Mesoporous Oxide Research Articles

Influence of Ordered Mesoporous Oxides in Plasma-Assisted Ammonia Synthesis

Influence of Ordered Mesoporous Oxides in Plasma-Assisted Ammonia Synthesis

Solvothermal Synthesis of Medium-Entropy Oxide Spheres for Thermocatalytic Conversion of CO2 to Methanol.

New chemical compositions and structures for medium- and high-entropy oxides (HEOs) currently represent a promising new avenue in materials research for a wide range of applications including catalysis, energy storage, and ceramics. To speed up further development, synthesis methods for multicationic oxides are needed for controlling features like morphology, porosity, and chemical compositions. In this work, mesoporous spinel oxide spheres with five cations are synthesized using solvothermal synthesis techniques. The targeted chemistry included Co, Al, Fe, and Cr as the first four cations, where the fifth cation was varied by increasing cation radii (Ga, In, Yb, Ho, or Ce). After calcination, all as-synthesized precursors led to mesoporous oxide spheres with spinel oxide structures. In order to demonstrate an example of applicability for targeting different M3+ cations, the sample containing Co, Al, Fe, Cr, and In was tested in a model reaction of thermocatalytic CO2 hydrogenation and is shown to be active with a preference to methanol formation (58% selectivity, 7.8% conversion at 300 °C). The synthesis of multicationic mesoporous spheres appears to be quite flexible in terms of possible M3+ cations compositions and is a potential material to combine targeted chemistry for applications like catalysis.

Mesoporous Electrodes Enhance the Electrocatalytic Performance of [FeFe]-Hydrogenase.

The metalloenzyme [FeFe]-hydrogenase is of interest to future biotechnologies targeting the production of "green" hydrogen (H2). We recently developed a simple two-step functionalized procedure to immobilize the [FeFe]-hydrogenase from Clostridium pasteurianum ("CpI") on mesoporous indium tin oxide (ITO) electrodes to achieve elevated H2 production with high operational stability, with current densities of 8 mA cm-2. Here, we use a combination of atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical quartz crystal microbalance (EQCM) to understand how mesoporous ITO stabilizes and activates CpI for electroenzymatic H2 production. Examination of the topography and morphology of the mesoporous ITO surface revealed a hierarchical morphology containing cavities and well-defined nanoparticle agglomerates. Any potential effect of mesoporosity was investigated by comparing the stability and electroenzymatic activity of CpI on mesoporous 'nanoITO' and planar ITO, where we determined that CpI has a higher turnover frequency and absorbs with greater stability (with respect to electroenzymatic activity over time) to nanoITO surfaces.

Mesoporous Electrodes Enhance the Electrocatalytic Performance of [FeFe]‐Hydrogenase

The metalloenzyme [FeFe]‐hydrogenase is of interest to future biotechnologies targeting the production of “green” hydrogen (H2). We recently developed a simple two‐step functionalized procedure to immobilize the [FeFe]‐hydrogenase from Clostridium pasteurianum (“CpI”) on mesoporous indium tin oxide (ITO) electrodes to achieve elevated H2 production with high operational stability, with current densities of 8 mA cm–2. Here, we use a combination of atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical quartz crystal microbalance (EQCM) to understand how mesoporous ITO stabilizes and activates CpI for electroenzymatic H2 production. Examination of the topography and morphology of the mesoporous ITO surface revealed a hierarchical morphology containing cavities and well‐defined nanoparticle agglomerates. Any potential effect of mesoporosity was investigated by comparing the stability and electroenzymatic activity of CpI on mesoporous ‘nanoITO’ and planar ITO, where we determined that CpI has a higher turnover frequency and absorbs with greater stability (with respect to electroenzymatic activity over time) to nanoITO surfaces.

Temperature and Ultrasound-Responsive Nanoassemblies for Enhanced Organ Targeting and Reduced Cardiac Toxicity.

Biocompatible nanocarriers are widely employed as drug-delivery vehicles for treatment. Nevertheless, indiscriminate drug release, insufficient organ-specific targeting, and systemic toxicity hamper nanocarrier effectiveness. Stimuli-responsive nano-sized drug delivery systems (DDS) are an important strategy for enhancing drug delivery efficiency and reducing unexpected drug release. This study introduces a temperature- and ultrasound-responsive nano-DDS in which the copolymer p-(MEO2MA-co-THPMA) is grafted onto mesoporous iron oxide nanoparticles (MIONs) to construct an MPL-p nano-DDS. The copolymer acts as a nanopore gatekeeper, assuming an open conformation at sub-physiological temperatures that allows drug encapsulation and a closed conformation at physiological temperatures that prevents unexpected drug release during circulation. Lactoferrin was conjugated to the nanoparticle surface via polyethylene glycol to gain organ-targeting ability. External ultrasonic irradiation of the nanoparticles in the targeted organs caused a conformational change of the copolymer and reopened the pores, facilitating controlled drug release. MPL-p exhibited excellent biocompatibility and rare drug release in circulation. When targeting delivery to the brain, ultrasound promoted the release of the loaded drugs in the brain without accumulation in other organs, avoiding the related adverse reactions, specifically those affecting the heart. This study established a novel temperature- and ultrasound-responsive DDS that reduced systemic adverse reactions compared with traditional DDS, especially in the heart, and demonstrated excellent organ delivery efficiency.

The Swiss Army Knife of Electrodes: Pillar[6]arene-Modified Electrodes for Molecular Electrocatalysis Over a Wide pH Range.

Molecularly-modified electrode materials that maintain stability over a broad pH range are rare. Typically, each electrochemical transformation necessitates a specifically tuned system to achieve strong binding and high activity of the catalyst. Here, we report the functionalisation of mesoporous indium tin oxide (mITO) electrodes with the macrocyclic host molecule pillar[6]arene (PA[6]). These electrodes are stable within the pH range of 2.4-10.8 and can be equipped with electrochemically active ruthenium complexes through host-guest interactions to perform various oxidation reactions. Benzyl alcohol oxidation serves as a model reaction in acidic media, while ammonia oxidation is conducted to assess the systems performance under basic conditions. PA[6]-modified electrodes demonstrate catalytic activity for both reactions when complexed to different guest molecules and can be reused by reabsorption of the catalyst after its degradation. Furthermore, the system can be employed to perform subsequent reactions in electrolyte with varying pH, enabling the same electrode to be utilised in multiple different electrocatalytic reactions.

The Swiss Army Knife of Electrodes: Pillar[6]arene‐Modified Electrodes for Molecular Electrocatalysis Over a Wide pH Range

AbstractMolecularly‐modified electrode materials that maintain stability over a broad pH range are rare. Typically, each electrochemical transformation necessitates a specifically tuned system to achieve strong binding and high activity of the catalyst. Here, we report the functionalisation of mesoporous indium tin oxide (mITO) electrodes with the macrocyclic host molecule pillar[6]arene (PA[6]). These electrodes are stable within the pH range of 2.4–10.8 and can be equipped with electrochemically active ruthenium complexes through host–guest interactions to perform various oxidation reactions. Benzyl alcohol oxidation serves as a model reaction in acidic media, while ammonia oxidation is conducted to assess the systems performance under basic conditions. PA[6]‐modified electrodes demonstrate catalytic activity for both reactions when complexed to different guest molecules and can be reused by reabsorption of the catalyst after its degradation. Furthermore, the system can be employed to perform subsequent reactions in electrolyte with varying pH, enabling the same electrode to be utilised in multiple different electrocatalytic reactions.

Mesoporous cerium oxide nanoenzyme for Efficacious impeding tumor and metastasis via Conferring resistance to anoikis

Tumor cells can survive when detached from the extracellular matrix or lose cell-to-cell connections, leading to a phenomenon known as anoikis resistance (AR). AR is closely associated with the metastasis and proliferation of tumor cells, enabling them to disseminate, migrate, and invade after detachment. Here, we have investigated a novel composite nanoenzyme comprising mesoporous silica/nano-cerium oxide (MSN-Ce@SP/PEG). This nanoenzyme exhibited satisfactory catalase (CAT) activity, efficiently converting high levels of H2O2 within tumor cells into O2, effectively alleviating tumor hypoxia. Furthermore, MSN-Ce@SP/PEG nanoenzyme demonstrated high peroxidase (POD) activity, elevating reactive oxygen species (ROS) levels and attenuating AR in hepatocellular carcinoma (HCC) cells. The MSN-Ce@SP/PEG nanoenzyme exhibited satisfactory dual bioactivity in CAT and POD and was significantly enhanced under favorable photothermal conditions. Through the synergistic effects of these capabilities, the nanoenzyme disrupted the epithelial-mesenchymal transition (EMT) process in detached HCC cells, ultimately inhibiting the recurrence and metastasis potential of anoikis-resistant HCC cells. This study represents the first report of a novel nanoenzyme based on mesoporous silica/nano-cerium oxide for treating AR in HCC cells, thereby suppressing HCC recurrence and metastasis. The findings of this work offer a pioneering perspective for the development of innovative strategies to prevent the recurrence and metastasis of HCC.

New Suggestion of Highly Durable Electrode Design for Ordered Mesoporous Ni-Mn Binary Transition Metal Oxide Anode Material in Lithium-Ion Batteries.

Anode materials storing large-scale lithium ions gradually decrease electrochemical performance due to severe volume changes during cycling. Therefore, there is an urgent need to develop anode materials with high electrochemical capacity and durability, without deterioration arising due to the volume changes during the electrochemical processes. To date, mesoporous materials have received attention as anode materials due to their ability to mitigate volume expansion, offer a short pathway for Li+ transport, and exhibit anomalous high capacity. However, the nano-frameworks of transition metal oxide collapse during conversion reactions, demanding an improvement in nano-framework structure stability. In this study, ordered mesoporous nickel manganese oxide (m-NMO) is designed as an anode material with a highly durable nanostructure. Interestingly, m-NMO showed better cycle performance and higher electrochemical capacity than those of nickel oxide and manganese oxide. Operando small-angle X-ray scattering and ex situ transmission electron microscopic results confirmed that the binary m-NMO sustained a highly durable nanostructure upon cycling, unlike the single metal oxide electrodes where the mesostructures collapsed. Ex situ X-ray absorption spectroscopy proved that nickel and manganese showed different electrochemical reaction voltages, and thus undergoes sequential conversion reactions. As a result, both elements can act as complementary nano-propping buffers to maintain stable mesostructure.

Structural modification of mesoporous lanthanum oxide into 3D coral-like and nano needle-like structure for effective broadband microwave absorbing materials☆

Structural modification of three dimensional (3D) materials for the application of dielectric loss-based microwave absorbing materials (MAMs) usually relies on intricate synthesis process and can pose challenges in terms of scalability and mass production for practical application. In this work, we reported a successful attempt in modifying the 3D structure of mesoporous lanthanum oxide (La2O3) for effective broadband MAMs candidate via simple co-precipitation process. The inclusion of cetyl-trimethylammonium bromide (CTAB) and hydrothermal aging treatment result in a significant transformation of La2O3 particles from their original polygonal form to a 3D coral-like and nano needle-like structure. The utilization of CTAB and hydrothermal aging results in the increase of surface area and a two-fold increase in pore volume of the resulting La2O3. Due to its unique 3D structure, the 3D coral-like and nano needle-like La2O3 materials possess a broadband electromagnetic (EM) wave absorption characteristic with the effective absorption bandwidth (EAB) covering the C-band frequency range. Specifically, in the La2O3 C-H sample (with CTAB – with hydrothermal), it exhibits strong EM wave absorption with a reflection loss (RL) value of –33.07 dB which equals to 99.95% EM wave absorption at a thickness of only 1.50 mm. The detailed analysis of EM wave absorption properties reveals that the improvement of La2O3 materials to attenuate EM wave energy arises from the dielectric loss phenomenon, the enhanced interfacial polarization, multiple reflections mechanism, and conduction loss mechanism induced by the 3D structural formation of the La2O3 structure. This work proposes a novel and efficient approach in synthesizing and modifying 3D materials for effective broadband EM wave absorption.

Effect of iron oxidation state on the catalytic performance of Fe/C in liquid phase flow hydrogenation of 2-butyne-1,4-diol

Cis-2-butene-1,4-diol and 1,4-butanediol are crucial precursors in producing bioplastics and biodegradable plastics. Moreover, cis-2-butene-1,4-diol is used in the production of vitamins A and B6, fungicides and insecticides. On an industrial scale, they are produced by hydrogenation of 2-butyne-1,4-diol with Ni Raney as catalyst at > 160 °C and > 15 MPa. Herein, the effect of mesoporous carbon, iron loading (2, 6, 10 and 14 wt%), and metal oxidation state on the activity and selectivity of iron catalysts in the liquid phase continuous flow 2-butyne-1,4-diol hydrogenation at mild conditions (at temperature range 10–65 °C and pressure range 1–20 bar) was performed. Catalytic investigations supported by statistical modeling and physicochemical characterization (TPR, H2-TPD, physisorption, TEM, XPS, and Mössbauer spectroscopy), showed that the activity of the Fe/C can be determined by the presence of functional groups in mesoporous support which are responsible for high metal dispersion and strong metal-support interaction, which boosts the catalytic activity of iron catalysts. Additionally, the formation of metastable iron carbides which are active in hydrogenation cannot be excluded. All of the catalysts showed 100% selectivity toward cis-2-butene-1,4-diol at the lowest temperature. However, the best compromise between selectivity and activity (TOF=336 h−1) was achieved with 2 wt% Fe at 1 bar and 25 °C.

Development of mesoporous magnetic nanoparticles supported idarubicin and investigation of apoptotic and cytotoxic effects on cancer cell lines.

Many methods are used for cancer treatment, especially chemotherapy. In addition to the their therapeutic effects, chemotherapeutic drugs also have serious disadvantages, such as not being cell and tissue-specific, causing toxicity in many tissues, and developing drug resistance. Many methods, especially nanocarriers, have been designed to overcome these disadvantages. In this study, we synthesized mesoporous silica iron oxide nanoparticles with different pore diameters and loaded idarubicin (6MFe3O4-NH2-IDA and 35MFe3O4-NH2-IDA). The synthesized molecules were characterized using FT-IR, XRD, and SEM methods. The cytotoxic effects of unbound idarubicin and idarubicin-loaded nanoparticles on MCF7 and HL-60 cell lines were examined by MTT test. Additionally, the expression of anti-apoptotic (Survivin and BCL-2) and apoptotic (BAX, PUMA, and NOXA) genes of the nanoparticles were measured by PCR method. As a result of the analyses, it was seen that nanoparticles with the desired properties and sizes were synthesized. In MTT analysis, it was observed that both nanoparticles dramatically decreased the IC50 value in cell lines. However, the 35MFe3O4-NH2-IDA molecule was found to have lower IC50 values. IC50 values ​​for pristine IDA, 6MFe3O4-NH2, and 35MFe3O4-NH2 at 24h were found to be 3.56, 1.24 and 0.25 µM in the MCF7 cell line and 4.15, 1.16 and 0.34 µM in the HL-60 cell line, respectively. Additionally, apoptotic gene expression increased, and anti-apoptotic gene expression decreased. Our study demonstrates that the effectiveness of idarubicin can be significantly enhanced by its application with mesoporous nanocarriers. This enhancement is attributed to the controlled release of idarubicin from the nanocarrier, which circumvents drug resistance mechanisms, improves drug solubility, and increases the drug-carrying capacity per unit volume due to the porous structure of the carrier. These findings underscore the potential of the synthesized nanocarrier in cancer treatment and provide a clear direction for future research in this field.

Sustainable approach with enhanced removal performance of organic pollutant for wastewater treatment by ultrasonically regenerated mesoporous nickel oxide nanoparticles

Sustainable approach with enhanced removal performance of organic pollutant for wastewater treatment by ultrasonically regenerated mesoporous nickel oxide nanoparticles

A Comparative Study of Ni-Based Catalysts Prepared by Various Sol-Gel Routes.

The use of heterogeneous catalysts to increase the development of green chemistry is a rapidly growing area of research to save industry money. In this paper, mesoporous SiO2-Al2O3 mixed oxide supports with various Si/Al ratios were prepared using two different sol-gel routes: hydrolytic sol-gel (HSG) and non-hydrolytic sol-gel (NHSG). The HSG route was investigated in both acidic and basic media, while the NHSG was explored in the presence of ethanol and diisopropyl ether as oxygen donors. The resulting SiO2-Al2O3 mixed oxide supports were characterized using EDX, N2 physisorption, powder XRD, 29Si, 27Al MAS-NMR and NH3-TPD. The mesoporous SiO2-Al2O3 supports prepared by NHSG seemed to be more regularly distributed and also more acidic. Consequently, a simple one-step NHSG (ether and alcohol routes) was selected to prepare mesoporous and acidic SiO2-Al2O3-NiO mixed oxide catalysts, which were then evaluated in ethylene oligomerization. The samples prepared by the NHSG ether route showed better activity than those prepared by the NHSG alcohol route in the oligomerization of ethylene at 150 °C.

A Chemotherapy-Photothermal synergistic system in bifunctional bone Scaffold: Tumor therapy and bone repair

Bone defect repair and tumor recurrence are the main challenges in the postoperative treatment of bone tumors. The incorporation of zoledronate (ZOL) into scaffolds presents a promising approach, attributed to its osteogenic and anti-tumor properties. However, there are still some unfavorable factors that make it difficult to eradicate tumor cells at the surgical site, including drug rapid release, the insufficient anti-tumor efficacy of ZOL and the multidrug resistance of chemotherapy. Herein, a novel nano drug delivery platform mesoporous silicon-coated graphene oxide (GO/MSN) and ZOL loaded nanoparticle (GO/MSN-ZOL) were developed. Then PLLA/ GO/MSN-ZOL scaffold that integrates photothermal therapy (PTT) and chemotherapy was fabricated using poly (L-lactic acid) as raw materials by selective laser sintering (SLS) technology. The GO not only imparted scaffold with photothermal properties for localized tumor cell ablation but also significantly enhanced its anti-tumor efficacy through synergistic effects in combination with chemotherapy. The mesoporous structure and large specific surface area of MSN contribute to the sustained release of ZOL. Additionally, GO could promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), which in combine with ZOL’s osteoclast inhibition, enhances the bone repair capacity. This study offers a straightforward and promising strategy for treating tumor-related bone defects.

Metal cation and crystal lattice water molecule stabilized highly mesoporous manganese oxide network for excellent durable electrode in sodium-ion storage

Potassium birnessite is a remarkable material with a wider inter-planar spacing, which enables to accommodate more electrolytic ions to improve overall electrochemical performances. In this work, controlled synthesis of K0.46Mn2O4(H2O)1.4 (HKMO) nanosheets were interconnected mesoporous networks uniformly grown on carbon cloth (CC) via a one-step hydrothermal process. Specifically, the HKMO sample synthesized at 100 °C for 12 h (100@HKMO-12 h) exhibited a mesoporous morphology with a large specific surface area. The binder-free 100@HKMO-12 h electrode exhibits a maximum specific capacitance of 255F g−1 (323F cm−3) in 1 M NaClO4/acetonitrile electrolyte over a broad potential range of 3 V. DFT studies demonstrated the interlayer distance increased by the insertion of K+ ions into the MnO2 matrix. Bader charge analysis showed a 12.09 |e| charge difference for K-birnessite in the inter-layer region compared to the normal birnessite, supported the increase of inter-layer region in the MnO2 matrix. Significantly, the increased interlayer the distance, promoted rapid intercalation/deintercalation of Na+ ions and allowed the reversible faradic pseudocapacitance reaction to occur at a wider potential window. Moreover, the symmetric full-cell fabricated utilizing the 100@HKMO-12 h electrodes have a wide voltage of 2 V and the device delivered a maximum specific energy of 43 Wh kg−1 (28 Wh cm−3) at a minimum specific power of 556 W Kg−1 (349 W cm−3). Besides, the device showed an excellent capacitance retention of ∼94 % even after 10,000 continuous charge–discharge cycles at a current of 5 A/g, indicating it is a potential candidate for next-generation sodium energy storage devices.

Facile synthesis of mesoporous zinc oxide nanoparticle as a drug delivery system evaluated by IVIVE in PBPK modeling

This study focuses on the development of mesoporous zinc oxide nanoparticles (mZNPs) via the sol–gel technique, utilizing polyethylene glycol-6000 (PEG-6000) as a capping agent. The research aims to investigate the suitability of these nanoparticles for drug delivery purposes. The analysis of the synthesized material validates the existence of a hexagonal system of zinc oxide with space group P6 3cm and HRTM confirmed the crystallinity and morphology of the nanoparticles ranging from 15–20 nm, revealing the formation of pores attributed to the presence of PEG-6000. The mZNPs exhibit a BET surface area of 28.3 m2. g−1, with Langmuir surface area measurements indicating 46 m2. g−1. Analysis employing the BJH method outlines pore diameters ranging from approximately 2–5 nm at a relative pressure of around 0.99. Furthermore, these mZNPs demonstrated drug delivery attributes, with 43.3% loading efficiency and 80.33% entrapment efficiency for aspirin. Notably, the release kinetics of aspirin from the mZNPs were investigated in simulated fluids of varying pH, with the highest release (98.1%) observed in simulated intestinal fluid (pH 6.8). The formulation exhibits typical time-dependent release kinetics under mild pH conditions (7.4 and 6.8), while transitioning to erosion-controlled diffusion mechanisms in acidic pH conditions (1.2). Furthermore, mathematical models, including Higuchi’s, Korsmeyer’s, and Weibull’s, were employed to assess release kinetics, offering parameters for in-vitro to in-vivo pharmacokinetic predictions. In the framework of PBPK modeling, renal clearance was computationally simulated at a rate of 45 min−1, whereas biliary clearance was modeled to occur at 0.05 min−1. Utilizing these model-derived parameters, the projected half-life of aspirin administered via mZNPs was determined to be 3.1 h. The potential applications of these findings extend to the development of effective drug delivery systems, warranting consideration for future animal model studies involving aspirin and mZNPs.

Imparting of Nearly Superparamagnetic Properties to Cryogel Scaffolds With Mesoporous MNPs for Magneto-Sensitive Tissue Engineering Strategies.

This work reports the assembly of mesoporous iron oxide nanoparticles (meso-MNPs) with cryogel scaffolds composed of chitosan and gelatin. Meso-MNPs with a particle size ranging from 2 and 50 nm, a surface area of 140.52 m2 g-1, and a pore volume of 0.27 cm3 g-1 were synthesized on a porous SiO2 template in the presence of PEG 6000 followed by leaching of SiO2. Different ratios of meso-MNPs were successfully incorporated into chitosan:gelatin cryogels up to an amount equivalent to the entire amount of polymer. The morphological structure and physicochemical properties of the cryogels were directly affected by the amount of MNPs. VSM curves showed that all composite cryogels could be magnetized by applying a magnetic field. In the context of the safety of magnetic cryogel scaffolds for use in biomedicine, it is important to note that all values are below the exposure limit for static magnetic fields, and according to cytotoxicity data, scaffolds containing meso-MNPs showed nontoxicity with cell viability ranging from 150% to 275%. In addition, microbial analysis with gram-negative and gram-positive bacteria showed that the scaffolds exhibited activity against these bacteria.

Humidity-Controlling Ceramic Bricks: Enhancing Evaporative Cooling Efficiency to Mitigate Urban Heat Island Effect

Passive evaporative cooling technology using the building envelope is a crucial measure to mitigate the urban heat island effect. This study aims to enhance the cooling efficiency of the surface of enclosure structures by utilizing volcanic ash, potassium–sodium stone powder, and silica-based mesoporous oxide (SMO) as primary materials. These components are incorporated into the ceramic brick production process to create innovative humidity-controlling ceramic bricks (HCCTs). This study extensively investigates the impact of SMO and the amount of applied glaze on the physical and mechanical characteristics of these HCCTs. Additionally, it examines the water absorption and evaporative cooling properties of the studied materials under optimal substitution conditions. Numerical calculations are used to determine the heat and moisture transfer properties of HCCTs. The results indicate that incorporating 2% SMO and applying 70 g/m2 of glaze results in a moisture absorption capacity of 385 g/m2 and a moisture discharge capacity of 370 g/m2. These conditions also yield a notable flexural strength of 15.2 MPa. Importantly, the HCCTs exhibit significantly enhanced capillary water absorption and water retention capabilities. Increased water absorption reduces surface temperature by 2–3 °C, maintaining the evaporative cooling effect for 20 to 30 h. It is also found that the temperature of HCCTs decreases linearly with increasing water content and porosity, while the temperature difference gradually decreases with thickness. Water migration in HCCTs with greater thickness is notably influenced by gravity, with water moving from top to bottom. Therefore, it is recommended that brick thickness does not exceed 15 mm.

Efficient adsorption and desorption of elemental mercury by ordered mesoporous cerium oxide nanoparticles derived from Ce-based metal–organic frameworks

Metal oxide-based adsorbents not only exhibit effective elemental mercury (Hg0) removal capacity but also offer suitability for wet desorption, which is a green treatment method to avoid secondary contamination of deactivated adsorbents. Nevertheless, the limited dispersing capacity of the carrier restricts the loading of active substances, hindering further enhancement of adsorption capacity. The pore structure of adsorbent is also a key factor for wet desorption. In this work, we synthesized a hollow cerium-based metal–organic framework (Ce-mesoMOF) as a sacrificial precursor to obtain ordered mesoporous cerium oxide (OM-CeO₂) via a mesoporous genetic pyrolysis-oxidation mechanism. OM-CeO2 inherits the excellent structural properties of mesoporous MOF with better catalytic activity, exhibiting strong adsorption capacity in various atmospheres (97.6 % in pure N2, 98.8 % in N2 + H2S). Wet desorption of Hg compounds and reduction of the active site can be synergized in Na2S2O3 solution. The octahedral structure with an ordered mesoporous shell greatly facilitates the mass transfer process, as evidenced by the strong adsorption capacity and fast kinetic parameters of OM-CeO2. Density functional theory analysis reveals that the conversion reaction of adsorbed Hg has a low energy barrier on the pyrolytic-oxidized OM-CeO2 and the inhibitory effect of reactive S for Hg0 adsorption transforms into a facilitating effect. This study leverages the structural advantages of ordered mesoporous MOFs in the field of Hg adsorption and imparts reactivity through modification for efficient adsorption–desorption.