Latest ArticlesA novel BINOL-based fluorescence probe (S)-6 featuring a sodium sulfonate fragment at the 2′-position was designed and synthesized via simple synthetic procedures under mild reaction conditions. The water-soluble probe (S)-6 displays excellent enantioselective recognition toward 15 common amino acids, and it can be used for enantiomeric excess determination of amino acids. The fluorescence intensity of (S)-6 treated with amino acids reaches the maximum after standing for only 30 min at room temperature and remains stable in the following 5.5 h, which has great potential in the application of chiral fluorescence analysis due to its timeliness and outstanding fluorescent stability.
Electrode materials with strong desalting ability is an important research direction of capacitive deionization. In this study, HKUST-1 was successfully synthesized by the solvothermal method, and MOFs-derived porous carbon/Cu@Cu2O composites were prepared by simple pyrolysis as cathode materials for CDI. After high-temperature pyrolysis, the Cu+ site with unsaturated coordination is generated, and the structure changes from micropores to the coexistence of mesoporous and micropores. The complex pore structure is conducive to strengthening ion migration and diffusion. The results show that the porous carbon/Cu@Cu2O materials derived from MOFs depend on the pseudocapacitance behavior for capacitive deionization and desalination. At a voltage window of -1.2 V~1.2 V, a current density of 40 mA/g, and 5 mmol/L NaCl, the HDC-1100 exhibited the best desalting capacity of 30.9 mg/g. HDC-1100 also has good cycle stability. After 20 cycles of adsorption and desorption, the desalting capacity almost does not decrease. Therefore, MOFs derived porous carbon/Cu@Cu2O composites are expected to be an excellent choice for CDI cathode materials.
Ammonia borane (NH3BH3, AB) is an ideal raw material of hydrogen production with higher hydrogen storage capacity. In this paper, the catalytic processes of AB dehydrogenation were described from different ways, including thermal dehydrogenation, hydrolysis, methanolysis, photocatalysis and photo-piezoelectric synergy catalysis with experimental research and theoretical calculations. Catalyst models include bulk materials, two-dimensional materials, nanocluster particles and single/diatomic structures. Among them, the proportion of H2 released is different, and the reaction conditions are also different, which are suitable for different application scenarios. Through this review, we could have a preliminary comprehensive understanding of AB dehydrogenation reaction.
A new palladium-catalyzed annulative allylic alkylation (AAA) reaction of 2-(indol-2-yl)phenols with dual allylic electrophiles such as isobutylene dicarbonate and butene dicarbonate is described, leading to the regioselective synthesis of tetracyclic medium-sized cyclic ethers possessing a bridged aryl-indole scaffold, namely, benzo[2,3]oxocino[4,5-b]indoles and benzo[2,3]oxepino[4,5-b]indoles, in good to excellent yields. This protocol demonstrates a broad substrate scope, good compatibility with substituents and high regioselectivity, providing a catalytic and flexible method for creating bridged aryl-indole skeletons.
Direct synthesis of glycerol carbonate (GC) from CO2 and glycerol (a byproduct of biodiesel production) is a route to obtain a high-value chemical from waste and low-cost byproducts but has not yet industrialized due to the lack of efficient catalysts. Ceria (CeO2) exhibits the highest catalytic activity and GC selectivity among the heterogeneous catalysts studied so far. However, the mechanism of this reaction over CeO2 catalysts has not been studied in detail. Herein, we synthesized CeO2 nanocrystals with different morphologies as model catalysts that can predominantly expose {111}, {110}, and {100} facets, and their surface acid-base properties were characterized using high-sensitivity temperature-programmed desorption of NH3 and CO2 with quadrupole mass spectrometry as detector (NH3-TPD-QMS and CO2-TPD-QMS). We found that the catalytic performance (GC formation rate) is strictly linearly dependent on the density of basic sites, which is relevant to the adsorption and activation of CO2. In addition, to illustrate a more microscopic reaction mechanisms underlying the formation of GC from CO2 and glycerol on all three low-index surfaces (111), (110) and (100), we also performed comprehensive first principles calculations. A three-step Langmuir–Hinshelwood (LH) mechanism was identified in which the annulation reaction is the rate-limiting step. The CeO2 (111) surface exhibits the lowest overall activation energy, which agrees well with the catalytic performance that the CeO2 nano-octahedra, predominantly exposing {111} facets, have the highest GC formation rate. This work is the first to combine experiments on shaped CeO2 model catalysts with first-principles calculations to gain insight into the mechanism of direct synthesis of GC from CO2 and glycerol, and will aid in the development of catalysts with improved performance.
Rational design of heterogeneous catalysts with high activity and stability is crucial in peroxymonosulfate (PMS)-based oxidation treatment of wastewater. Herein, the graphite oxide-cobalt ferrite (GO-CoFe2O4) composite was constructed, and its morphological, component and structural characteristics were thoroughly examined, respectively. GO-CoFe2O4 obviously boosted PMS catalytic performance on di-n–butyl phthalate removal (DBP, RDBP = 90%, RTOC = 37%), which indicated by the first-order kinetic constant (kDBP = 0.060 min−1) being roughly 4 times than pure CoFe2O4 (kDBP = 0.015 min−1). The fabrication of GO-CoFe2O4 brought the favorable stability and repeatability up to six cycles. Moreover, the method of batch dosing catalyst was creatively proposed to improve the PMS utilization efficiency. The coupling of GO enhanced the dispersion of CoFe2O4 particles to obtain sufficient active sites, additionally, the plentiful C=O groups and free-flowing electrons on GO promoted GO-CoFe2O4 to coordinate a redox process during PMS activation. With the aid of theoretical calculations, GO-CoFe2O4 was revealed to exhibit a strong affinity toward PMS adsorption, where PMS spontaneously dissociated into sulfate radical (SO4•−), hydroxyl radical (•OH) and singlet oxygen (1O2), acting as the reactive oxygen species (ROSs). Electrons cycling between Co, Fe and O species ensured continuous ROSs generation and excellent catalytic performance.
Herein, we review the significant of ordered macroporous (OM) TiO2-based catalysts for boosting photocatalytic CO2 reduction. Based on the need to improve the three key factors of photogenerated charge separation efficiency, solar energy utilization and CO2 adsorption rate during the conversion of CO2 to H2O, we summarized five modification measures: including doping ions into OM TiO2, introducing second semiconductor coupling and noble metal nanoparticles for fabricating multiple Z-scheme heterojunctions, constructing hierarchical pore and carbon-loaded OM TiO2 materials, which effectively enhance the absorption rate of visible light, the separation rate of electrons-hole pairs and the selection of multiple active sites. The OM structured TiO2-based photocatalysts solve the single or multiple key factors for enhancing photocatalytic performances during CO2 conversion. The catalytic mechanism and pathways of OM structured TiO2-based photocatalysts for CO2 reduction are discussed and summarized. It provides new insights on the development of high-efficient catalyst for photocatalytic CO2 conversion to solar fuels.
Anode SnO2 in lithium-ion batteries suffers from volume expansion and agglomeration. Here, the SnO2 nanoparticles are hybrided with ZrO2 particles by the support of carbon nanotube networks. The obtained SnO2/C/ZrO2 composite shows improved electrochemical performances. Investigations reveal that the carbon nanotubes shorten the transmission path of electrons and Li+ ions. Ball milling with ZrO2 promotes the formation of nanosized SnO2 to weaken the internal strain change, being beneficial to buffering volume change during electrochemical cycling afterwards. High-resolution 6, 7Li NMR investigations indicate that conversion and alloying reactions are stepwise involved for SnO2/C/ZrO2 anode. The strategy of designing SnO2/C/ZrO2 composite from the morphology-controlled metal-organic frameworks for energy storage widens the possibility to fabricate promising materials with enhanced performances.
Three-dimensional (3D) histology has exhibited tremendous potential in fundamental research and clinical disease grading, but compatible labeling techniques are still lacking. Recently in Science Advances, Pac et al. report a new histological technique termed 3DNFC, which realizes 3D fluorescence imaging of thick tissues via citrate-based in situ fluorophore formation.
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