Latest ArticlesThe transformation of quantum dots (QDs) by organisms has attracted broad attention but remains unclear. Understanding of the metabolites helps to reveal the transformation pathway of QDs. Cd containing-metallothionein (MT) are the main species formed by Cd released from CdSe QDs in HepG2 cells, while speciation analysis of Cd containing MTs remains a challenge because MTs has several subisoforms and can bind with several metals. Herein, we built a hyphenated platform for speciation analysis of QDs in HepG2 cells after treatment with CdSe/ZnS QDs. The Cd-containing MTs were separated in reversed phase high performance liquid chromatography (RP-HPLC) and subsequently online detected by inductively coupled plasma mass spectrometry (ICP-MS) and electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS) parallelly. Four groups of Cd-containing metabolites were found by detecting Cd in ICP-MS. Their structures were identified in ESI-Q-TOF-MS and further confirmed with standards of four subisoforms of MT, including N-terminal acetylation MT2a, N-terminal acetylation MT1e, N-terminal acetylation MT1g and MT1m. Each group of them contains various stoichiometry of Cd/Zn. The metabolites of QDs remain same while the concentrations of each metabolite and its stoichiometry of Cd/Zn vary for different incubation concentration/time. This work provides a new parallel hyphenation technique of HPLC-ICP-MS/ESI-MS with high separation resolution and powerful detection ability, and the obtained results provide detailed metabolism information of QDs in HepG2 cells after treatment of CdSe/ZnS QDs, contributing to deep exploration of the functional mechanisms of QDs in organisms.
Heterogeneous catalysis is a vivid branch of traditional catalysis field, with the advantage of high efficiency and being easily separated from reactants and products after reaction, and have received widespread attentions in large-scale industrial production, especially in the field of energy utilization. Boron has been found to be a key functional component for designing high-performance heterogeneous catalysts. In this review, we cover and categorize the past and recent progress in boron-containing materials and their applications in heterogeneous catalysis particularly in energy‐related fields. The fundamental roles of boron components in the emerging heterogeneous catalysis of construction, regulation and stabilization of active phases/sites are highlighted, with the emphasis on how they regulating structural and electronic properties of host materials. We then categorize boron-containing catalysts into six kinds mainly including intermetallic boride catalysts, metal boride-derived catalysts, boron-doped catalysts, metal boride-decorated catalysts, boron-containing compounds as catalyst supports, and single-boron-site catalysts, as well as try to establish structure-catalytic activity relationship. The catalytic applications of these six boron-containing catalysts are discussed separately, focusing on the energy-related reactions such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR) and nitrogen reduction reaction (NRR). Finally, the opportunities and challenges related to boron-containing compounds in the field of catalysis are prospected.
Efficient CO2 reduction reaction (CO2RR) is one of the important topics in energy and environment field, but improving the electrochemical selectivity of specific product is a great challenge. Herein, we reported a unprecedented two-dimensional (2D) metal−organic framework with CuO4 unit (denoted as Cu-HHTT, HHTT = 9, 10-dihydro-9, 10-[1,2]benzenoanthracene-2, 3, 6, 7, 14, 15-hexaol) as the electrocatalyst for CO2RR. Cu-HHTT exhibits high performance for CO2RR to produce CO, namely Faradaic efficiency of 96.6% toward CO with a current density of 18 mA/cm2 at the potential of −0.6 V vs. RHE. Density function theory reveals that the desorption of CO species exhibits a lower energy barrier than that of hydrogenation of *CO intermediate, resulting in CO as the main product instead of alcohols or hydrocarbons.
Solid-state materials that exhibit pressure stimulus-response characteristics in a manner of emission signal, known as piezochromic luminescence (PCL), demonstrate great potential in photoelectric devices. The weakened luminescence and insignificant color change in the aggregation state, however, hampers their practical applications. Herein, a highly emissive coordination polymer, [Zn2(H4TTPE)(H2O)4].H2O (CUST-805), is successfully constructed by employing an AIE-active chromophore as the building block. The structural characterization and photophysical properties are systematically studied. Owing to intrinsic twisted conformation and AIE feature of tetraphenylethylene-tetrazole ligand, CUST-805 achieves the visible and reversible PCL from blue to green switched by different external stimuli. The transformation between crystalline and amorphous states is proved to be the origin of present PCL behavior. Moreover, on basis of electron and energy transfer quenching mechanism, the highly selective and sensitive sensor based on CUST-805 is realized, showing the low detection limit of 0.29 ppm towards 2, 4, 6-trinitrophenol.
The production of CH3COOH from CO2 and CH4 has stimulated much interest due to the high energy density of C2 species. Various kinds of catalysts have been developed while the high dissociation barrier of CH4 and low selectivity still hinders the efficiency of the reaction. We have herein proposed a novel catalyst with single metals loaded on 2D BC3N2 substrate (M@2D-BC3N2) based on density functional theory. Among numerous candidates, Pt@2D-BC3N2 possesses the most favorable reactivity with an ultralow barrier of CH4 splitting (0.26 eV), which is due to the efficient capture ability of CH4 on Pt site. Besides, the selectivity for CH3COOH is also very high, which mainly stems from the unique electronic properties of molecules and substrate: The degenerated states, including s, px, py and pz, in CO2 reflects the existence of delocalized π bonds between C and O. This can interact with states of Pt(s), Pt(pz), Pt(dxz), Pt(dyz), and Pt(z2) in Pt@2D-BC3N2. The kinetics model also proves that our system can promote CH3COOH production via simply increasing the temperature or the coverage of CH4 and CO2. Our results provide a reasonable illustration in clarifying mechanism and propose promising candidates with high reactivity for further study.
The defect engineering in graphene plays a significant role for the application of gas sensors. In this work, we proposed an efficient method to prepare ultrasensitive gas sensors based on the porous reduced graphene oxide (PRGO). Photo-Fenton etching was carried out on GO nanosheets in a controlled manner to enrich their vacancy defects. The resulting porous graphene oxide (PGO) was then drop-coated on interdigital electrodes and hydrothermal reduced at 180 ℃. Controllable reduction was achieved by varying the water amount. The gas sensor based on PRGO-5 min-6 h exhibited superior sensing and selective performance toward nitrogen dioxide (NO2), with an exceptional high sensitivity up to 12 ppm−1. The theoretical limit of detection is down to 0.66 ppb. The excellent performance could be mainly attributed to the typical vacancy defects of PRGO. Some residue carboxylic groups on the edges could also facilitate the adsorption of polar molecules. The process has a great potential for scalable fabrication of high-performance NO2 gas sensors.
Supercapacitors (SCs) are rated as the foremost efficient devices bridging the production and consumption of renewable energy. To address the ever-increasing energy requirements, it is indispensable to further develop high-performance SCs with merits of high energy-density, acceptable price and long-term stability. This review highlights the recent advances on halogen-based functionalized chemistry engineering in the state-of-the-art electrode system for high-performance SCs, primarily referring to the doping and decoration strategies of F, Cl, Br and I elements. Due to the discrepancy of electronegativity and atomic radius, the functionalization of each halogen element endows the substrate materials with different physicochemical properties, including energy bandgap structure, porosity distribution and surface affinity. The principle of halogen embedment into host materials by precisely controlling ionic adsorption and electronic structure is presented. And, the vital perspectives on the future challenges of halogen functionalization are also discussed. This work aims to deepen the understanding of halogen-based functionalized strategies to motivate further research for the development of high-performance SCs, and it also provides a prospect for exploring new material modification methods for electrochemical energy storage.
NH3 plays an essential role in human life since it is an important raw material for fertilizers, plastics and rubbers production. As an NH3 synthesis technology under ambient conditions, electrocatalytic N2 reduction reaction (NRR) has great potential to replace the energy-intensive Haber-Bosch process. The key of electrocatalytic NRR is the exploration of efficient catalysts. Transition metal Mo is promising since it exists naturally in nitrogenase due to the unique Mo-N2 interaction; particularly in the form of 2D material such as MoSe2, the surface area is maximized for more active sites. However, the NRR performance of MoSe2 is still unsatisfactory because Mo is only exposed at the semi-open edge, and the electronegative Se-mantled surface area remains inaccessible to N2. Herein, we propose a simple and effective strategy to create high-concentration Se vacancies in MoSe2 through heteroatom doping induced lattice strain, which effectively enhances the Mo-N2 interaction on the surface area. In result, high NH3 yield (3.04 × 10–10 mol s–1 cm–2) and Faraday efficiency (21.61%) are attained at –0.45 V vs. RHE in 0.1 mol/L Na2SO4.
Supramolecular chemistry has received considerable attention in host-guest recognition. The structure-response relationship of host-guest recognition system is a meaningful issue. Herein, a series of tripodal nitrogen mustard derivatives (TMs) have been developed in this paper. By rationally design the intramolecular alkyl chain lengths of host, the host-guest binding model have been successfully tuned, which underwent a transformation from π-π to multiple hydrogen bonds. This process enhances the host-guest binding force and recognition efficiency.
The cycloaddition reactions of methane and ethylene mediated by Ir+ have been designed and studied by the techniques of mass spectrometry in conjunction with theoretical calculations. Studies have shown that Ir+ can mediate the cycloaddition reaction of CH4 and two C2H4 to generate a half-sandwich structure IrHCp+ (Cp = η5-C5H5) including pentamethylcyclopentadienyl ligand by continuous dehydrogenation reaction with the forming of three C-C bonds and seven C-H bonds. The orbital analysis indicates the mechanism of the cyclization reaction to generation of pentamethylcyclopentadienyl ligand with odd number carbon atom depends on the overlap of π orbitals in -C2H2 and carbene, which is more difficult than the forming of cyclobutadiene ligand and benzene. This study may help to understand the reaction mechanism in the cycloaddition reactions of organic compounds, which will be useful to guide the rational design of new catalysts with tailored selectivity and increased efficiency.
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