Mesoporous Structure Research Articles

Mesoporous NiFe2O4@g‐C3N4‐based p‐n Heterostructures for Boosting Solar‐Driven Photocatalytic Dye Degradation and Hydrogen Evolution

Mass‐fraction‐optimized heterojunction composites featuring precisely engineered interfaces and mesoporous structures are crucial for improving light absorption, minimizing electron‐hole recombination, and boosting overall catalytic efficiency. Herein, highly efficient mesoporous‐NiFe2O4@g‐C3N4 heterojunctions were developed by embedding p‐type NiFe2O4 nanoparticles (NPs) within n‐type porous ultrathin g‐C3N4 (p‐uCN) nanosheets. The optimized NiFe2O4@g‐C3N4, loaded with 20wt% magnetic counterparts, exhibits exceptional photocatalytic methylene blue degradation, achieving the highest performance in both photocatalytic and photo‐Fenton processes with rate constants of 0.062 and 0.161 min⁻¹, respectively. These performance metrics are 1.3 and 2.55 fold higher than p‐uCN (0.048 and 0.063 min⁻¹) and 51.6 and 17.4 fold higher than NiFO (0.0012 and 0.009 min⁻¹). Notably, mp‐NiF@uCN‐20% with 1.0 wt% of Pt loading achieves the highest H2 evolution rate of 2294 µmolg⁻¹h⁻¹, which is 3.72, 1.52, and 13.49 times higher than that of pure CN, p‐uCN, and NiFO, respectively. The enhanced performance is corroborated by increased surface area, improved separation of charge carriers, and effective charge transfer, which enables simultaneous reduction and oxidation processes. Further, the magnetic nanocomposite exhibits remarkable stability even after multiple runs, indicating their reusability. The experimental findings emphasize the importance of p‐n heterojunctions, interfacial band alignment, and mesoporous architecture in enhancing the photocatalytic efficiency of NiFe2O4@g‐C3N4 nanocomposites.

High performance Mg-Li dual metal-ion batteries based on highly pseudocapacitive hierarchical TiO2-B nanosheet assembled spheres cathodes.

Although Mg-Li dual metal-ion batteries are proposed as a superior system that unite safety of Mg-batteries and performance of Li-ion based systems, its practical implantation is limited due to the lack of reliable high performance cathodes. Herein, we report a high-performance Mg-Li dual metal-ion battery system based on highly pseudocapacitive hierarchical TiO2-B nanosheet assembled spheres (NS) cathode. This 2D cathode displayed exceptional pseudocapacitance (a maximum of 93%) specific capacity (303 mAh/g at 25 mA/g), rate performance (210 mAh/g at 1A/g), consistent cycling (retain ~100% capacity for 3000 cycles at 1A/g), coulombic efficiency (nearly 100%) and fast-charging (~12.1 min). These properties are remarkably dominant to the existing Mg-Li dual metal-ion battery cathodes. Spectroscopic and microscopic mechanistic studies confirmed negligible structural changes during charge-discharge cycles of the TiO2-B nanosheet assembled spheres electrodes. Exceptional electrochemical properties of the 2D electrode is ascribed to remarkable pseudocapacitive Mg-Li dual metal-ion diffusion via the numerous nanointerfaces of TiO2-B caused by its hierarchical microstrucrure. Large surface area, nanosheet morphology, mesoporous structure and ultrathin nature also acted as secondary factors facilitating improved electrode-electrolyte contact. Demonstrated approach of pseudocapacitive type Mg-Li dual metal-ion intercalation through hierarchical nanointerfaces may be further utilized for the designing of numerous top-notch electrode materials for futuristic Mg-Li dual metal-ion batteries&#xD.

Insights of Zinc Ion Storage in Chilli-Stem Derived Porous Carbon Enabling Ultrastability and High Energy Density of Zinc-Ion Hybrid Supercapacitors.

Aqueous zinc ion hybrid supercapacitors (ZIHSCs) are promising as low-cost and safe energy storage devices for next-generation applications. Still, their energy-power performance and durability are far from satisfactory. Here, we present an energy-dense, and ultrastable ZIHSC realized using activated porous carbons derived from chilli-stems. KOH activation resulted in a high specific surface area of 1710 m2/g, abundant mesoporous structure, and oxygen functionalities, which helped the KOH-activated carbon (CSK) to yield an impressive specific capacity and energy density of 192 mA h/g and 172 W h/kg, respectively, and makes it the top-performing ZIHSC in recent times. ZIHSC's cycling performance is exceptional, retaining over 90% capacity even after 50,000 charge-discharge cycles. Molecular dynamics simulations reveal easy Zn ion diffusion through interconnected channels and subsequent pore fillings within the carbon electrodes, rendering impressive performance. Simulations further reveal important atomic interactions, demonstrating that higher currents drawn from the device cause partial filling of pores and blockages in the channels and result in a decrease in the device's specific capacity. Benefitted by CSK's impressive performance, the aqueous Zn@pCu//CSK full-cell device has demonstrated good energy-power densities (57.7 W h/kg and 4.5 k W/kg) and durability over tens of thousands of cycles, further substantiating ZIHSCs' application prospects in real life.

Recent Advances in the Synthesis and Application of TS‐1 Zeolite for Green Catalytic Oxidation

AbstractTS‐1 has a unique structure, and TS‐1/H2O2 oxidation system for composition shows excellent catalytic performance in the oxidation of a variety of organic matter. The response conditions of the reaction system are mild, and the ultimate oxidation product is water. It is a typical “green catalytic” system and has received widespread attention from researchers. Here, the synthesis progress of TS‐1 to improve the accessibility and activity of active sites by doping mesoporous and microporous structures into traditional TS‐1 zeolite in recent five years are reviewed, including hydrothermal synthesis, dry gel conversion synthesis, solvent‐free synthesis, microwave assisted synthesis, and isomorphous substitution. Meanwhile, the application of TS‐1/H2O2 system in oxidative desulfurization, ketone ammonia oxidation, olefin epoxidation, and hydroxylation of aromatic hydrocarbons reactions are summarized and discussed. What's more, the reaction mechanism based on TS‐1/H2O2 system is proposed on regarding the isolated skeleton Ti site in titanium‐silicon zeolite as the active central site. Finally, the challenges and future development prospects of TS‐1 zeolite in synthesis and catalytic applications are predicted.

3D Printing of Graphene Aerogel Microspheres to Architect High-Performance Electrodes for Hydrogen Evolution Reaction.

The hydrogen evolution reaction (HER) efficiency is highly dependent on the electrocatalysts microstructure and the macrostructure of the electrodes. Herein, the graphene aerogel microspheres loaded with well-dispersed ultrafine Ni/Co nanoparticles catalyst is prepared through electro-spraying, in-situ crosslinking, freeze-drying, and pyrolysis, and then is utilized to print the HER electrode via direct ink writing (DIW). The obtained graphene-based aerogel microspheres possess peculiar cabbage-like mesoporous structures which allow ready access of reaction species to active sites, optimal mass transfer, and proton diffusion within the microspheres. DIW 3D printing achieves the ordered control on the periodic lattice macro-geometry and thus facilitates the fast gas bubble evolution and release from the electrode surface. The as-fabricated 3D electrode possesses a low overpotential of 341 mV at 10 mA cm-2, a decrease by 31.5% compared to 3D printed electrode directly from 2D graphene, and a low Tafel slope of 119.1 mV dec-1, 40% lower than that of the electrodes fabricated via directly casting the aerogel microspheres. Furthermore, the 3D-printed electrode of aerogel microspheres displays good HER stability. This work provides a good approach for constructing high-performance HER electrodes through 3D printing of graphene aerogel microspheres.

Mesoporous Atomically Dispersed Fe Catalysts with Enhanced Nonradical Pathways in Fenton-like Reactions: The Role of SiO2 Templates.

Single-atom catalysts (SACs) are extensively applied in Fenton-like catalytic processes to treat water pollutants. However, the role of the porous structures of SACs supports in catalytic reactions is often overlooked despite its significant contribution to mass diffusion during the reaction. Herein, we adopted a hard-template-assisted approach to fabricate Fe-based SACs (Fe-SACs) featuring a mesoporous architecture. The SiO2 template not only adjusts the pore architecture of the support but also facilitates the conversion of active sites from nanoscale sites to single-atom sites, thereby improving the selectivity for pollutant degradation via nonradical pathways (singlet oxygen and electron transfer mechanism). The experimental results demonstrated that using large-sized SiO2 (∼200 nm) as a template leads to metal aggregation on its surface, forming Fe nanoparticles (Fe-NPs). Fe-NPs exhibit narrow pore structures that prevent peroxymonosulfate (PMS) from being activated, resulting in a slow degradation of pollutants primarily through radical pathways. In contrast, employing small-sized SiO2 (∼10 nm) as a hard template not only produces supports with mesoporous structures but also promotes the building of single-atom active sites. The prepared Fe-SACs effectively activated PMS through nonradical pathways and removed contaminants at a rate k of 0.89 min-1, 33 times faster than Fe-NPs. This template-assisted method sheds light on the synthesis of effective Fenton-like catalysts with porous structures that enhance the efficient breakdown of contaminants in wastewater.

Boron modification of AuRh mesoporous nanotubes for electro-reduction of nitrogen to ammonia.

Electrocatalytic nitrogen reduction reaction (NRR) is a prospective tactics for ammonia synthesis. However, the development of highly active NRR electrocatalysts is still challenging owing to the difficult activation of nitrogen and competitive hydrogen evolution reaction (HER). Here, we synthesized boron-doped AuRh mesoporous nanotubes (B-AuRh MNTs) via dual-template method coupled with boron doping. The mesoporous nanotube structure has high specific surface area and excellent surface permeability. Thereby, the B-AuRh MNTs exhibit NH3 yield of 13.3 μg h-1 mg-1cat and Faraday efficiency of 22.5% under 0.1 M Na2SO4. The doping of boron with weak hydrogen adsorption can generate electronic effect, thus stimulating the activation of N2 molecules and effectively inhibiting HER. This study proposes a universal method for the preparation of boron-doped Pd-based catalysts, which is beneficial to improve the NRR performance.&#xD.

Mesoporous silica-modified metal organic frameworks derived bimetallic electrocatalysts for oxygen reduction reaction in microbial fuel cells

The design of cost-effective oxygen reduction reaction (ORR) catalysts in microbial fuel cells (MFCs) remains a challenge. Herein, a mesoporous silica (mSiO2) assisted protection strategy is developed to synthesize highly dispersed CuCo nanoalloys embedded in nitrogen doped carbon Cu/Co-NC@mS catalyst using zeolitic imidazolate framework (ZIF) as carbon and nitrogen sources. The results revealed that the mSiO2 protection holds the potential to inhabit CuCo nanoalloys from aggregation and thus promotes the formation of highly dispersed small CuCo nanoparticles. The obtained catalyst with pyrolysis temperature (T) of 800 °C (Cu/Co-NC@mS-800) achieves the best ORR performance among Cu/Co-NC@mS-T catalysts, yielding a maximum power density of 1000 mW m−2 when employed as air cathode MFCs. The significantly enhanced ORR performance of Cu/Co-NC@mS-800 could be attributed to following aspects: a) highly dispersed small CuCo nanoalloy particles, improved mesoporous surface area and volume owing to mSiO2 protection; (b) the formation of concave regular dodecahedron mesoporous structure with thin graphtic carbon layer as support; (c) the synergetic effect between CuCo nanoalloys. This work provides a facile strategy for the preparation of highly dispersed bimetal nanoalloys with enhanced electrocatalytic performance for energy-related applications.

Phosphoric acid-modified bentonite-chitosan composite beads: a novel and cost-effective adsorbent for multi-metal wastewater treatment.

This study introduces a novel, cost-effective adsorbent made from phosphoric acid-modified bentonite-chitosan composite beads, designed to remove Cu2⁺, Ni2⁺, and Zn2⁺ from aqueous solutions. Characterization of the composite revealed a mesoporous structure and the presence of functional groups that enhance its adsorption properties. Using response surface methodology, the adsorption capacities were determined as 362.24mg/g for Cu2⁺, 279.51mg/g for Ni2⁺, and 210.54mg/g for Zn2⁺ under optimal conditions. A pH study further improved the adsorption capacities to 381.29mg/g for Cu2⁺, 305.98mg/g for Ni2⁺, and 225.04mg/g for Zn2⁺. The adsorption process followed pseudo-second-order kinetics and was best described by the Langmuir isotherm model, suggesting that the adsorption occurred on a single layer of the adsorbent surface via chemical bonds. In competitive adsorption scenarios, Cu2⁺ was removed more efficiently than Zn2⁺ and Ni2⁺. The removal efficiencies achieved were 88.59% for Cu2⁺, 72.30% for Ni2⁺, and 62.07% for Zn2⁺ using 1g/l adsorbent within 30min for treating industrial effluent. Thermodynamic analysis confirmed that the adsorption process was spontaneous and endothermic. The adsorbent maintained good performance over 10 regeneration cycles, demonstrating its reusability. The primary adsorption mechanisms include electrostatic attraction, surface complexation, and ion exchange. The developed adsorbent proved to be an efficient, sustainable, and environmentally friendly solution for removing heavy metals from wastewater. This cost-effective material can be readily implemented in industrial wastewater treatment plants to tackle heavy metal contamination.

Box-shaped necklace-like Fe3O4/MoS2-CNFs composite nanofibers with confinement effect enhancing sodium storage performance

A nanofiber necklace with a box-shaped structure has been designed. The box-shaped template can introduce other transition metal compounds, effectively compensating for the intrinsic defects of electrode materials. α-Fe2O3 nano cubes as the template mix with PAN to get α-Fe2O3/PAN. And then the α-Fe2O3 nano cubes calcine to form Fe3O4 with more valence state under high temperature, which get the box-shape necklace-like structure Fe3O4-CNFs. The confined space has formed by high concentrated HCl etching, the box-shaped necklace-like Fe3O4/MoS2 carbon nanofibers (BN Fe3O4/MoS2-CNFs) anode material is obtained by hydrothermal method of confining growth of MoS2 nanosheets. The mixed valence state of Fe3O4 (Fe3+/Fe2+) can effectively improve the conductivity of MoS2 nanosheets. The box-shape necklace structure constructed by α-Fe2O3 nanocube has mesoporous structure and confined space, which can alleviate the volume effect of electrode material. When the electrode material is applied to the SIBs, the reversible capacity is 354 mA h g−1 after 500 cycles at 0.5 A/g, and the specific capacity of 131.5 mA h g−1 can be maintained at 8 A/g. On the one hand, the heterogeneous structure in the confined space alleviates the volume effect of the material, thereby improving the long cycle performance, on the other hand, it effectively enhances the electrical conductivity and increases more lithium/sodium storage sites.

Constructing a 3D ordered macroporous cobalt monoatomic catalyst for efficient SMX degradation via PMS activation

The cobalt monoatomic catalyst with 3D ordered macropores structure (3DOM Co/NC) was prepared using the crystalline porous material ZIF-67 and SiO2 as the precursor and template, and used to investigate the effect of its activation with peroxymonosulfate (PMS) on sulfamethoxazole (SMX) removal. The mesoporous structure mostly retained after ZIF-67 carbonisation, and the formation of new homogeneous macropores after the removal of the SiO2 template, which greatly increases the surface area of the catalyst (429 m2 g-1) and promotes long-range mass transfer. Additionally, Co monoatomic sites were formed in the porous skeleton, providing electrons that were utilised for the activation of PMS. This distinctive structure enables it to almost completely degrade of 20 ppm SMX within 3min and show excellent catalytic degradation efficiency in a wide pH range (3.0-9.0) and high-salinity simulated wastewater (10-100mM). In addition, the main ROS in the catalytic degradation process were explored as 1O2 and O•2-. Combined with the results of DFT calculations and product analyses, the active sites of SMX were predicted and the degradation pathways and mechanisms were inferred, confirming that the degradation process of SMX poses a low risk of toxicity to the environment. This study reveals that the addition of 3DOM Co/NC was more favourable for the activation of PMS for SMX degradation, which contributes to the development and improvement of advanced oxidation processes for environmental remediation.

Efficient hybrid supercapacitor performance enabled by large surface area of 2D mesoporous zinc sulfide nano-sheets synthesized via microwaves

Researchers have shown a significant amount of interest in synthesizing high energy density supercapacitors using a simplest, fast, and low cost technique. The electrochemical performance of supercapacitors can be impacted by the surface area and morphology of electrode materials. A one-step, rapid, and economical microwave-assisted synthesis technique was employed in this study in order to prepare mesoporous nanosheets that are composed of zinc sulfide. The ZnS-based nanosheets possess a large surface area of ∼120 m2g−1 and a mesoporous structure of a pore diameter of <22 nm, which offers numerous electrochemical active sites and it facilitates an excellent super capacitive performance, which is due to its shortened ion/electron diffusion path. The prepared mesoporous nanosheets exhibit a higher specific capacitance of 2282 Fg−1 (1037 C/g) when subjected to a 1 Ag−1 in 2 M KOH aqueous electrolyte with high capability rate. The fabricated device exhibits a high specific capacitance of 252.5 Fg−1 (140 C/g) at 1 Ag−1, which produces a remarkable energy density of about 90 Whkg−1 at 800 Wkg−1 value of power density and an excellent retention of ∼95 % after 10,000 cycles at 6 Ag−1. This study designed an instant, straightforward and low-cost approach to fabricate ZnS nanosheet electrode materials that exhibit excellent performance for supercapacitor applications.

Ultra-small CoxSy nanoparticles adhered to 3D-reduced graphene oxide as attractive anodes for lithium-ion batteries

A novel composite anode material, CoxSy/G, has been developed through a novel hydrothermal synthesis method complemented by an innovative high-temperature vulcanization technique. This process facilitates the deposition of CoxSy nanoparticles, each less than 10nm in size, onto a substrate of 3D rGO. This composite material combines the robust lithium storage capacity of CoxSy nanoparticles with the exceptional electrical conductivity and mechanical resilience of the 3D rGO framework, resulting in a significantly enhanced specific surface area and optimized mesoporous structure for CoxSy/G. Furthermore, it exhibits excellent electrochemical performance in lithium-ion batteries. Specifically, the CoxSy/G composites achieve a discharge capacity of 748.5mAh g⁻¹ at 50mAg⁻¹, notably exceeding the 647mAh g⁻¹ capacity demonstrated by pure CoxSy. Furthermore, these composites maintain an extraordinary cycle retention rate of 112.4% after undergoing 500 charge-discharge cycles at a continuous rate of 0.5Ag⁻¹. The reduced charge transfer resistance noted after cycling underscores the material’s enhanced performance attributes. This innovative creation of CoxSy/G composites offers critical insights and potential strategies for further development in the field of lithium-ion cobalt-sulfur electrodes.

Construction of Fe and g-C3N4 codoped magnetic bamboo charcoal for enhanced catalytic degradation of tetracycline: Mechanism, degradation pathway, and ecological toxicity.

The well-designed bamboo charcoal (BC) composite Fe-g-C3N4/BC with multi-active sites of FeOx, FeNx, and g-C3N4, was fabricated in-situ by calcining Fe-melamine loaded bamboo charcoal (Fe-Me-BC) under nitrogen atmosphere. The as-synthesized Fe-g-C3N4/BC(550) exhibited a mesoporous structure with a large specific surface area of 108.23 m2/g. The adsorption of tetracycline (TCL) on Fe-g-C3N4/BC(550) was calculated following the Langmuir isotherm model, and showed a maximum adsorption capacity of 19.92 mg/g. Furthermore, the pseudo-second-order kinetic model showed a good fit for the TCL adsorption process on Fe-g-C3N4/BC(550). The Fe-g-C3N4/BC(550)/H2O2 system exhibited excellent photo-Fenton catalytic performance in degrading TCL with a degradation efficiency reaching up to 98.9% within 5 min under visible-light. The effects of initial pH value and coexisting anions on TCL degradation were determined. As narrow band gap semiconductors, g-C3N4, Fe3O4, and Fe2O3 in the Fe-g-C3N4/BC exhibited good visible-light-driven photocatalytic activity. Moreover, photogenerated electrons could further activate H2O2 to produce high concentrations of ∙OH radicals. This outstanding photo-Fenton catalytic performance can be ascribed to the synergistic effect of g-C3N4/Fe3O4-Fe2O3/FexN multi-active sites as well as the excellent adsorption ability and conductivity provided by bamboo charcoal. This work presents a convenient approach for constructing economical catalysts for environmental remediation through g-C3N4 and Fe-N codoped BC.

Multi-enzyme-immobilized robust self-floating covalent organic framework/chitosan aerogels for the efficient remediation of emerging pollutants in water

Organic contaminants of emerging concern (OCECs) as a new class of organic pollutants have initiated intense global concerns. The efficient enzymatic water treatment was consider the crucial for the potential remediation process. However, the widespread application of enzymatic systems faces significant obstacles, including low enzyme activity and the lower value of recovery. Thus, a novel multi-enzymes immobilized biocatalytic system (multi-enzyme@COF@Chitosan aerogels) was synthesized via the combine the in-situ direct immobilization process and double-cross linking strategy in this study. Results showed that multi-enzyme@COF@Chitosan aerogels exhibits good mesoporous structure (the pore size distribution is 2.5nm) and mechanical strength, leading to remarkable stability a broader pH range (4-7) and temperature range (30~70 ℃). For typical OCECs, including 2-mercaptobenzothiazole (MBT), paracetamol (PCM), sulfamethoxazole (SMO), bisphenol A (BPA), Sulfamerazine (SMR), the remediation activities reached 100%, 87%, 68%, 69%, and 100%, respectively. Likewise, the multi-enzyme@COF@Chitosan aerogels exhibited good reusability, with the relative activity still maintained approximately 75.7% after seven cycles. Moreover, the electrochemical characteristics of multi-enzymes@COF@Chitosan aerogel and enzymes activities were contributed to degradation the OCECs.

Accurate HER2 determination in breast cancer: a prominent COF-immobilized enzyme-enhanced electrochemical aptasensor employing 4-acetamidophenol as an efficient mediator

An effective strategy for enzyme-enhanced electrochemical detection of human epidermal growth factor receptor 2 (HER2) is proposed for breast cancer diagnosis. This strategy utilizes a three-dimensional mesoporous covalent organic framework (COF), immobilized horseradish peroxidase (HRP), and a novel redox mediator, 4-acetamidophenol (APAP). The mesoporous structure, with encapsulation effect, and good biocompatibility of COF, makes the functionalized COF an efficient carrier for HRP immobilization (HRP-Ab-AuNPs@COF). It demonstrates superior catalytic activity, stability, and electrochemical performance compared to free HRP, thus making it an ideal probe for simultaneous target recognition and signal amplification. APAP is screened from four candidate phenolic compounds based on its high formal potential (0.32 V vs. Ag/AgCl), rapid electron transfer activity (kapp = 2.80 × 105 M− 1 s− 1), excellent solubility and stability. These properties prove significantly better than the conventional mediator hydroquinone (HQ), achieving a higher signal-to-background ratio. By integrating decorated multi-walled carbon nanotubes as substrate materials, the electrochemical aptasensor achieves a low HER2 detection limit (0.418 pg mL− 1) with high specificity. This method’s selectivity surpasses that of the HQ-mediated method by 59–73%. Moreover, the aptasensor can effectively distinguish breast cancer patients and healthy individuals, as well as patients at different stages of the disease with high accuracy (AUC = 0.928). This performance exceeds traditional biomarkers CEA and CA15-3. This work paves novel avenues for innovative applications of COF-immobilized enzymes and the novel mediator APAP in electrochemical biosensing, thus holding significant promise for individualized breast cancer diagnosis and treatment.

Regenerable nickel catalysts strengthened against H2S poisoning in dry reforming of methane

In this study, alumina-supported bimetallic Ni-Cu and trimetallic Ni-Cu-Ce catalysts were synthesized to improve catalysts resistant to coke formation and sulfur poisoning for dry reforming of methane (DRM). The effects of parameters such as feed composition, synthesis method, and H2S concentration using the catalyst with the best activity were also investigated. To determine the physical and chemical properties of the synthesized catalysts, XRD, N2 adsorption–desorption, TGA-DTA, ICP-OES, SEM-EDX, XPS, and DRIFTS analyses were performed. XRD analysis showed that the fresh Ni-Cu catalysts have elemental nickel and γ-alumina phases in their structures. In addition to these structures, the CeO2 crystal structure was determined for the Ni-Cu-Ce catalyst. Type IV isotherm with H1 hysteresis indicating uniform mesoporous structure was obtained with all the catalysts. The activities of the synthesized catalysts in DRM were performed in the presence of different concentrations of H2S (2 ppm, 50 ppm, and 500 ppm) in a fixed bed reactor at 750 °C using a gas chromatography-equipped system. The alumina-supported 8Ni-3Cu-8Ce catalyst prepared by the impregnation method exhibited a higher and more stable activity comparing the bimetallic Ni-Cu catalyst in the presence of H2S. Adding copper and cerium to the nickel catalyst has a curative effect on resistance to coke formation and sulfur poisoning. Excess CO2 in the feed stream increased the H2S poisoning resistance of the catalyst. To analyze the reactor exit stream in catalytic activity using different feed stream compositions such as H2S+He, H2S+CO2+He, and H2S+CO2+CH4+He, FTIR with a gas cell was used. The formation of carbonyl sulfide (COS) and H2O, which occurs due to the possible reaction between CO2 and H2S, was observed. Regeneration studies showed that the catalyst could undergo regeneration with a low oxygen concentration (0.3 % O2 in He). 8Ni-3Cu-8Ce@SGA, which gave 71 % CH4 conversion in the first minute of the reaction test in the presence of 50 ppm H2S, was regenerated after completely losing its activity at the end of 5 h. 66 % CH4 conversion was achieved when tested again in the absence of H2S (CH4/CO2/Ar:1/1/1). The 8Ni-3Cu-8Ce@SGA catalyst was deemed worthy of investigation for industrial applications.

Construction dual active sites on confined ordered mesoporous CeWTi catalyst by CuSO4 modification for enhancing SO2 tolerance during low temperature NH3-SCR process

The full exposure of the active center is an important reason for the superior performance, and the excellent anti-SO2 poisoning ability is a key factor to ensure the service life for the low temperature NH3-SCR catalyst. In this study, the strategy of evaporation-induced self-assembly (EISA) was chosen to directly confined CuSO4 to the framework structure of ordered mesoporous CeWTiOx (CWT-OM) catalyst. Metal sulfate plays a dual role in low temperature activity and sulfur resistance. When the temperature reached 220 °C, the NO conversion of ordered mesoporous CuSO4/CeWTiOx (CuCWT-OM) catalyst reached about 90 %. Introduce 100 ppm SO2 17.5 h under 260 °C, the conversion of CuCWT-OM catalyst can keep the above 80 %. The introduction of CuSO4 increased the acidity of CWT-OM catalyst, inhibited the sulfate formed by the reaction of SO2 with active species, and ensured the number of active sites in the reaction. In addition, the Cu-Ce interface effect accelerates the electron transfer frequency between the active species, stimulates the production of adsorbed NO2, and promotes the conversion of NO at low temperature. Furthermore, the interface confined effect and the framework confined effect make the active species Cu and Ce firmly confined in the ordered mesoporous framework structure, and reduce the action of SO2 on the active components. In addition, SO42− is more likely to react with W species, protecting the main active species Ce and inhibiting its acidification. This work provides a new feasible idea for improving the low temperature activity and anti-SO2 poisoning stability of Ce based catalyst.

Performance Analysis of Effective Methylene Blue Immobilization by Carbon Microspheres Obtained from Hydrothermally Processed Fructose

Carbon microspheres have been synthesized by the hydrothermal method with fructose and a phosphoric acid solution at two different concentrations, which were used as precursors. The obtained materials were characterized by elemental analysis, X-ray powder diffraction (XRPD) analysis, scanning electron microscopy (SEM), nitrogen adsorption/desorption measurements, and Fourier transform infrared (FTIR) spectroscopy. Batch sorption experiments were performed to remove methylene blue (MB) from aqueous solutions by varying the initial concentration of MB (C0) from 50 to 500 mg/dm3, contact period, solution pH value, and temperature. Prepared sorbents consisted of microsphere particles with diameters in the range of 0.6–2.7 µm. The synthetic route was found to govern the microporous–mesoporous structure and surface acidic functional groups of the final product. A phosphoric acid concentration of 40 wt.% gave carbon material with a specific surface area of 932 m2/g and a total pore volume of 0.43 cm3/g. It was found that the extent of MB sorption by the obtained carbon microspheres increased with initial dye concentration, contact time, and especially solution pH but slightly decreased with increasing temperature. Kinetic studies showed that the dye sorption process followed pseudo-second-order kinetics.

Enhancing Biocatalysis: Metal-Organic Frameworks as Multifunctional Enzyme Hosts.

ConspectusEnzymes are highly efficient and selective catalysts that operate under mild conditions, making them invaluable for various chemical transformations. However, their limitations, such as instability and high cost, call for advancements in enzyme immobilization and the development of suitable host materials. Metal-organic frameworks (MOFs), characterized by high porosity, crystallinity, and tunability, are promising candidates for enzyme encapsulation. Among these, zirconium-based MOFs (Zr-MOFs) stand out due to their exceptional structural diversity and chemical stability. The physical and chemical properties of Zr-MOFs can be tuned and characterized with atomic precision, and their interactions with enzymes can be analyzed through a range of techniques spanning from chemistry and materials science to biochemistry. This tunable platform provides opportunities to systematically investigate the impact of encapsulation on the stability and activity of enzymes in order to develop design rules for enzyme hosts.In this Account, we discuss experimentally validated concepts for designing MOF hosts based on their structural properties and enzyme encapsulation mechanisms. We present methods to enhance enzyme catalytic performance through encapsulation and strategies for creating multifunctional enzyme@MOF systems via host modifications. We start by highlighting the importance of host structural design that maximizes substrate diffusion and enzyme availability, with particular focus on MOFs containing hierarchical mesoporous structures such as those in the csq topology. We then delve into the encapsulation process and host-guest interactions examined through techniques such as microscopy, calorimetry, and computational methods, which provide guidelines to fine-tune the local pore chemical environment to enhance enzyme stability and catalytic activity. Techniques found in biochemistry, such as isothermal titration calorimetry (ITC) and confocal laser scanning microscopy (CLSM), were developed to investigate enzyme encapsulation mechanisms, revealing high-entropy-driven host-guest affinity. Additionally, we discuss cases in which enzyme@MOF systems demonstrated enhanced catalytic activities and multifunctional capabilities. Encapsulated enzymes have demonstrated improved thermal and chemical stabilities compared to their free counterparts, maintaining activity under conditions that typically lead to denaturation. Additionally, the highly tunable nature of the MOF platforms allows them to support more complex systems such as tandem reactions, enabling applications in biophotocatalysis, bioelectrocatalysis, and targeted therapeutic protein delivery.The versatility of enzyme@MOFs promises extensive applications in both research and industrial processes across fields including biotechnology, pharmaceutical development, and environmental science. We provide an outlook for promising directions for enzyme@MOF research, with the aim of continuing innovation and exploration. We hope that this Account can benefit chemists, biologists, and material scientists toward designing efficient and adaptable next-generation biocatalytic composite materials.