Liquid-Phase Hydrogenation of Cinnamaldehyde: Enhancing Selectivity of Supported Gold Catalysts by Incorporation of Cerium into the Support

The gold nanocrystals supported over CeO₂-containing mixed-metal oxides were synthesized by a reduction–deposition approach followed by calcination. The zerovalent Au⁰ was obtained from the reduction of Au³⁺ ion by the hydrolysis of sucrose in an aqueous solution. The thermal post-treatment led to supported gold catalysts, in which Au nanoparticles with adjustable sizes were anchored onto the mixed oxides. The incorporation of cerium (Ce) into the support remarkably enhanced the selectivity toward CC bond (hydrocinnamaldehyde, HCAL, ca. 83%) in cinnamaldehyde hydrogenation than the catalyst with no cerium (ca. 42%) under a high conversion (above 91%). The enhancement of selectivity to HCAL could be attributed to the decreasing sizes of Au and/or CeO₂, the morphology effect of Au, and the interaction of Au and CeO₂ components in the support, revealed by XRD, HRTEM, and XPS. The increasing Ce³⁺ amount in the catalysts leads to more oxygen vacancies. The surface electron density of Au diminishes due to the presence of oxygen vacancies. The morphological and electronic aspects of Au particles result in favorable adsorption of CC bond versus CO bond. A control experiment showed that the Au/CeO₂ catalyst has a relatively low activity and selectivity under the identical reaction conditions. This finding indicated that a better dispersion and decreased size of CeO₂ in the mixed oxides could be the key factors to enhancing the selectivity of supported Au catalysts

Strong Electronic Coupling and Ultrafast Electron Transfer between PbS Quantum Dots and TiO₂ Nanocrystalline Films

Hot carrier and multiple exciton extractions from lead salt quantum dots (QDs) to TiO₂ single crystals have been reported. Implementing these ideas on practical solar cells likely requires the use of nanocrystalline TiO₂ thin films to enhance the light harvesting efficiency. Here, we report 6.4 ± 0.4 fs electron transfer time from PbS QDs to TiO₂ nanocrystalline thin films, suggesting the possibility of extracting hot carriers and multiple excitons in solar cells based on these materials

Boosting the Carrier Lifetime and Optical Activity of CsPbX₃ Nanocrystals through Aromatic Ligand Passivation

Ligand engineering is crucial for tuning the structural and optoelectronic properties of perovskite nanocrystals (NCs), which also improves their stability. In contrast to the typically used long-chain alkylamine ligands, we successfully introduced an aromatic 1-(p-tolyl)ethylamine (PTEA) ligand to synthesize the CsPbX3 (X = Br or I) NCs. The CsPbI3 and CsPbBr3 NCs demonstrated long carrier lifetimes of ∼877 and 49 ns, respectively, as well as high photoluminescence quantum yields (PLQYs) of ∼99% and 95%, respectively. Furthermore, such NCs realized excellent long-term stability in an ambient atmosphere without obvious degradation over one month. All of these properties were better than the properties of NCs coated with the conventional alkylamine ligands. The high performance of these NCs was discussed with the effective surface passivation by PTEA. Our finding suggests a facile and effective ligand (PTEA) for modulating perovskites, achieving enhancement of both the carrier lifetime and the PLQY

Highly Efficient Separation of Magnesium and Lithium and High-Valued Utilization of Magnesium from Salt Lake Brine by a Reaction-Coupled Separation Technology

Lithium extraction from salt lake brines is one of the most important pathways for obtaining Li-related products, e.g., Li₂CO₃ and LiOH, and for further fabricating electric energy-storage products, e.g., lithium ion batteries. The high Mg/Li ratio and high Mg content are remarkable characteristics of the salt lakes in the Qaidam Basin in China, making the Mg/Li separation and Li extraction rather difficult. Herein, we proposed a reaction-coupled separation technology for Mg/Li separation from brine with a high Mg/Li ratio. The core idea of this technology is that the Mg²⁺ cations were reacted to form a solid via a nucleation–crystallization separation method. The solid product was MgAl-layered double hydroxide (MgAl-LDH), a widely used and high-valued product in the family of LDHs. The Li⁺ cations were left in the solution after Mg²⁺ cations were reacted with alkali solution, accompanied by foreign Al³⁺ cations. That is to say that the Mg²⁺ cations can be incorporated into the layers of MgAl-LDH while Li⁺ cations cannot. The findings indicated that Mg²⁺ cations were almost completely extracted into the solid phase to form the LDH. The Li⁺ cations remained in the solution having a weight loss less than 8%, which is an excellent level of Li extraction from the brine with a high Mg/Li ratio. The effects of reaction parameters, e.g., ionic strength, nucleation rotating speed, Mg/Al ratio, and crystallization temperature and time, on the separation performance and lithium loss were investigated. The optimal conditions were derived for lower lithium loss and more outstanding Mg/Li separation performance, which can be a useful guide for environmentally friendly and sustainable Li extraction from the brine

Highly Enhanced Photoelectrochemical Water Oxidation Efficiency Based on Triadic Quantum Dot/Layered Double Hydroxide/BiVO₄ Photoanodes

The water oxidation half-reaction is considered to be a bottleneck for achieving highly efficient solar-driven water splitting due to its multiproton-coupled four-electron process and sluggish kinetics. Herein, a triadic photoanode consisting of dual-sized CdTe quantum dots (QDs), Co-based layered double hydroxide (LDH) nanosheets, and BiVO₄ particles, that is, QD@LDH@BiVO₄, was designed. Two sets of consecutive Type-II band alignments were constructed to improve photogenerated electron–hole separation in the triadic structure. The efficient charge separation resulted in a 2-fold enhancement of the photocurrent of the QD@LDH@BiVO₄ photoanode. A significantly enhanced oxidation efficiency reaching above 90% in the low bias region (i.e., <i>E</i> < 0.8 V vs RHE) could be critical in determining the overall performance of a complete photoelectrochemical cell. The faradaic efficiency for water oxidation was almost 90%. The conduction band energy of QDs is ∼1.0 V more negative than that of LDH, favorable for the electron injection to LDH and enabling a more efficient hole separation. The enhanced photon-to-current conversion efficiency and improved water oxidation efficiency of the triadic structure may result from the non-negligible contribution of hot electrons or holes generated in QDs. Such a band-matching and multidimensional triadic architecture could be a promising strategy for achieving high-efficiency photoanodes by sufficiently utilizing and maximizing the functionalities of QDs

SNP data for litchi

This file contains genotype data at 90 SNP loci for 96 litchi accessions sampled in China

A phylogenetic tree and population structure of 96 litchi accessions based on 90 informative SNPs.

<p>A phylogenetic tree and population structure of 96 litchi accessions based on 90 informative SNPs.</p

The relationship between observed genotypes and numbers of SNPs used.

<p>The relationship between observed genotypes and numbers of SNPs used.</p

Presentation_1_Cloning and Characterization of a Flavonol Synthase Gene From Litchi chinensis and Its Variation Among Litchi Cultivars With Different Fruit Maturation Periods.PDF

<p>Litchi (Litchi chinensis) is an important subtropical fruit tree with high commercial value. However, the short and centralized fruit maturation period of litchi cultivars represents a bottleneck for litchi production. Therefore, the development of novel cultivars with extremely early fruit maturation period is critical. Previously, we showed that the genotypes of extremely early-maturing (EEM), early-maturing (EM), and middle-to-late-maturing (MLM) cultivars at a specific locus SNP51 (substitution type C/T) were consistent with their respective genetic background at the whole-genome level; a homozygous C/C genotype at SNP51 systematically differentiated EEM cultivars from others. The litchi gene on which SNP51 was located was annotated as flavonol synthase (FLS), which catalyzes the formation of flavonols. Here, we further elucidate the variation of the FLS gene from L. chinensis (LcFLS) among EEM, EM, and MLM cultivars. EEM cultivars with a homozygous C/C genotype at SNP51 all contained the same 2,199-bp sequence of the LcFLS gene. For MLM cultivars with a homozygous T/T genotype at SNP51, the sequence lengths of the LcFLS gene were 2,202–2,222 bp. EM cultivars with heterozygous C/T genotypes at SNP51 contained two different alleles of the LcFLS gene: a 2,199-bp sequence identical to that in EEM cultivars and a 2,205-bp sequence identical to that in MLM cultivar ‘Heiye.’ Moreover, the coding regions of LcFLS genes of other MLM cultivars were almost identical to that of ‘Heiye.’ Therefore, the LcFLS gene coding region may be used as a source of diagnostic SNP markers to discriminate or identify genotypes with the EEM trait. The expression pattern of the LcFLS gene and accumulation pattern of flavonol from EEM, EM, and MLM cultivars were analyzed and compared using quantitative real-time PCR (qRT-PCR) and high-performance liquid chromatography (HPLC) for mature leaves, flower buds, and fruits, 15, 30, 45, and 60 days after anthesis. Flavonol content and LcFLS gene expression levels were positively correlated in all three cultivars: both decreased from the EEM to MLM cultivars, with moderate levels in the EM cultivars. LcFLS gene function could be further analyzed to elucidate its correlation with phenotype variation among litchi cultivars with different fruit maturation periods.</p

Lattice-Confined Sn (IV/II) Stabilizing Raft-Like Pt Clusters: High Selectivity and Durability in Propane Dehydrogenation

Catalytic dehydrogenation of propane (DHP) to propene is highly endothermic, requiring a high reaction temperature. Under harsh conditions, it has been a great challenge to maintain excellent propene selectivity and suppress the irreversible deactivation caused by sintering of metallic active centers. This work reports a highly selective and durable Pt–Sn catalyst for DHP, in which metallic Pt centers are dispersed homogeneously in small raft-like clusters on Mg­(Sn)­(Al)­O and form strong interactions with the Sn^IV/II sites confined in Mg­(Al)O lattices. A propene selectivity of >99% at 550 °C with a conversion close to the equilibrium (specific rate of 0.96 s^–1 for propene formation) and a propene selectivity of >98% (specific rate of 1.46 s^–1) even under 600 °C have been produced by highly dispersed Pt sites in Pt/Mg­(Sn)­(Al)­O. The Pt–Sn interactions and Sn^IV/II confinement were revealed to afford the catalyst with good durability. No visible sintering of Pt clusters was observed in the long-term DHP reaction