Latest ArticlesUpconversion (UC) technology makes it possible to harvest infrared (IR) light from the sun and has increasingly been employed in recent years to improve the efficiency of solar cells. The progress in the area concerns both research on fundamental principles and processes of UC and technologies of device fabrication. Significant increase of important solar cell parameters, like short-circuit photocurrent density and open-circuit photovoltage as well as the total photon-to-current efficiency, has been accomplished. We here review the research published during the last few years in the area, in particular we consider the two most cherished techniques, namely the incorporation of upconverting nanophosphors directly into the photoanodes of the solar cells and the introduction of plasmonic metal nanoparticles co-existing with the UC particles. Other ways to achieve strong field enhancement, and the use of the non-linear nature of UC, is to apply microlenses, with or without assisting plasmonic excitation. Further enhanced UC action has been demonstrated by broad band and effective harvesting by organic IR antennas, with subsequent mediation by an intermediate nanoshell of the energy into the upconverting core. Codoping, nanohybrid and layer-by-layer technologies involving upconverting particles as well as the use of upconverting nanoparticles in hole-transport and electrolyte layers, tested in recent works, are also reviewed. While most of these technologies employ upconverting rare earth metals for sequential photon absorption, the main alternative technique, namely triplet-triplet annihilation UC using organic materials, is also reviewed. It is our belief that all these approaches will be further much researched in the near future, with potentially great impact on solar cell technology.
Methane (CH4) controllable activation is the key process for CH4 upgrading, which is sensitive to the surface oxygen species. The high thermal conductivity and superb thermal stability of the hexagonal boron nitride (h-BN) sheet makes a single transition metal atom doped hexagonal boron nitride monolayer (TM-BN) possible to be a promising material for catalyzing methane partial oxidation. The performances of 24 TM-BNs for CH4 activation are systematically investigated during the CH4 oxidation by means of first-principles computation. The calculation results unravel the periodic variation trends for the stability of TM-BN, the adsorption strength and the kind of O2 species, and the resulting CH4 activation performance on TM-BNs. The formed peroxide O22- of which the O—O bond could be broken and O- anions are found to be reactive oxygen species for CH4 activation under the mild conditions. It is found that the redox potential of TM center, including its valence electron number, coordination environment, and the work function of TM-BN, is the underlying reason for the formation of different oxygen species and the resulting activity for CH4 oxidative dehydrogenation.
Photocatalytic water splitting utilizing solar energy is considered as one of the most ideal strategies for solving the energy and environmental issues. Recently, two-dimensional (2D) materials with an intrinsic dipole show great chance to achieve excellent photocatalytic performance. In this work, blue-phase monolayer carbon monochalcogenides (CX, X = S, Se) are constructed and systematically studied as photocatalysts for water splitting by performing first-principles calculations based on density functional theory. After confirming the great dynamical, thermal, and mechanical stability of CX monolayers, we observe that they possess moderate band gaps (2.41 eV for CS and 2.46 eV for CSe) and high carrier mobility (3.23 × 104 cm2 V-1 s-1 for CS and 4.27 × 103 cm2 V-1 s-1 for CSe), comparable to those of many recently reported 2D photocatalysts. Moreover, these two monolayer materials are found to have large intrinsic dipole (0.43 D for CS and 0.51 D for CSe), thus the build-in internal electric field can be selfintroduced, which can effectively drive the separation of photongenerated carriers. More importantly, the well-aligned band edge as well as rather pronounced optical absorption in the visible-light and ultraviolet regions further ensure that our proposed CX monolayers can be used as high efficient photocatalysts for water splitting. Additionally, the effects of external strain on the electronic, optical and photocatalytic properties of CX monolayers are also evaluated. These theoretical predictions will stimulate further work to open up the energy-related applications of CX monolayers.
A novel diselenide-containing crown ether (BC7Se2) was fabricated, which can polymerize to form cyclic oligomers through intermolecular dynamic covalent reaction by irradiation of visible light. The size and distribution of oligomers are related to the monomer concentration. The decomposition reaction of oligomers is controlled by topology and solvents. Furthermore, potassium cation can inhibit the polymerization of BC7Se2 and accelerate the decomposition of oligomers.
A novel photoenzyme-coupled artificial catalytic system is fabricated by immobilizing horseradish peroxidase (HRP) on the Bi2WO6 hollow nanospheres via a facile electrostatic self-assembly process. The obtained Bi2WO6/HRP sample not only improves the visible light harvest ability but also promotes the high-efficiency separation of charge carriers. More importantly, the photogenerated electrons and produced H2O2 on Bi2WO6 directly take part in redox cycle reactions of HRP to induce photoenzyme synergic catalytic effect. In consequence, the degradation activity of Bi2WO6/HRP is significantly improved relative to Bi2WO6 and HRP for removing bisphenol A (BPA) under the visible light irradiation. This work launches a feasible design strategy for exploiting photoenzyme-coupled artificial catalytic system with special structure to degrade organic pollutants in water efficiently.
Aqueous electrolytes are safe, economic, and environmentally friendly. However, they have a narrow potential window. On the other hand, organic electrolytes exhibit good thermodynamic stability but are inflammable and moisture sensitive. In this study, we prepared water-PEG-lipid ternary electrolytes (TEs). To combine the advantages of water, polyethylene glycol (PEG) and propylene carbonate (PC). The nonflammable mixed electrolytes exhibited a wide potential window of about 2.8 V due to the beneficial effects of PEG and PC. Using these TEs, a lithium manganate–active carbon ion capacitor could be operated at 2.4 V with an energy density of 32 Wh/kg, based on the total active electrode material (current density of 3.3 mA/cm2). This value was significantly higher than that achieved using an aqueous electrolyte, thereby rationalizing the higher energy density.
Rhodium(Ⅲ)-catalyzed [4 + 1] cyclization of azobenzenes with α-Cl ketones has been developed. 3-Acyl-2H-indazoles could be easily afforded in up to 97% yields for more than 30 examples. The obtained products are potentially valuable in organic synthesis and drug discovery. This protocol featured with high efficiency, extensive functional group tolerance and mild reaction conditions. The one-step efficient construction of an anti-inflammatory agent confirms the practicability of this procedure.
Tyrosinase (TYR) is an important polyphenolic oxidase enzyme and usually regards as a biomarker of melanoma cancer. Highly effective tracking TYR activity in vivo will help to study the mechanism of TYR in living organisms and forecasts related diseases. In this study, we present a novel TYR-activatable fluorescent probe (CHMC-DOPA) for tracking TYR activity in vitro and in vivo. CHMC-DOPA is constructed by incorporating dopamine (DOPA) moiety into a fluorescent chloro-hydroxyl-merocyanine (CHMC) scaffold. Upon exposure to TYR, the dopamine unit in CHMC-DOPA is oxidized to a dopaquinone derivative, and an intramolecular photo-induced electron transfer (PET) process between CHMC fluorophore and o-dopaquinone will take place, the fluorescence of CHMC-DOPA is quenched rapidly. Therefore, the evaluation of TYR activity is established in terms of the relationship between fluorescence quenching efficiency and TYR activity. In our experiments, CHMC-DOPA shows various advantages, such as fast response (8 min), low concentration of TYR activation (0.5 U/mL), good water-solubility, as well as the lowest detection limit (0.003 U/mL) compared with previously reported works. Furthermore, CHMC-DOPA also exhibits excellent cell membrane permeability and low cytotoxicity, which is successfully used to monitor endogenous TYR activity in living cancer cells and zebrafish models. CHMC-DOPA performs well, and we anticipate that this newly designed novel platform will provide an alternative for high effective monitoring TYR activity in biosystems.
Polypeptoids have been explored as mimics of polypeptides, owing to polypeptoids' superior stability upon proteolysis. Polypeptoids can be synthesized from one-pot ring-opening polymerization of amino acid N-substituted N-carboxyanhydrides (NNCAs). However, the speed of polymerization of NNCAs can be very slow, especially for NNCAs bearing a bulky N-substitution group. This hindered the exploration on polypeptoids with more diverse structures and functions. Therefore, it is in great need to develop advanced strategies that can accelerate the polymerization on inactive NNCAs. Hereby, we report that lithium/sodium/potassium hexamethyldisilazide (Li/Na/KHMDS) initiates a substantially faster poly-merization on NNCAs than do commonly used amine initiators, especially for NNCAs with bulky N-substitution group. This fast NNCA polymerization will increase the structure diversity and application of polypeptoids as synthetic mimics of polypeptides.
Traditional colorimetric glucose biosensor generally involves complex assay procedures. Free labile enzymes and peroxidase substrates are used separately for triggering a chromogenic reaction. These limits result in inferior enzyme stability and defective enzymatic catalytic efficiency, making it hard to routinely utilize them for the direct and fast test of glucose. In this work, we provide an all-inclusive substrates/enzymes nanoparticle employed 3, 3'5, 5'-tetramethylbenzidine (TMB) as chromogenic substrates and glucose oxidase (GOx)/horseradish peroxidase (HRP) as signal amplifier enzymes (TMB-GH NPs) by the molecule self-assembly technique. The "all-inclusive" nanoparticles can realize the tandem colorimetric reactions, and the oxidation product of TMB (ox-TMB) exhibits a strong NIR laser-driven photothermal effect, thus allowing quantitative photothermal detection of glucose. Owing to the restriction of the molecular motion of GOx, HRP, and TMB, the distance of mass transfer between substrates was shortened largely, leading to improved catalytic activity for glucose. Overall, our strategy will simplify the analysis procedure, furthermore, these integrated nanoparticles not only display higher stability and activity than that of the free GOx/HRP system and possesses an excellent performance for colorimetric and photothermal bioassay of glucose simultaneously. We believe that this unique technique will give good inspirations to develop simple and precise methods for bioassay.
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