Tracking the Electrocatalytic Activity of a Single Palladium Nanoparticle for the Hydrogen Evolution Reaction

The nanoparticle-based electrocatalysts’ performance is directly related to their working conditions. In general, a number of nanoparticles are uncontrollably fixed on a millimetre-sized electrode for electrochemical measurements. However, it is hard to reveal the maximum electrocatalytic activity owing to the aggregation and detachment of nanoparticles on the electrode surface. To solve this problem, here, we take the hydrogen evolution reaction (HER) catalyzed by palladium nanoparticles (Pd NPs) as a model system to track the electrocatalytic activity of single Pd NPs by stochastic collision electrochemistry and ensemble electrochemistry, respectively. Compared with the nanoparticle fixed working condition, Pd NPs in the nanoparticle diffused working condition results in a 2–5 orders magnitude enhancement of electrocatalytic activity for HER at various bias potential. Stochastic collision electrochemistry with high temporal resolution gives further insights into the accurate study of NPs’ electrocatalytic performance, enabling to dramatically enhance electrocatalytic efficiency.     

IVDAS: an interactive visual design and analysis system for image data symmetry detection of CNN models

Journal of Visualization - Convolutional neural networks (CNNs) have achieved breakthrough performance in image recognition and classification. However, it is still a challenge for CNNs to classify...     

Demonstration of joule-level chirped pulse amplification based on tiled Ti:sapphire amplifier

A novel tiled Ti:sapphire(Ti:S)amplifier was experimentally demonstrated with>1 J amplified chirped pulse output.Two Ti:S crystals having dimensions of 14 mm×14 mm×25 mm were tiled as the gain medium in a four-pass amplifier.Maximum output energy of 1.18 J was obtained with 2.75 J pump energy.The energy conversion efficiency of the tiled Ti:S amplifier was comparable with a single Ti:S amplifier.The laser pulse having the maximum peak power of 28 TW was obtained after the compressor.Moreover,the influence of the beam gap on the far field was discussed.This novel tiled Ti:S amplifier technique can provide a potential way for 100 PW or EW lasers in the future.     

Morphology Engineering of Fullerene (C60) Microstructures Featuring Surface Cracks with Enhanced Photoluminescence and Microscopic Recognition Properties

Surface cracks could improve the optical and photoelectronic properties of crystalline materials as they increase specific surface area, but the controlled self-assembly of fullerene (C₆₀) molecules into micro-/nanostructures with surface cracks is still challenging. Herein, we report the morphology engineering of novel C₆₀ microstructures bearing surface cracks for the first time, selecting phenetole and propan-1-ol (NPA) as good and poor solvents, respectively. Our systematic investigations reveal that phenetole molecules initially participate in the formation of the ends of the C₆₀ microstructures, and then NPA molecules are involved in the gradual growth of the sidewalls of the microstructures. Therefore, the surface cracks of C₆₀ microstructures can be finely regulated by adjusting the addition of NPA and the crystallization time. Interestingly, the cracked C₆₀ microstructures show superior photoluminescence properties relative to the smooth microstructures due to the increased specific surface area. In addition, C₆₀ microstructures with wide cracks show preferential recognition of silica particles over C₆₀ particles owing to electrostatic interactions between the negatively charged C₆₀ microstructures and the positively charged silica microparticles. These C₆₀ crystals with surface cracks have potential applications from optoelectronics to biology.     

Directional synthesis of furfural compounds from holocellulose catalyzed by sulfamic acid

Cellulose - The coproduction of 5-hydroxymethylfurfural (5-HMF) and furfural (FUR) via the direct hydrolysis of holocellulose analogue composed of cellulose and hemicellulose was investigated. The...     

Mechanically strong and stiff supramolecular polymers enabled by fiber reinforced long-chain alkane matrix

Fiber-reinforced-concrete (FRC) mechanism refers short discrete fibers that are uniformly distributed and randomly oriented, which offers an effective way to improve the mechanical performance of concrete. In the design of supramolecular polymers, an analogous concept of FRC appears to have been considered very rarely-although fibrous structure has been frequently observed/generated during the supramolecular polymerization. In this work, we apply the alkane thermosets, octadecane (C₁₈H₃₈) and tetracosane (C₂₄H₅₀), taking the role of “concrete”, and the low-molecular-weight monomer with long alkyl chains as the essential “fiber” component, to fabricate the “fiber reinforced supramolecular polymer”. Very much like FRC mechanism in material science, the resulting fiber reinforced supramolecular polymer thus exhibit unusually high mechanical strength and stiffness, which is unprecedented in the conventional supramolecular strategy.     

Rh-Catalyzed Decarbonylative Cross-Coupling between o-Carboranes and Twisted Amides: A Regioselective,Additive-Free,and Concise Late-Stage Carboranylation

The convenient cross-coupling of sp² or sp³ carbons with a specific boron vertex on carborane cage represents significant synthetic values and insurmountable challenges. In this work, we report an Rh-catalyzed reaction between o-carborane and N-acyl-glutarimides to construct various B_cage−C bonds. Under the optimized condition, the removable imine directing group (DG) leads to B(3)− or B(3,6)−C couplings, while the pyridyl DG leads to B(3,5)−Ar coupling. In particular, an unexpected rearrangement of amide reagent is observed in pyridyl directed B(4)−C(sp³) formation. This scalable protocol has many advantages, including easy access, the use of cheap and widely available coupling agents, no requirement of an external ligand, base or oxidant, high efficiency, and a broad substrate scope. Leveraging the Rh^I dimer and twisted amides, this method enables straightforward access to diversely substituted and therapeutically important carborane derivatives at boron site, and provides a highly valuable vista for carborane-based drug screening.     

Selection of Planar Chiral Conformations between Pillar[5,6]arenes Induced by Amino Acid Derivatives in Aqueous Media

Chiral α-amino acids play critical roles in the metabolic process in nearly all life forms. So far, chiral recognition of α-amino acids has mainly focused on the determination of l /d enantiomers. Herein, selection of planar chiral conformations between water-soluble pillar[5]arene WP5 and pillar[6]arene WP6 was observed due to α-side chain or ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides binding with WP5 and WP6 , respectively. Therefore, α-side chain and ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides were recognized by observing the induced CD signal and its inversion. This is a rare example of being able to detect the chiral region around α-carbon of a chiral α-amino acid molecule.     

Aromatic Aza-Claisen Rearrangement of Arylpropargylammonium Salts Generated in situ from Arynes and Tertiary Propargylamines

The charge-accelerated aza-Claisen rearrangement of ammonium salts serves as a key step in the construction of complex nitrogen-containing molecules. However, much less attention has been paid to the aromatic aza-Claisen rearrangement than to the aliphatic one. Herein, we report an unprecedented aromatic aza-Claisen rearrangement of arylpropargylammonium salts, generated in situ from arynes and tertiary propargylamines, delivering structurally diverse 2-propargylanilines in moderate to good yields with high regioselectivity. This rearrangement proceeds in the absence of strong bases or transition metals, is compatible with moisture and air, tolerates a wide variety of functional groups, and is amenable to forming 11- to 13-membered heterocycles with a triple bond. The 2-propargylaniline products were treated with aluminum chloride in ethanol to afford multisubstituted indoles in moderate to excellent yields. Finally, a series of deuterium-labeling experiments was performed to elucidate the reaction mechanism.     

Polyoxometalate-Based Nanomaterials Toward Efficient Cancer Diagnosis and Therapy

As an emerging class of inorganic metal oxides, organically functionalized polyoxometalates (POMs) or POM-based nanohybrids have been demonstrated promising potential for the inhibition of various cancer types by the virtue of their diversity in structures and significantly reduced toxicity. This contribution summarizes the latest achievement of POM-based nanomaterials in cancer diagnosis and various therapeutics to put forward our fundamental viewpoints on the design principles of modified POMs based on their application. In addition, major challenges and perspectives in this field are also discussed. We expect that this review will provide a valuable and systematic reference for the further development of POM-based nanomaterials.