The enhancement of chemi-, electrochemi-, and photo-luminescence in a corannulene dialkyl borate has been successfully achieved for the first time through the incorporation of an azabora-helicene, slowing down the bowl inversion of the molecule.
Photoelectrochemical (PEC) water splitting using semiconductors has become a promising strategy for clean and environmentally friendly solar fuel production. However, the efficiency of PEC water splitting is limited by the narrow optical absorption range, serious recombination of photogenerated charges and low quantum efficiency of semiconductors. Here we constructed a plasmonic photoelectrode by depositing Au nanoparticles (NPs) and Au nanorods (NRs) on the surface of three-dimensional (3D) branched TiO2 nanorod arrays. Experimental data indicate that the light absorption harvesting ability effectively enhanced in both ultraviolet and visible region by manipulating the shape of deposited Au nanostructure. Significantly, the photoconversion efficiency of Au NPs and Au NRs decorated 3D branched TiO2 photoanode increased by 2.6 times, compared with the pristine branched TiO2 nanorod arrays. Moreover, the plasmonic-enhanced PEC performance mechanism for water splitting is also discussed in this work.
Targeting sustainable and eco-friendly polymer synthesis, we demonstrate here a synergistically catalyzed atom transfer radical polymerization (ATRP) induced and controlled by interplay between ball milling (BM) and piezoelectric nanoparticles (piezoNPs). BM-induced electron transfer can be achieved through piezoNPs deformation under impact force, serving as an external stimulus to mediate polymerization. The ppm level of copper loading is sufficient in fabrication of a polymer with well-defined molecular weight and low polydispersity. High-molecular-weight polymers ranging from 33 to 74 kDa were prepared successfully through DMSO-assisted grinding. Besides, its good performance on availability of water as liquid-assisted grinding additive, the recyclability of piezoNPs, and the formation of cross-linker-free composite resin make our ATRP approach a green and practical option alongside the existent heat-, electro-, and photo-induced methods.
Silver nanomaterials have attracted a great deal of interest due to their broad-spectrum antimicrobial activity. However, it is still challenging to balance the high antibacterial efficiency with low damage to biological cells of silver nanostructures, especially when the diameter decreases to less than 10 nm. Here, we developed a new type of Ag nanohybrid material via a unimolecular micelle template method, which presents amazing antibacterial activities and almost noncytotoxicity. First, water-soluble multiarm star-shaped brushlike copolymer α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 was precisely synthesized and its micelle behavior in different solvents was revealed. Then, nanocrystal clusters assembled by Ag grains (Ag@Template NCs) were prepared through an in situ redox route using the unimolecular micelle of α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 as the soft template, AgNO3 as a precursor, and tetrabutylammonium borohydride (TBAB) as the reducing agent. The overall size of the achieved Ag@Template NCs is controlled by the template structure at around 40 nm (Dh in DMF), and the size of the Ag grain can be easily regulated from ∼1 to ∼5 nm by adjusting the feeding ratio of AgNO3/acrylic acid (AA) units in the template from 1:10 to 1:1. Benefitting from the structural design of the template, all Ag@Template NCs prepared here exhibit excellent dispersibility and chemical stability in different aqueous environments (neutral, pH = 5.5, and 0.9% NaCl physiological saline solution), which play a crucial role in the long-term storage and potential application in a complex physiological environment. The antibacterial and cytotoxicity tests indicate that Ag@Template NCs display much better performance than Ag nanoparticles (Ag NPs), which have a comparable overall size of ∼25 nm. The inhibitory capability of Ag@Template NCs to bacteria strongly depends on the grain size. Specifically, the Ag@Template-1 NC assembled by the smallest grains (1.6 ± 0.3 nm) presents the best antibacterial activity. For E. coli (−), the MIC value is as low as 5 μg/mL (0.36 μg/mL of Ag), while for S. aureus (+), the value is around 10 μg/mL (0.72 μg/mL of Ag). The survival rate of L02 cells and lactate dehydrogenase assay together illustrate the low cytotoxicity possessed by the prepared Ag@Template NCs. Therefore, the proposed Ag@Template NC structure successfully resolves the high reactivity, instability, and fast oxidation issues of the ultrasmall Ag nanoparticles, and integrates high antibacterial efficiency and nontoxicity to biological cells into one platform, which implies its broad potential application in biomedicine.
A novel protocol for testing the durability of proton exchange membrane fuel cell (PEMFC) stacks is developed using real-world road load data obtained from automobiles equipped with a PEMFC system manufactured by Weichai Power Company Limited, and the predetermined methodology is carried out for a cumulative duration of 4750 hours. The empirical results obtained from the durability test reveal that the average cell voltages (ACV) at specific current of 21 A, 105 A, 175 A, and 290 A exhibit degradation rates of 2%, 3.3%, 3.9%, and 10.9%, correspondingly. Furthermore,the polarization curve test results demonstrate ACV decay rates of 2.2% and 6.9% at 21 A and 360 A, respectively. The output voltage decay increases and the consistency of cells diminishes as the current rises. In comparison to the initial stage of the durability test, there is a slight decline in cell consistency observed toward the conclusion. In addition, a sensitivity test of the operational conditions is conducted at the 50th and 500th cycles, respectively. The findings reveal that the sensitivity to the cell consistency and output voltage remains largely stable throughout the durability test, and this suggests that the stack does not exhibit any noticeable alterations in its physicochemical characteristics.
Abstract Fabrication of the metal nanoparticles decorated boron nitride nanosheets (BNNSs) is an effective method to reduce the interfacial thermal resistance between fillers and is beneficial to form thermally conductive pathways in the composite. However, due to the chemical inertness of BNNS, a large amount of metal nanoparticles is really difficult to be immobilized onto the surfaces of BNNS. To solve this problem, in this work, poly(4‐vinylpyridine) (P4VP), possessing lots of coordination sites with Au nanoparticles (AuNPs), is applied to modify the BNNS by the self‐initiated photografting and photopolymerization (SIPGP). Then, the heterostructured BNNS‐ g ‐P4VP‐AuNPs hybrid fillers are prepared through P4VP‐assisted metallization approach. Results demonstrate that a large amount of AuNPs with an average size of 3–5 nm is immobilized onto the surfaces of BNNS‐ g ‐P4VP successfully. Furthermore, the in‐plane thermal conductivity of the nanofibrillated cellulose (NFC)‐based composite film with 30 wt% BNNS‐ g ‐P4VP‐AuNPs can reach as high as 14.04 W m −1 K −1 , due to the enhanced interfacial thermal conduction. Therefore, the proposed modification method promises opportunities for the fabrication of high‐efficiency thermally conductive fillers and composites.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
