查看更多>>摘要：Efficient and selective electrocatalysts materials are currently needed for renewable energy conversion. This work studies the influence of internal channel modifications and the type of mesoporous silica that changes the electrocatalytic activities from the synthesized mesoporous carbon. Thus, MCM-41 and SBA-15 functionalized with amine (A) or diamine (D) groups and polyaniline (PANI) after pyrolysis produces derived mesoporous heteroatom-doped carbon that were evaluated as electrocatalyst in oxygen reduction reaction (ORR) for fuel cell systems. ORR can produce two types of products, allowing us to differentiate the main electrocatalytic activities of the synthesized mesoporous carbons. Therefore, the electrocatalytic results correlated the number of electrons transferred with the kind of ORR product generated. CS41/D/PANI, mesoporous carbon obtained from MCM-41 modified with diamine groups, was selective towards the production of H2O2 with 2.6 electrons transferred during the reaction while the CS41/A/PANI, mesoporous carbon obtained from MCM-41 modified with amine groups, presented high catalytic activity compared to Pt/C, leading to complete reduction of O-2 to H2O. However, SBA-15 does not generate mesoporous carbons with selectivity for ORR. Then, this result is directly correlated with the influence that the mesoporous carbon suffered by the silica pore size and initial modification with amine or diamine groups. Finally, the chronoamperometry analysis demonstrated carbon materials with stability over a long period and high methanol tolerance compared with noble metals like Pt/C catalysts.
查看更多>>摘要：As electrode for lithium ion batteries (LIBs), Coordination polymers (CPs) have exhibited considerable potential. However, due to the unsatisfactory cycling and rate performance, their practical application often encounters obstacles. This work reports Fe-based coordination polymers with improved lithium storage performance induced by cobalt ions for the first time. The introduction of cobalt ions is confirmed to obviously increase the active sites and conductivity for the electrode. When used as anode of LIBs, the unique Fe-Co-BDC pencil-like polyhedron exhibits a large reversible capacity of 1188 mAh g-1 at 100 mA g-1 after 300 cycles and also shows a good cycling life at the large currents. The lithium storage mechanism of Fe-Co-BDC is demonstrated to be associated with carboxylate groups and benzene rings of the organic ligands during lithiation and delithiation based on the ex situ FTIR and XPS spectra.
查看更多>>摘要：The nanosheet SAPO-34 zeolite crystals with a diameter of 300 nm and a thickness of 50 nm using a new phosphorus source (pyrophosphoric acid, H4P2O7) were synthesized. The roles of the pyrophosphate (P2O74 ) species in the crystallization of SAPO-34 were elucidated. The results suggested that one P atom from the P2O74-species participated in the formation of the CHA framework structure while the other P atom served as a crystallization control agent, facilitating preferential crystal growth in [100] crystal plane. The SAPO-34 nanosheets have silica-rich shell and phosphorus-rich core leading to superior catalytic performance in methanol-to-olefin reaction (MTO). The catalytic lifetime of the SAPO-34 nanosheets was significantly improved due to the larger amount of medium-strong surface acidity and short diffusion pathway in comparison to the conventional SAPO-34 catalyst synthesized in the presence of the classical phosphorus source (H3PO4).
查看更多>>摘要：Enhancing catalytic activity and stability of supported Lewis acid catalysts remain a particular challenge owing to the limited understanding and unsatisfactory tuning of the interplay between the active components and the supports. Herein, upon immobilizing AlCl3 on a series of ternary metal oxides including La2O3-Al2O3-SiO2, NiO-Al2O3-SiO2 and Ga2O3-Al2O3-SiO2, we clearly revealed the influence of the compositions and structures of the supports on the catalyst performances through experiments together with density functional theory (DFT) calculations. The catalytic performances of the supported samples were evaluated by oligomerization of 1-decene using both batch reactor and fixed-bed apparatus. The results suggest that the AlCl3 supported by NiO-Al2O3-SiO2 composites exhibits the highest catalytic activity and stability because of its positive pore structure and thereof the high loading of active species. Importantly, DFT calculations indicate that the variations of the host-guest interaction energy between the ternary oxide composites and AlCl3 are in good agreement with the experimental results. This study highlights the compositions and structures of the supports are crucial to the catalytic performances of Lewis acid catalysts, and provides fundamental guidance for design of high-performance supported catalysts.
查看更多>>摘要：In this article, we have demonstrated an effective strategy to detect and remove the toxic Hg2+ by an ion-selective optical sensor using chromoionophoric receptor that is homogenously dispersed onto the surface of porous organic polymer (POP) template. Herein, we present a detailed summation of the synthesis of different POPs by employing various kinds of monomers and crosslinkers to discover excellent structural property materials that could cater to the needs of an optical sensor. The resultant POP from the bulk polymerization of N,N-dimethyl allylamine (DMA), and trimethylolpropane triacrylate (TMPTA), i.e., poly(DMA-co-TMPTA), manifested a higher surface area with pore size, thus has been utilized as the substrate material for the fabrication of the sensor. Further, the chromoionophoric coordinating ligand, i.e., 7-4(diethylamino)phenyldiazenyl quinolin-8-ol (DPDQ), is immobilized as receptor molecules onto the POP template for ultra-trace detection of Hg2+. The surface dispersed receptor forms stable 1:1 charge-transfer complexes [Hg2+-DPDQ] with a striking naked-eye color transition from pale orange to bright reddish-brown. The developed optical sensor offers an ultra-fast, selective response for Hg2+ with a lower detection limit of 0.1 mu g/L (ppb) in the linear range of 0-100 mu g/L. The regeneration of the sensor is envisaged with 0.02 M HCl and can be reused for up to six sensing cycles. Actual water samples from different geographical locations of India are tested using the developed sensor, and the method proved effective for real-time monitoring of Hg2+.
查看更多>>摘要：Calcium carbonate nanoparticles of 50 nm in diameter are synthesized within the mesoporous silica particles with a subsequent etching out of the template material. Due to interaction of the filler with a template the as prepared CaCO3 nanoparticles are doped with Si which allows preserving their small size and porous structure. To make an aggregatively stable aqueous suspension of the nanoparticles they are additionally doped with Fe. The obtained CaCO3:Si:Fe nanoparticles possess a micro-mesoporous structure with specific surface area of 205 m(2) g(-1) and pore volume of 0.59 cm(3) g(-1). It is shown that the particles are fully dissolved in dilute HCl in several minutes. It is demonstrated that nanoparticles are nontoxic and are able to penetrate across the cell membrane and accumulate in HeLa and K-562 cells. Owing to high adsorption capacity a loading of 25 wt% doxorubicin (DOX) into CaCO3:Si:Fe nanopaticles is performed. Being internalized by cells DOX-loaded CaCO3: Si:Fe nanoparticles provide greater amount (up to three times) of DOX within the intracellular space compared to free doxorubicin. Encapsulation of the drug into the nanoparticles reduces its toxicity, IC50 value increases by 2.5 and 5 times for HeLa and K-562 cells, respectively.
查看更多>>摘要：Ordered mesoporous SiO2 samples (SBA-15) with different pore sizes were prepared as carriers, and a series of catalysts (CoOx@SBA-15(X)) were synthesized to confine CoOx in SBA-15 through the solid-state grinding method for CO oxidation. The characterization results showed that the aggregation of CoOx in the pores of the carrier SBA-15 was effectively inhibited by the confinement effect, which further facilitated the formation of the main catalytic site Co(III) species. The results of the density-functional theory calculations further confirmed that Co(III) was the important catalytic site for CO oxidation. Compared with the catalyst prepared through the impregnation method, catalysts CoOx@SBA-15(X) exhibited a lower CO conversion temperature and activation energy for CO oxidation. In addition, the pore size of the carrier SBA-15 had a significant impact on the catalytic activity of CoOx, and the catalyst prepared with a larger pore size SBA-15 as carrier exhibited a higher catalytic activity. This result was mainly attributed to the fact that the confinement effect could effectively enhance the defect formation in metal oxides. Furthermore, the catalyst with a larger pore size SBA-15 as a carrier presented a higher content of Co(III) species, which significantly enhanced the catalytic activity of CoOx for CO oxidation. The results demonstrated that the pore structure of SBA-15 could affect the formation of the metal oxide (CoOx) species, which further significantly affected the catalytic activity of CoOx for CO oxidation. The results are expected to provide a strategy to synthesize efficient catalysts for CO oxidation by using ordered mesoporous materials.
查看更多>>摘要：The current review aims to provide the readers with an updated and explanatory overview of the PBA and related materials and how their structural features make them suitable for various environmental applications. Here we review the relevant structural aspects of the cyanide coordination polymers, mainly PBA, the most studied subfamily up to date, to describe this family of compounds better. Their porous nature, large surface area, cavities, and tunable composition stand out as attractive properties of PBA or hybrid-PBA for water and air decontamination. The most distinguished physicochemical properties and how they determine the versatility and broad scope of applications for these materials are herein discussed. A section is dedicated to the different engineering strategies of PBA, where the synergy between the components enhances the properties and performance of the new materials. The use of these compounds in adsorption, ionic exchange, desalinization, and advanced oxidation processes is described based on the tight structure-properties-functionality relationship. Some final considerations on the future potentials and limitations of cyanide coordination polymers are given from the authors' point of view.
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