pore volume, which can result in the superior performance of Mg-air battery than that using Pt/C catalyst. Furthermore, its ORR catalytic mechanism is unraveled according to microstructure characterization and electrochemical response.

Microwave‐Assisted Rapid Synthesis of MOF‐Based Single‐Atom Ni Catalyst for CO2 Electroreduction at Ampere‐Level Current

AbstractCarbon‐based single‐atom catalysts (SACs) have attracted tremendous interest in heterogeneous catalysis. However, the common electric heating techniques to produce carbon‐based SACs usually suffer from prolonged heating time and tedious operations. Herein, a general and facile microwave‐assisted rapid pyrolysis method is developed to afford carbon‐based SACs within 3 min without inert gas protection. The obtained carbon‐based SACs present high porosity and comparable carbonization degree to those obtained by electric heating techniques. Specifically, the single‐atom Ni implanted N‐doped carbon (Ni1−N−C) derived from a Ni‐doped metal–organic framework (Ni‐ZIF‐8) exhibits remarkable CO Faradaic efficiency (96 %) with a substantial CO partial current density (jCO) up to 1.06 A/cm2 in CO2 electroreduction, far superior to the counterpart obtained by traditional pyrolysis with electric heating. Mechanism investigations reveal that the resulting Ni1−N−C presents abundant defective sites and mesoporous structure, greatly facilitating CO2 adsorption and mass transfer. This work establishes a versatile approach to rapid and large‐scale synthesis of SACs as well as other carbon‐based materials for efficient catalysis.

Microwave-Assisted Rapid Synthesis of MOF-Based Single-Atom Ni Catalyst for CO2 Electroreduction at Ampere-Level Current.

Carbon-based single-atom catalysts (SACs) have attracted tremendous interest in heterogeneous catalysis. However, the common electric heating techniques to produce carbon-based SACs usually suffer from prolonged heating time and tedious operations. Herein, a general and facile microwave-assisted rapid pyrolysis method is developed to afford carbon-based SACs within 3 min without inert gas protection. The obtained carbon-based SACs present high porosity and comparable carbonization degree to those obtained by electric heating techniques. Specifically, the single-atom Ni implanted N-doped carbon (Ni1 -N-C) derived from a Ni-doped metal-organic framework (Ni-ZIF-8) exhibits remarkable CO Faradaic efficiency (96 %) with a substantial CO partial current density (jCO ) up to 1.06 A/cm2 in CO2 electroreduction, far superior to the counterpart obtained by traditional pyrolysis with electric heating. Mechanism investigations reveal that the resulting Ni1 -N-C presents abundant defective sites and mesoporous structure, greatly facilitating CO2 adsorption and mass transfer. This work establishes a versatile approach to rapid and large-scale synthesis of SACs as well as other carbon-based materials for efficient catalysis.

Reusable porous chromium- zinc oxide nano-sheets for efficient detoxification of xenobiotics through integrated advanced oxidation water clean-up process

An integrated approach of acoustic, ultraviolet, and sunlight-driven Advanced Oxidation Process (AOP) is an excellent choice in the quest for a water-cleaning process. This research delves into the realization of chromium-doped zinc oxide (Cr/ZnO) nanopores as a low energy, eco-friendly, efficient, and exhibiting stable photocatalysis for the AOP process. Ultrasonic-aided co-precipitation technique was used for the synthesis of porous Cr-ZnO nanostructures. X-ray diffraction patterns and FTIR spectra of the synthesized samples revealed that chromium ions were effectively intruded into the ZnO lattice. Tauc's equation and Kubella Munk plots have explored that the incorporation of Cr dopants in ZnO reduces the optical band energy. The formation of porous structures was evinced in SEM, TEM, HRTEM, and BET studies. The presence of abundant mesoporous structures was confirmed by the adsorption/desorption isotherms of type IV hysteresis. The antimicrobial efficacy of Cr-ZnO against aqueous bacteria, Staphylococcus aureus, and Escherichia coli was comparatively as effective as the control. The integrated AOP approach enhances the electron trapping characteristics of nanoporous Cr-ZnO catalysts to generate self-sustained in-situ reactive oxygen species on the aqueous matrix. In the current research, methylene orange and nitro phenol were detoxified up to 99 % and 98.2 %, and their half-life degradation rate constant was 22 min and 26 min, respectively. The total organic contaminants (TOC) test on the resultant treated water has confirmed the effective detoxification of xenobiotic molecules and the possibility of reusing the treated water. The ecotoxicology research using treated water on flora and primary aquatic microfauna has supported the possibility of practical utilization of Cr-ZnO in harmless environmental adaptation in the foreseeable future.

Catalytic co-pyrolysis of waste tea residue and waste plastics to carbon nanomaterials: Catalyst support, reaction temperature and product application

The search for cost-effective, high-performance catalysts is crucial in catalytic co-pyrolysis. Different Fe-Mo@X catalysts (X = Al2O3, MgO) and reaction temperatures (600 ℃, 700 ℃, 800 ℃, 900 ℃) were tested to optimize hydrogen production and carbon quality while also exploring CNTs degradation performance. The results indicate that both catalyst type and operating parameters are highly dependent on the growth of carbon nanotubes and hydrogen. The FeMo@Al2O3 catalyst exhibits superior catalytic activity attributed to its more abundant mesoporous structure and higher specific surface area. Specifically, FeMo@Al2O3 achieved the highest yield of carbon nanotubes (84.42%) at 700 ℃, and attained the maximum hydrogen yield (49.57%) at 900 ℃. However, the CNTs synthesized from FeMo@MgO exhibited fewer defects, higher graphitization degree and purity (Raman and TPO). CNTs/MgO significantly enhanced the degradation efficiency of Clothianidin by virtue of their superior electron transport properties and chemical bonding between MgO and CNTs.

Enzymolytic Lignin-Derived N-S Codoped Porous Carbon Nanocomposites as Electrocatalysts for Oxygen Reduction Reactions.

Currently, the development of nonmetallic oxygen reduction reaction (ORR) catalysts based on heteroatomic-doped carbon materials is receiving increaseing attention in the field of fuel cells. Here, we used enzymolytic lignin (EL), melamine, and thiourea as carbon, nitrogen, and sulfur sources and NH4Cl as an activator to prepare N- and S-codoped lignin-based polyporous carbon (ELC) by one-step pyrolysis. The prepared lignin-derived biocarbon material (ELC-1-900) possessed a high specific surface area (844 m2 g-1), abundant mesoporous structure, and a large pore volume (0.587 cm3 g-1). The XPS results showed that ELC-1-900 was successfully doped with N and S. ELC-1-900 exhibited extremely high activity and stability in alkaline media for the ORR, with a half-wave potential (E1/2 = 0.88 V) and starting potential (Eonset = 0.98 V) superior to those of Pt/C catalysts and most non-noble-metal catalysts reported in recent studies. In addition, ELC-1-900 showed better ORR stability and methanol tolerance in alkaline media than commercial Pt/C catalysts.

Poly(lactic acid) synthesized from non‐food biomass feedstocks with tin‐loaded ZA molecular sieve catalysts by direct melt polycondensation

AbstractThe design and synthesis of catalysts loaded with active components has attracted considerable attention in current research owing to their exceptional catalytic performance. In this study, the focus was on the utilization of tin‐loaded ZA molecular sieves, possessing remarkable adsorption properties, alongside the catalytic activity of tin. These catalysts were successfully prepared and employed for the synthesis of poly(lactic acid) (PLA) from lactic acid derived from non‐food biomass. By modifying the treatment of ZA molecular sieves, the properties of tin‐loaded ZA molecular sieves were adjusted. The resulting catalysts exhibited a high tin capacity ranging from 2.29% to 2.81% and featured abundant mesoporous structures, providing a surface area of up to 341.2 m2 g−1. Regarding the preparation of PLA, our findings demonstrated that ZA‐III‐Sn2+ as a catalyst yielded PLA with a higher weight‐average molecular weight (Mw) up to 2.57 × 104 g mol−1 and a higher yield of 65.3% compared to other catalysts. Moreover, the most optimal catalytic effect was achieved by adding the catalyst in three separate stages. Moreover, the amount of catalyst, reaction temperature and reaction time were found to influence both the molecular weight and yield of PLA. This study not only provides a valuable strategy for the preparation of loaded catalysts for PLA production but also offers new insights into the overall preparation process of PLA. © 2023 Society of Industrial Chemistry.

Electrochemically alternating voltage induction and in-situ preparation of tin-based multiphase structures anode for sodium-ion batteries

Tin-based materials possess a high-capacity as a potential anode for Na-ion batteries (SIBs), but the inferior electric conductivity and sluggish reaction kinetics limit their further development. In this paper, we have successfully constructed multiphase structure SnO2/SnS/SnS2 by combining the electrochemical induction and in-situ hydrothermal method to effectively alleviate these problems. The continuous addition of sulfur source (thioacetamide, TAA) results in the formation of a transition from pure product (SnO2) to double structure (SnO2/SnS), and finally multiphase structure (SnO2/SnS/SnS2). Compared to single or bimetal chalcogenides, the tri-metal chalcogenides have strengthened synergistic effects between diverse components. Additionally, the SnO2/SnS/SnS2 composites exhibit small grain size and abundant mesoporous structure, which aid to shorten the distance of ions transfer and increase surface active sites for Na-ions storage. The SnO2/SnS/SnS2 anode displays optimal diffusion coefficient (1.94 × 10−15 cm2 s−1) and cycling durability, with a recoverable specific discharge ability of 401 mA h g−1 over 100 cycles at 100 mA g−1 and a maintenance overpasses 77 %. These results indicate that the construction of multiphase structures is a prospective way to improve the reaction kinetics of Sn-based materials for SIBs.

Facile and green synthesis of biomass-derived N, O-doped hierarchical porous carbons for high-performance supercapacitor application

The development of superior electrode materials using biomass as sustainable carbon sources is of great significance in promoting the practical application of supercapacitors. Herein, we prepared a N, O co-doped hierarchical porous carbon (GPC-0.9 N) with an ultra-high specific surface area of 2808.65 m2 g−1 and abundant microporous, mesoporous and macroporous structures through the straightforward pre-carbonization method using garlic peels combined with KHCO3/melamine activation. Additionally, the relatively high nitrogen (3.81%) and oxygen content (4.79%) can enhance the wettability of the carbon materials and introduce additional pseudocapacitance. As a result, the electrode material achieved a high specific capacitance of 396.25 F g−1 at 1 A g−1 and outstanding rate capability of 283.13 F g−1 at 25 A g−1 in 6 M KOH electrolyte in a three-electrode system. Meanwhile, the symmetrical supercapacitor based on the GPC-0.9 N electrode material showed a high energy density of 9.07 Wh kg−1 at the power density of 309.2 W kg−1. Furthermore, it exhibited excellent cycling stability, with 92.5% of the capacitance retained after 10000 cycles at 10 A g−1. This research provides insights for the rational design of a green, renewable and eco-friendly biomass-derived porous carbon that can be widely used as supercapacitor electrode materials in the future.

Mediated electron transfer process in α-MnO2 catalyzed Fenton-like reaction for oxytetracycline degradation

In Fenton-like oxidation, the catalyst directly influences the reaction mechanism for the degradation of pollutants from water. Here, a α-MnO2 catalyst (OAm-1) was synthesized via a self-assembly method with the assistance of a surfactant. OAm-1 possessed a large specific surface area of 221 m2/g, abundant mesoporous structures and a large proportion of Mn(III). Further characterization exhibited that OAm-1 had abundant oxygen vacancies and excellent reducibility and conductivity. The adsorption and catalytic ability of OAm-1 were studied in the degradation of oxytetracycline (OTC) via the activation of hydrogen peroxide (H2O2). Through the radical quenching experiments, electron resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) analysis, Mn(III) of OAm-1 was proved to be the active sites for the chemisorption of OTC. Systematic electrochemical experiments and analysis have shown that a process of electron transfer mediated by OAm-1 occurred between the pollutant and H2O2 during a Fenton-like reaction. This work experimentally verifies the electron transfer process dominated nonradical mechanism over α-MnO2, which is helpful for understanding the catalytic mechanism of the Fenton-like oxidation.

Comprehensive investigation on fast pyrolysis of waste Lotus shells to produce valuable products: Pyrolysis characteristics, reaction mechanism and economic analysis

Lotus shells (LS) represent an abundant, underutilized renewable resource with significant potential for producing bio-based fuels and chemicals. Pyrolysis emerges as an effective means to maximize the value derived from LS waste. This study assessed the behavior, kinetics of LS pyrolysis for bioenergy production through thermogravimetric analysis (TGA), model-free and model methods. The product distribution resulting from LS fast pyrolysis and the physicochemical properties of the derived products were comprehensively investigated. A plausible reaction mechanism for LS pyrolysis was proposed, followed by an estimation of the associated costs for bioenergy production through pyrolysis. The activation energy (Eα) for LS calculated through Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman (FR) methods was 197.36 kJ/mol, 193.66 kJ/mol, and 197.16 kJ/mol, respectively. The kinetic reaction model for LS pyrolysis was represented by the equation f(α) = α−26.59(1-α)12.35[-ln(1-α)]−27.26, indicating the dominance of a diffusion model and nucleation mechanism in the LS pyrolysis process. Notably, the fast pyrolysis bio-oil derived from LS mainly comprised phenols (34.73 % at 300 °C), acids (42.33 % at 600 °C), and nitrogenous compounds (27.40 % at 800 °C), and the gaseous products primarily consisted of H2, CH4, CxHy, CO, and CO2. Biochar derived from LS exhibited abundant functional groups and mesoporous structure, and its moderate C/N ratio and low H/C ratio indicated potential for soil remediation. Furthermore, the high heating value (21.55–27.01 MJ/kg) of LS biochar exceeded that of Zhaotong lignite, demonstrating its favorable combustion characteristics. This study lays the theoretical foundation for the efficient treatment and high-value utilization of Lotus shells.

Insights into SnO2 Nanoparticles Supported on Fibrous Mesoporous Silica for CO Catalytic Oxidation

A large surface area dendritic mesoporous silica material (KCC-1) was successfully synthesized and used as a support to confine SnO2 nanoparticles (NPs). Owing to the large specific surface area and abundant mesoporous structure of dendritic KCC-1, the SnO2 NPs were highly dispersed, resulting in significantly improved CO catalytic oxidation activity. The obtained Snx/KCC-1 catalysts (x represents the mass fraction of SnO2 loading) exhibited excellent CO catalytic activity, with the Sn7@KCC-1 catalyst achieving 90% CO conversion at about 175 °C. The SnO2 NPs on the KCC-1 surface in a highly dispersed amorphous form, as well as the excellent interaction between SnO2 NPs and KCC-1, positively contributed to the catalytic removal process of CO on the catalyst surface. The CO catalytic removal pathway was established through a combination of in situ diffuse reflectance infrared transform spectroscopy and density-functional theory calculations, revealing the sequential steps: ① CO → CO32−ads, ② CO32−ads → CO2free+SnOx−1, ③ SnOx−1+O2 → SnOx+1. This study provides valuable insights into the design of high-efficiency non-precious metal catalysts for CO catalytic oxidation catalysts with high efficiency.