Mesoporous Carbon CMK-3 Research Articles

Dual-layer coated photocatalytic membranes for surface water treatment: Insight of membrane fouling restriction

The combination of carbon-based material adsorption and photocatalytic oxidation is a crucial approach to eliminate natural organic substances and mitigate membrane fouling induced by them. In this investigation, Bi2O3-TiO2 (BT) was incorporated with three varieties of carbon-based substances (such as powdered activated carbon (PAC), ordered mesoporous carbon CMK-3 (OMCs), and carbon nanotubes (CNTs)) and employed as a dual-layer coating on the surface of the ultrafiltration membrane to reduce membrane fouling induced by natural organics during the treatment of actual water bodies. Under light conditions, the BT/CMK-3 coating outperforms BT/PAC and BT/CNTs coatings in reducing membrane fouling, with a flux recovery rate of up to 80.4 % and an irreversible fouling rate as low as 19.5 %, while also improving the removal rates of UV254 and DOC to 55.2 % and 77.9 %, respectively. Based on the analyses of three-dimensional fluorescence PARAFAC and liquid chromatography, the BT/CMK-3 coating efficiently removes humic substances and protein-like compounds via adsorption and photocatalytic oxidation, achieving a 24.1 % removal rate of humic acid and a 93.7 % removal rate of low molecular weight neutral substances. Under the synergy of CMK-3 adsorption and BT photocatalytic oxidation, reactive oxygen species effectively degraded and transformed the membrane foulants enriched by CMK-3, reducing and increasing the Zeta potential and free energy on the membrane surface to −4.2 mV and 15.1mJ/m2, respectively. The interaction force between the foulant and the membrane changed into a repulsive force, and the fouling mechanism changed from complete blockage to intermediate blockage, thereby shortening the transition time. This advancement provides significant promise for the development and broader application of photocatalytic membrane filtration technology.

Cobalt-catalyzed carbonization from polyacrylonitrile for preparing nitrogen-containing ordered mesoporous carbon CMK-1 electrode with high electric double-layer capacitance

Ordered mesoporous carbon CMK-1 was prepared via carbonization at a relatively low temperature (the first step) followed by partial graphitization (the second step of carbonization at higher temperature) inside the ordered mesopores of cobalt-loaded mesoporous silica MCM-48 using polyacrylonitrile (PAN) as a carbon/nitrogen source. This first step of the carbonization is called “infusibilization”, and the resultant material is denoted as PANinf. In an advanced temperature-programmed desorption analysis of the PANinf/MCM-48 composite, the temperature of the observed HCN signal indicated that carbonization was reduced from 550 to 450 °C by a Co catalyst. The amount of typical N2 formation associated with the selective removal of pyridinic N species, resulting in the graphitic surface formation, also increased at a relatively high temperature (approximately 1000 °C) with the aid of the Co catalyst. The CMK-1 prepared through cobalt-catalyzed carbonization exhibited a higher electric double-layer capacitance with an Et4N+BF4–/propylene carbonate electrolyte, and higher electrical conductivity than CMK-1 prepared without a catalyst. This also implied the progress of graphitization within the carbonaceous wall. These results suggest that the edge planes of the graphitic domains in CMK-1 are predominantly exposed on the surfaces of the carbonaceous walls, resulting in an increase in the number of adsorptive sites for the electrolyte during capacitance measurements.

Modified CMK-3 carbon materials for efficient removal of roxarsone

Roxarsone adsorption from water using ordered mesoporous carbon CMK-3 (P_CMK-3) and CMK-3 carbon modified with thiourea (TU_CMK-3) or diclofenac (SD_CMK-3) was studied. The adsorption of roxarsone occurred at low pH. The adsorption was fast; in the case of SD_CMK-3 and TU_CMK-3 materials, the adsorption equilibrium was achieved within 2 min, whereas in the case of P_CMK-3 material, within 30 min. The adsorption capacities towards roxarsone were 130, 99, and 200 mg/g for P_CMK-3, TU_CMK-3, and SD_CMK-3, respectively. Coexistence of 20 mg/L Ca2+, Mg2+, Fe3+; Cl-, HCO3–, SO42-, NO3–, and PO43- ions did not significantly hinder the adsorption of roxarsone onto SD_CMK-3 material. The NaOH solution application enabled virtually complete roxarsone desorption from the SD_CMK-3 surface. It was found that the adsorption of roxarsone on the SD_CMK-3 material is a complex process occurring as a result of the electrostatic interaction of anionic forms of roxarsone with a positively charged surface, hydrogen bonds, and the interactions between carbon and the aromatic ring in roxarsone. Adsorption is accompanied by partial reduction of –ONO2 groups in the roxarsone molecule and partial transformation of organic As contained in the roxarsone molecule to As(V).

Nanostructured Magnetic Particles for Removing Cyanotoxins: Assessing Effectiveness and Toxicity In Vitro.

The rise in cyanobacterial blooms due to eutrophication and climate change has increased cyanotoxin presence in water. Most current water treatment plants do not effectively remove these toxins, posing a potential risk to public health. This study introduces a water treatment approach using nanostructured beads containing magnetic nanoparticles (MNPs) for easy removal from liquid suspension, coated with different adsorbent materials to eliminate cyanotoxins. Thirteen particle types were produced using activated carbon, CMK-3 mesoporous carbon, graphene, chitosan, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidised cellulose nanofibers (TOCNF), esterified pectin, and calcined lignin as an adsorbent component. The particles' effectiveness for detoxification of microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-A (ATX-A) was assessed in an aqueous solution. Two particle compositions presented the best adsorption characteristics for the most common cyanotoxins. In the conditions tested, mesoporous carbon nanostructured particles, P1-CMK3, provide good removal of MC-LR and Merck-activated carbon nanostructured particles, P9-MAC, can remove ATX-A and CYN with high and fair efficacy, respectively. Additionally, in vitro toxicity of water treated with each particle type was evaluated in cultured cell lines, revealing no alteration of viability in human renal, neuronal, hepatic, and intestinal cells. Although further research is needed to fully characterise this new water treatment approach, it appears to be a safe, practical, and effective method for eliminating cyanotoxins from water.

Understanding adsorption mechanisms and metal ion selectivity of superparamagnetic beads with mesoporous CMK-3 carbon and commercial activated carbon

This study investigates, the adsorption capacities of synthesized magnetic hybrid beads containing ordered mesoporous carbon (CMK-3) and commercial activated carbon (commercial AC) for Cd (II), Ni (II), and Hg (II) ions adsorption in single and ternary systems. The order of maximum adsorption capacity was Cd (II) > Ni (II) > Hg (II) in both beads and systems. L13 beads containing CMK-3 exhibit superior adsorption efficiency compared to L3 beads with commercial AC, attributed to the large surface area, enhanced accessibility to adsorption sites, and the presence of O=C bonds, as well as other elements such as F−. Adsorption of all metal ions was described by Freundlich isotherm in L3 beads in both systems, meanwhile in L13 beads, Langmuir and Freundlich models described adsorption differently in both systems and among metal ions, indicating a more complex process. According to the reported maximum adsorption capacity values, L3 beads exhibit a greater affinity for Hg (II) ions, while L13 beads show a higher affinity for Cd (II) and Ni (II) ions. Adsorption in both beads occurred through several mechanisms involving surface complexation, ion-exchange, precipitation, physical and chemical processes. These findings highlight the importance of material design in optimizing adsorption performance for environmental applications, with potential for further enhancement of adsorption capacities and selectivities through future research.

Preparation of inexpensive S-doped porous carbons for high-performance supercapacitors

Low-cost sulfur-doped porous carbons were prepared through hard template method by using inexpensive colloidal SiO2 nanoparticles as template, glucose as carbon source, H2SO4 as pre‑carbonized reagent and sulfur source. The effects of H2SO4 and carbonization temperature on the microscopic morphology, the pore structure and the specific surface area of porous carbons were explored through multiple characterization methods. The capacitive performance of porous carbons was investigated by multiple electrochemical methods. It was found that the pore structure, specific surface area and the content of sulfur element of carbon are highly dependent on the carbonization temperature. The sulfur-doped porous carbon SPC-900 has much larger surface area and larger pore volume, and thus much better capacitive performance than un-doped PC-900, indicating that H2SO4 can increase the surface area and the pore volume during the preparation process. SPC-900 offers the advantages of lower cost, larger pore size, higher pore volume, better capacitive performance and better rate performance compared to expensive mesoporous carbon CMK-3. In the three-electrode system, the specific capacitance of SPC-900 can reach 363 F g−1, whereas that of PC-900 is only 164 F g−1 at a current density of 0.5 A g−1. The double layer capacitance (EDLC) and pseudocapacitance can both be increased by the sulfur element, according to the capacitive contribution study. Additionally, the SPC-900 can maintain its initial specific capacitance of 98.1 % for 10,000 cycles at a current density of 0.5 A g−1, demonstrating both its high cycling performance and potential for practical applications.

Supported Pd NPs over polydopamine modified-ordered mesoporous carbon (CMK-3) as an efficient and recyclable nanocatalyst for oxidative esterification of arylaldehydes

The high surface area carbonaceous materials have been proven as an outstanding biodegradable and biocompatible material as support in heterogeneous catalysis for immobilizing active metal species. In this research work, a hitherto unreported novel material has been synthesized based on surface functionalized CMK-3 mesoporous carbon upon which the in situ prepared Pd nanoparticles (NPs) are immobilized following a simple, green and inexpensive procedure. The covalently bonded polydopamine moieties were exploited as the natural and safe reducing agents in pursuing the green reduction of Pd ions anchored over the surface. The as synthesized nanomaterial was characterized by advanced techniques like EDS, elemental mapping, TEM, SEM, XRD and ICP-OES. Subsequently, catalytic activity of this heterogeneous material CMK-3@PDA/Pd was assessed in the oxidative esterification of a range of arylaldehydes with methanol with excellent efficiency producing very good yields. Mild reaction condition in synthesis of catalyst, simple workup, unparallel catalytic activity with excellent yields, and very good reusability are the advantages of this method.

Sustainably Sourced Mesoporous Carbon Molecular Sieves as Immobilization Matrices for Enzymatic Biofuel Cell Applications

Ordered mesoporous carbon CMK-3 sieves with a hexagonal structure and uniform pore size have recently emerged as promising materials for applications as adsorbents and electrodes. In this study, using sucrose as the sustainable carbon source and SBA-15 as a template, CMK-3 sieves are synthesized to form bioelectrocatalytic immobilization matrices for enzymatic biofuel cell (EFC) electrodes. Their electrochemical performance, capacitive features, and the stability of enzyme immobilization are analyzed and compared to commercially available multi-walled carbon nanotubes (MWCNT) using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The anodic reaction in the presence of glucose oxidase (GOx) and ferrocene methanol (FcMeOH) on the sustainably sourced CMK-3-based electrodes produces bioelectrocatalytic current responses at 0.5 V vs. saturated calomel electrode (SCE) that are twice as high as on the MWCNT-based electrodes under saturated glucose conditions. For the cathodic reaction, the MWCNT-based cathode performs marginally better than the CMK-3-based electrodes in the presence of bilirubin oxidase (BOD) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS2−). The CMK-3-based EFCs assembled from the GOx anode and BOD cathode results in a power output of 93 μW cm−2. In contrast, the output power of MWCNT-based EFCs is approximately 53 μW cm−2. The efficiency of CMK-3 as a support material for biofuel cell applications is effectively demonstrated.

Nanoarchitectonics of high-performance supercapacitors based on mesoporous carbon and MnO2 electrodes using Aquivion electrolyte membrane

Mesoporous carbons can contribute to the development of high energy and high-power density energy storage devices due to their tunable pore structures, high surface area and excellent electrical conductivity. The well-known mesoporous carbon CMK-3 with a hierarchical nanoporous structure can be promising candidate as electrode materials for supercapacitors to achieve high performance. Herein, we have produced a series of well-ordered mesoporous carbon materials with nano-sized structural units adopting two methods of synthesis: i) standard method and ii) ultrasonication assisted synthesis. Mesoporous carbons with hierarchical porous features and high surface area were obtained by both methods, and symmetrical supercapacitors containing these carbons and using an Aquivion membrane as polymer electrolyte were subsequently fabricated. Specific capacitance values of 66 and 78 F g−1 at 0.2 A g−1 were found for sonication assisted synthesised carbon (USC) and standard method derived carbon (SMC), respectively. Furthermore, the fabricated SMC//MnO2 supercapacitor with asymmetric configuration delivers a capacitance performance of 95 F g−1 and presents a low self-discharge rate if charged for 3 h at 1.6 V. This asymmetric supercapacitor device, as-assembled, also demonstrates a long-term durability of more than 10,000 galvanostatic charge and discharge cycles and 150 h under floating conditions at 1.6 V, which is among the best asymmetric supercapacitors developed.

Effective modulating of the Mo dissolution and polymerization in Ni4Mo/NiMoO4 heterostructure via metal-metal oxide-support interaction for boosting H2 production

Constructing low-cost, high-active and robust heterogeneous hydrogen evolution reaction (HER) electrocatalysts with strong metal–metal oxide-support interaction (SMMOSI) is still an urgent challenge for the development of anion exchange membrane water electrolysis (AEMWE), especially under high current density (e.g., 1 A cm−2). Herein, a hierarchical composite of heterogenous Ni4Mo/NiMoO4 (NiMoOx) nanoparticles (NPs) anchored on a mesoporous carbon CMK-3 (NiMoOx@CMK-3) is designed as a superior electrocatalyst for HER. Significantly, the strong interaction between heterogeneous NiMoOx NPs and CMK-3 supporting matrix effectively stabilize the catalytic active Ni4Mo/NiMoO4 heterostructure by altering the local geometric and electronic structures, leading to maximumly exposure of active sites and promoted electron transfer ability. The optimized electrocatalyst exhibits outstanding HER activity with an extremely low overpotential and Tafel slope of 7 mV@10 mA cm−2 and 27.7 mV dec-1, respectively, and can steadily operate at 100 mA cm−2 for 800 h. More significantly, owing to these HER merits, the AEMWE configuration with NiMoOx@CMK-3 (−) is also designed, resulting in low cell voltage of 1.965 V@1 A cm−2 and negligible degradation over 400 h@1 A cm−2. Further ex/in-situ electrochemical spectra evidence that both the partial combined MoO42- from NiMoO4 and the newly formed MoO42- originating from dissolved Mo in NiMoOx@CMK-3 could boost the fast generation of polymerized Mo2O72- that could effectively accelerate the HER process in alkaline conditions by facilitating the formation of active Mo-H* intermediates. Moreover, theoretical calculation results demonstrate the upshifting of d-band center of Mo toward Fermi level for the heterogeneous NiMoOx and the strong charge distribution between the heterointerface could optimize adsorption free energies of H* (ΔGH*) on the surface of Mo atoms.

KVPO4F/carbon nanocomposite with highly accessible active sites and robust chemical bonds for advanced potassium-ion batteries

KVPO4F (KVPF) has been extensively investigated as the potential cathode material for potassium-ion batteries (PIBs) owing to its high theoretical capacity, superior operating voltage, and three-dimensional K+ conduction pathway. Nevertheless, the electrochemical behavior of KVPF is limited by the inherent poor electronic conductivity of the phosphate framework and unstable electrode/electrolyte interface. To address the above issues, this work proposes an infiltration-calcination method to confine the in-situ grown KVPF into the mesoporous carbon CMK-3 (denoted KVPF@CMK-3). The assembled KVPF@CMK-3 nanocomposite features three-dimensional interconnected carbon channels, which not only offer abundant active sites and significantly accelerate K+/electron transport, but also prevent the growth of KVPF nanoparticle agglomerates, hence stabilizing the structure of the material. Additionally, V–F–C bonds are created at the interface of KVPF and CMK-3, which reduce the loss of F and stabilize the electrode interface. Thus, when tested as a cathode material for PIBs, the KVPF@CMK-3 nanocomposite delivers superior reversible capacitiy (103.2 mAh g−1 at 0.2 C), outstanding rate performance (90.1 mAh g−1 at 20 C), and steady cycling performance (92.2 mAh g−1 at 10 C and with the retention of 88.2% after 500 cycles). Moreover, its potassium storage mechanism is further examined by ex-situ XRD and ex-situ XPS techniques. The above synthetic strategy demonstrates the potential of KVPF@CMK-3 to be applied as the cathode for PIBs.

Effect of peroxydisulfate oxidation catalyzed with ordered mesoporous carbons on controlling ultrafiltration membrane fouling by algal organic matter.

As typical ordered mesoporous carbons (OMCs) materials, CMK-3 and CMK-8 were proposed for catalyzing peroxydisulfate (PDS), and the OMCs/PDS process was combined with membrane filtration to remove algal extracellular organic matter and mitigate membrane fouling. The CMK-3/PDS process achieved substantial reduction of dissolved organic carbon and UV254, followed by CMK-8/PDS. The degradation behavior of fluorescent organics demonstrated the superior performance of OMCs/PDS, while the decomposition of high molecular weight (MW) compounds and generation of lower MW organics were observed. Generally, CMK-3 possessed higher catalytic activity on PDS compared with CMK-8 and powdered activated carbon. The CMK-3/PDS process distinctly decreased the fouling resistances for polyether sulfone and polyvinylidene fluoride membranes, with the reversible resistance reduced by 59.5-83.2% and irreversible resistance declined by 71.7-73.0%. In the meanwhile, CMK-3/PDS prolonged the volumes to the transition period, and postponed the cake layer's generation. The characterization of the membrane morphologies and chemical compositions also showed effective alleviation of fouling. The generated SO4-, OH, O2- and 1O2 as major active oxidation species provided radical as well as non-radical reaction ways for pollutants removal. Overall, our study provides some new ideas for membrane-based combined water purification processes.

Detection of CYFRA21-1 in serum by electrochemical immunosensor based on nanocomposite consisting of AuNPs@CMK-3@CMWCNTs

An electrochemical immunosensor based on the modification of nanocomposite was constructed to detect the lung cancer marker Cytokeratin 19 fragment antigen 21-1 (CYFRA21-1). Ordered mesoporous carbon CMK-3 was selected to mix with carboxylated multi-walled carbon nanotubes (CMWCNTs), and their combination could enhance electron transfer efficiency and amplify the electrochemical signal. Furthermore, aurum nanoparticles (AuNPs) were further mixed with the hybrid carbon nanomaterials, which bind antibodies via Au-S bonds and provide numerous of binding sites for antibodies. Finally, CYFRA21-1 could be detected by specific immune response between antigen and antibody by improving the immunosensor sensitivity. The characterization of scanning electron microscopy (SEM) showed that AuNPs were embedded on the surface and interstices of CMK-3@CMWCNTs. The curves of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that the immunsensor was successfully constructed. The constructed immunosensor had a linear range of 0.5 pg/mL to 105 pg/mL for the detection of CYFRA21-1 in serum, and the correlation coefficient (r) was 0.998, with a detection limit of 0.2 pg/mL. Thus, this method is selective and sensitive for getting the accurate and reliable detection results and provides a new method for the CYFRA21-1 ultrasensitive detection in serum.

Fluorinated cobalt phthalocyanine axially coordinated to oxo functionalities on different dimensional carbon (1D–3D) for durable oxygen reduction reaction

The development of low-cost, durable and easily available electrocatalysts as alternatives to Pt-based catalysts for the oxygen reduction reaction (ORR) will promote the large-scale commercial application of fuel cells and metal-air batteries. Among the transition metal based N4-metallomacrocyclic molecules, the Co macrocycle catalyst usually exhibits superior long-term durability and stability than the Fe family. Developing efficient Co-N4 ORR electrocatalyst is of great significance. In the work, fluorinated cobalt phthalocyanine (CoPcF16) were anchored on various carbon materials in different structural dimensions (1–3D) including 1D carboxyl carbon nanotube (CNT), 1D carbon nanofibers (CNF), 2D nitrogen doped graphene (N-G), and 3D ordered mesoporous carbon CMK-3, which were explored and investigated as electrocatalysts for ORR. The results show that the molecular CoPcF16 anchored on theses carbon materials exhibited different electrocatalytic activity with the increased half-wave potential (E1/2) order of CMK-3>CNT>N-G>CNF, which is related to oxo functionalities (axial coordination to Co), porous structures and defective sites. The CoPcF16-carbons hybrids exhibited much lower tafel slope and comparable E1/2 than commercial Pt/C catalysts for ORR. The prepared catalysts also demonstrated excellent stability even after 5000 cycling. CoPcF16-carbons hybrids will be potential candidates to replace Pt-based catalysts for PEMFCs applications in future.

Synthesis of modified, ordered mesoporous carbon-supported Pt3Cu catalyst for enhancing the oxygen reduction activity and durability

The modification of carbon-supported components plays an important role in increasing the interaction between carbon-supported and metal-active components in the application of PEMFC catalysts. Here, we propose a strategy for designing a catalyst by covalently modifying ordered mesoporous carbon (MC) CMK-3 and loading Pt3Cu onto modified, ordered mesoporous carbon. Ammonium persulfate (APS) was used as a modifying agent. The surface chemistry and structural properties of the modified mesoporous carbon (MMC) were characterized by BET, XPS, Raman, etc. As a result, the MMC retains the original ordered structure and introduces many oxygen-containing functional groups on the surface of MMC. Due to the optimized properties of MMC, the Pt3Cu/MMC have shown excellent mass activity of 0.58 A/mgPt, which are twice that of Pt3Cu/MC and 4.8 times of JM Pt/C. Besides, the durability test showed that after 10 K cycles, the mass activity loss was only 12.06%, exhibiting excellent electrochemical stability. In addition, the MEA shows a high power density up to 641 mW cm−2, which demonstrate a great potential of modified mesoporous carbon catalyst in practical application.

High-voltage lithium-metal battery with three-dimensional mesoporous carbon anode host and ether/carbonate binary electrolyte

Electrolyte recipes and Li metal anode host materials are developed for lithium-metal batteries. 1,2-dimethoxyethane/ethylene carbonate mixed solvent with 1 M lithium bis(fluorosulfonyl)imide and 1 wt% LiNO3 is shown to form a robust solid electrolyte interphase and improve Coulombic efficiency and cyclability during Li metal plating/stripping. This electrolyte can withstand high potential, allowing the operation of a LiNi0.8Co0.1Mn0.1O2 (NMC-811) cathode. One-dimensional carbon nanotubes, two-dimensional graphene nanosheets, and three-dimensional ordered mesoporous carbon CMK-8 are used as the host materials for the accommodation of Li metal. The strong and continuous conducting network of CMK-8 with interpenetrating open channels is found to be a promising scaffold for Li metal. With the proposed electrolyte, the CMK-8 electrode enables uniform Li plating/stripping with a high Coulombic efficiency of 99.2% under a practical current density of 1 mA cm−2. Moreover, a long life of >550 charge-discharge cycles is achieved. The high structural stability of CMK-8 upon cycling is confirmed using electron microscopy and Raman spectroscopy. Finally, we use a Li-free CMK-8 electrode, an NMC-811 cathode, and the proposed electrolyte to construct a full cell. The electrochemical properties are evaluated.

Glycerol electrooxidation catalyzed by Pt-Sb supported in periodic mesoporous carbon CMK-3 and CMK-5

Glycerol is a biomass-derivative feedstock with potential use in direct alcohol fuel cells. In this work, we have studied the influence of distinct carbon-supports for Pt-Sb catalysts applied to glycerol electrooxidation reaction. The carbon matrixes were synthesized from Si templates with distinct geometries, giving the so-called CMK-3 and CMK-5, whose 3D structures were characterized employing SAXS, TGA, TEM, and N2 adsorption isotherms. Pt nanoparticles were synthesized onto the carbon structures (Pt/Cx within X = CMK-3, CMK-5, or Vulcan) and converted to Pt-Sb/C catalysts by irreversible Sb2O3 adsorption on Pt/Cx covering up to 97% of Pt surface as inferred by cyclic voltammograms. Regardless of the carbon support, the onset of glycerol oxidation on Pt-Sb/C is ca 0.4 V (vs RHE), however, at higher potentials in cyclic voltammetric conditions or chroamperometric curves, Pt-Sb/CCMK-3 depicted the best activity among the synthesized catalysts, providing currents 1.6 and 2.0 times bigger than those in Pt-Sb/CCMK-5 and Pt-Sb/CVulcan, respectively after 800 s at 0.5 V. The results are explained utilizing the coupled between the glycerol mass transport from bulk to active sites in carbon matrixes and re-adsorption of partially oxidized reaction products.

One-step elimination of Cr(VI) by catalytic hydrogenation of Cr(VI) and simultaneous Cr(OH)3 recovery on Pt catalysts encapsulated in N-doped mesoporous carbon

Hexavalent chromium Cr(VI) is a highly toxic heavy metal, which is commonly eliminated by stepwise reduction at acidic pH and precipitation of Cr(OH)3 at alkaline pH. A unique Pt catalyst with Pt particles embedded in the framework of N-doped mesoporous carbon CMK-3 (denoted as Pt@NCMK-3) was designed and fabricated to one-step eliminate Cr(VI) pollution at near neutral pH via simultaneous Cr(VI) reduction by catalytic hydrogenation and Cr(OH)3 recovery. Structural characterization showed that Pt particles of Pt@NCMK-3 were effectively embedded in the carbon rods of NCMK-3. Batch experiments revealed that Pt@NCMK-3 exhibited a higher catalytic activity and stability than other test catalysts. Fixed-bed column reaction results indicated that under the experimental conditions Pt@NCMK-3 had better breakthrough performances than other catalysts. Additionally, after 4 treatment-recovery cycles Pt@NCMK-3 maintained nearly identical breakthrough performance, whereas other catalysts displayed markedly decreased breakthrough bed volumes, reflecting a substantially higher stability of Pt@NCMK-3.

Fabrication of Mesoporous Carbon CMK-3 Modified Co0.9Cu0.1Si Alloy for Electrochemical Hydrogen Storage

Mechanical alloying is used to prepare the Co[Formula: see text]Cu[Formula: see text]Si alloy. Mesoporous silicon SBA-15 is employed as the template to synthesize mesoporous carbon CMK-3. For the purpose of improving the electrochemical properties of Co[Formula: see text]Cu[Formula: see text]Si alloy, Co[Formula: see text]Cu[Formula: see text] CMK-3 ([Formula: see text], 6%, 9% and 12% mass fraction) alloys are fabricated via ball-milling. As the negative electrodes of Ni–MH batteries, the discharge capacities of alloys are tested by the LAND CT2001A tester and three-electrode system. Finally, the composite alloys show different properties for hydrogen storage. A maximum discharge capacity (558.7[Formula: see text]mAh/g) is achieved for Co[Formula: see text]Cu[Formula: see text] CMK-3 electrode. Superfluous CMK-3 is not beneficial to enhance the discharge capacity of Co[Formula: see text]Cu[Formula: see text]Si alloy. Moreover, Co[Formula: see text]Cu[Formula: see text] CMK-3 electrodes exhibit better corrosion and oxidation resistance, which leads to higher capacity retention for CMK-3/Co[Formula: see text]Cu[Formula: see text]Si composites. The comparative studies on HRD and kinetic properties of Co[Formula: see text]Cu[Formula: see text]Si and Co[Formula: see text]Cu[Formula: see text] CMK-3 are also conducted. The [Formula: see text] of Co[Formula: see text]Cu[Formula: see text]Si alloy reduces and [Formula: see text] increases after doping of CMK-3. The special structural characteristics and higher conductivity of CMK-3 can offer more electrochemical active sites and accelerate hydrogen diffusion. Accordingly, the electrochemical activity and kinetic properties are enhanced for CMK-3/Co[Formula: see text]Cu[Formula: see text]Si composites.

An ultrasensitive aptamer-antibody sandwich cortisol sensor for the noninvasive monitoring of stress state

Cortisol is a major glucocorticoid that can affect physiological activities in the human body. Besides, it is also a biomarker that can reflect the stress state of the body. Therefore, in order to monitor stress states in a sensitive and non-invasive manner, an ultra-sensitive aptamer-antibody sandwich sensor modified with multi-walled carbon nanotubes, ordered mesoporous carbon CMK-3, and silver nanoparticles (MWCNTs/CMK-3/AgNPs) was proposed for non-invasive detection of cortisol in human saliva. The MWCNTs/CMK-3/AgNPs nanocomposite was fixed on the surface of the glassy carbon electrodes (GCEs) as the material for the first round of signal amplification, and secondary signal amplification was realized by conjugating cortisol antibodies with gold nanoparticles (AuNPs). Finally, the aptamer-antibody sandwich pattern was used to specifically recognize and bind cortisol. The concentration response range for this aptamer-antibody sandwich sensor is 0.1 pg/mL-10 ng/mL, and the limit of detection (LOD) is 0.09 pg/mL. So far, the LOD of this sensor has been relatively low, showing its good sensitivity, selectivity, stability, and reproducibility. Furthermore, it has been successfully applied to detect cortisol in saliva samples to compare the stress states of postgraduates and undergraduates.