查看更多>>摘要：The merging of transition metal catalysis with electrochemistry has become a powerful tool for organic synthesis because catalysts can govern the reactivity and selectivity.However,coupling catalysts with alkyl radical species generated by anodic oxidation remains challenging because of electrode passivation,dimerization,and overoxidation.In this study,we developed convergent paired electrolysis for the cou-pling of nickel catalysts with alkyl radicals derived from photoinduced ligand-to-metal charge-transfer of cyclic alcohols and iron catalysts,providing a practical method for site-specific and remote arylation of ketones.The synergistic use of photocatalysis with convergent paired electrolysis can provide alternative avenues for metal-catalyzed radical coupling reactions.
查看更多>>摘要：There is usually a trade-off between high mechanical strength and dynamic self-healing because the mechanisms of these properties are mutually exclusive.Herein,we design and fabricate a fluorinated phenolic polyurethane(FPPU)elastomer based on octafluoro-4,4'-biphenol to overcome this challenge.This fluorine-based motif not only tunes interchain interactions through π-π stacking between aromatic rings and free-volume among polymer chains but also improves the reversibility of phenol-carbamate bonds via electron-withdrawing effect of fluorine atoms.The developed FPPU elastomer shows the high-est recorded puncture energy(648.0 mJ),high tensile strength(27.0 MPa),as well as excellent self-healing efficiency(92.3％),along with low surface energy(50.9 MJ m-2),notch-insensitivity,and repro-cessability compared with non-fluorinated counterpart biphenolic polyurethane(BPPU)elastomer.Taking advantage of the above-mentioned merits of FPPU elastomer,we prepare an anti-fouling tribo-electric nanogenerator(TENG)with a self-healable,and reprocessable elastic substrate.Benefiting from stronger electron affinity of fluorine atoms than hydrogen atoms,this electronic device exhibits ultrahigh peak open-circuit voltage of 302.3 V compared to the TENG fabricated from BPPU elastomer.Furthermore,a healable and stretchable conductive composite is prepared.This research provides a dis-tinct and general pathway toward constructing high-performance elastomers and will enable a series of new applications.
查看更多>>摘要：The efficiency of rigid perovskite/silicon tandem solar cells has reached 33.9％.However,there has been no report on flexible perovskite/silicon tandem solar cells due to the challenge of overcoming the poor light absorption of ultrathin silicon bottom cells while maintaining their mechanical flexibility.Herein,we report the first demonstration of the perovskite/silicon tandem solar cell based on flexible ultrathin silicon.We show that reducing the wafer thicknesses and feature sizes of the light-trapping textures can significantly improve the flexibility of silicon without sacrificing light utilization.In addition,the cap-ping of the perovskite top cells can further improve the device's mechanical durability by shifting the neutral plane toward the silicon surface that is prone to fracture.Finally,the resulting ultrathin(～30 μm)flexible perovskite/silicon tandem solar cellachieves a certified stabilized efficiency of 22.8％with an extremely high power-to-weight ratio of 3.12 W g-1.Moreover,the flexible tandems exhibit remarkable bending durability,maintaining 98.2％of their initial performance after 3000 bending cycles at a radius of only 1 cm.
查看更多>>摘要：Orderly hierarchical structure with balanced mechanical,chemical,and electrical properties is the basis of the natural bone microenvironment.Inspired by nature,we developed a piezocatalytically-induced controlled mineralization strategy using piezoelectric polymer poly-L-lactic acid(PLLA)fibers with ordered micro-nano structures to prepare biomimetic tissue engineering scaffolds with a bone-like microenvironment(pcm-PLLA),in which PLLA-mediated piezoelectric catalysis promoted the in-situ polymerization of dopamine and subsequently regulated the controllable growth of hydroxyapatite crys-tals on the fiber surface.PLLA fibers,as analogs of mineralized collagen fibers,were arranged in an ori-ented manner,and ultimately formed a bone-like interconnected pore structure;in addition,they also provided bone-like piezoelectric properties.The uniformly sized HA nanocrystals formed by controlled mineralization provided a bone-like mechanical strength and chemical environment.The pcm-PLLA scaf-fold could rapidly recruit endogenous stem cells,and promote their osteogenic differentiation by activat-ing cell membrane calcium channels and PI3K signaling pathways through ultrasound-responsive piezoelectric signals.In addition,the scaffold also provided a suitable microenvironment to promote macrophage M2 polarization and angiogenesis,thereby enhancing bone regeneration in skull defects of rats.The proposed piezocatalytically-induced controllable mineralization strategy provides a new idea for the development of tissue engineering scaffolds that can be implemented for multimodal physical stimulation therapy.
NETL
NSTL
万方数据