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A green process for the synthesis of supported Pd nanoparticles (NPs) using poplar leaf extract (PLE) as a reducing agent and the extracted residue of poplar leaf (RPL) as a carrier is reported. The Pd/RPL nanocomposites were characterized by XRD, TEM, SEM, EDS, XPS, FTIR, and ICP-AES. The spherical Pd NPs had a mean particle size of 3.1 nm and were evenly distributed on the RPL surface. More importantly, the Pd/RPL nanocomposites were used as a heterogeneous catalyst, which presented superior catalytic activity for the Suzuki coupling reaction. In addition, only a slight loss in the catalytic activity was observed after six recycles.

Background: Cyclocarya paliurus (Batal.) Iljinskaja is a common endemic tree species. The leaves of C. paliurus are used as a Chinese medicine and the main active components are polysaccharides. However, the temporal pattern of polysaccharide synthesis at different leaf developmental stages has not been reported to date. Results: With the development of leaves, the content of polysaccharides increased first and the highest content was found at the F3 stage (the third larger full expanded leaf). A total of 499710194 clean reads were obtained using C. paliurus genomic data and were assembled into 296593 unigenes. Among 4708 identified DEGs, 429 DEGs were up-regulated and 451 DEGs were down-regulated from F1 stage (the smallest full expanded leaf) to F2 stage (the second larger full expanded leaf), 630 DEGs were up-regulated and 60 DEGs were down-regulated from F2 stage to F3 stage, and 1833 up-regulated and 1816 down-regulated DEGs from F3 stage to F4 stage. Forty DEGs associated with GT belong to 13 GT families. Among them, only one gene was down-regulated from F1 stage to F2 stage, two genes were down-regulated from F2 to F3 stages, and 23 genes were down-regulated and 15 genes were up-regulated from F3 stage to F4 stage, respectively. A significant correlation exists between the five unigenes and the polysaccharide content. UDP-glucose 4-epimerase gene was significantly positively correlated with the polysaccharide content. A pathway map for the biosynthesis of C. paliurus polysaccharide was proposed. Among 150 transcription factors identified from DEGs, the majority was members of the AP2/ERF family (21, 14%), followed by the C2H2 family (14, 9.33%), the MYB family (12, 8%), the C2C2-GATA family (10, 6.67%), the GRAS family (9, 6%), and the zf-HD family (7, 4.67%). Conclusions: These results identified genes involved in the biosynthesis of Cyclocarya paliurus polysaccharides during different leaf developmental stages and provided evidence for the change of polysaccharide content during the development of C. paliurus leaves. Possible synthetic pathways and related transcription factors were suggested. This study provides information for the screening of polysaccharide biosynthesis related genes and elucidates the mechanism underlying polysaccharide biosynthesis in C. paliurus.

Layered double hydroxide (LDH)-supported Pd nanocatalysts (Pd/LDH-OH) were prepared by ultrasonic-assisted reduction at 30 °C using an ultrasonic bath at a frequency of 25 kHz and an input power of 400 W for 30 min without the addition of any stabilizing reagent or chemical reductant, using LDH with a layered structure and interparticle mesoporosity as the reductant and carrier. This kind of pore structure allows ultrasound waves to spread inside the pore and make ultrasound directly act on the surface hydroxyl groups of LDH, producing highly reductive free radicals ( H). The reductive free radicals rapidly reduced Pd2+ to Pd0, forming ultrafine Pd nanoparticles (PdNPs) with a particle size distribution of 1.85 nm–3.45 nm and an average particle size of 2.52 nm. The surface hydroxyl groups were converted to exposed oxygen groups after dissociation of hydrogen radicals, which is beneficial for anchoring and dispersing the resultant PdNPs. The resultant PdNPs were uniformly dispersed on the surface of the LDH carrier. The yield of the Suzuki coupling reaction between 4-bromotoluene and phenylboronic acid catalyzed by Pd/LDH-OH at 60 °C was 95.49% for 5 min and the TOF was 190.98 min−1. After repeated for 5 times, the yield was maintained at 84.59%. The prepared Pd/LDH-OH nanocatalyst and the catalytic system are useful for Suzuki-Miyaura coupling reactions of N- and S-heterocyclic substrates. This provides an efficient and green approach for the preparation of supported nanopalladium catalysts.

The Cu2+doped porous CdIn2S4 microspheres (Cu@CdIn2S4) with better photocatalytic performance were prepared by sodium dodecyl sulphate (SDS)-assisted hydrothermal technology. The Cu@CdIn2S4 were characterized by SEM, XPS, XRD and DRS. The effects of Cu2+ doping amount on the morphology, structure and photocatalytic hydrogen production performance of CdIn2S4 were studied. The porous Cu@CdIn2S4 microspheres were flower shape of a average diameter of 3-5 μm and their maximum absorption edge was up to 700 nm. The Cu2+ doping was good for the improvement of photocatalytic performance. Cu@CdIn2S4 with 0.3wt% Cu2+doping amount possessed the highest hydrogen production rate of 1248.1 μmol/(h·g), much more than that of pure CdIn2S4.

The bio‐synthesis of palladium nanocubes (PdNCs) was realised using pine needle extract as the reducing agent and cetyl trimethyl ammonium bromide as the capping agent. As an eco‐friendly and readily available biomass, pine needle extract avoided the use of highly polluting chemical reducing agents. The growth process of PdNCs was analysed using ultraviolet–vis and Fourier transform infrared spectroscopy. Flavonoids, esters, terpenoids and polyhydric alcohols, which contain reductive groups, were mainly responsible for the transition of Pd(2+) ions to PdNCs. The morphology and structure of PdNCs were characterised using transmission electron microscopy (TEM), high‐resolution TEM, selected area electron diffraction and X‐ray diffraction. It was indicated that the as‐prepared PdNCs displayed a relatively high purity and good crystallinity with a face‐centred cubic structure and exhibited sizes ranging from 6.11 to 29.51 nm with an average particle size of 11.18 nm. In the methanol electro‐oxidation reaction, the PdNCs enclosed by {100} facets exhibited superior electro‐catalytic activity to commercial Pd/C, which was rarely reported in other bio‐synthesis processes for Pd catalysts. Meanwhile, the PdNCs showed excellent anti‐poisoning ability and long‐term stability. This study reveals the possibility of preparing shape‐controlled PdNCs with a specific structure and excellent electro‐catalytic activity.