23 research outputs found
Liquid-Phase Hydrogenation of Cinnamaldehyde: Enhancing Selectivity of Supported Gold Catalysts by Incorporation of Cerium into the Support
The gold nanocrystals supported over CeO<sub>2</sub>-containing
mixed-metal oxides were synthesized by a reductionâdeposition
approach followed by calcination. The zerovalent Au<sup>0</sup> was
obtained from the reduction of Au<sup>3+</sup> 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 Cî»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 CeO<sub>2</sub>, the morphology
effect of Au, and the interaction of Au and CeO<sub>2</sub> components
in the support, revealed by XRD, HRTEM, and XPS. The increasing Ce<sup>3+</sup> 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 Cî»C bond versus
Cî»O bond. A control experiment showed that the Au/CeO<sub>2</sub> catalyst has a relatively low activity and selectivity under the
identical reaction conditions. This finding indicated that a better
dispersion and decreased size of CeO<sub>2</sub> 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 TiO<sub>2</sub> Nanocrystalline Films
Hot carrier and multiple exciton extractions from lead
salt quantum
dots (QDs) to TiO<sub>2</sub> single crystals have been reported.
Implementing these ideas on practical solar cells likely requires
the use of nanocrystalline TiO<sub>2</sub> thin films to enhance the
light harvesting efficiency. Here, we report 6.4 ± 0.4 fs electron
transfer time from PbS QDs to TiO<sub>2</sub> nanocrystalline thin
films, suggesting the possibility of extracting hot carriers and multiple
excitons in solar cells based on these materials
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., Li<sub>2</sub>CO<sub>3</sub> 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 Mg<sup>2+</sup> cations
were reacted to form a solid via a nucleationâcrystallization
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<sup>+</sup> cations were left in the solution after Mg<sup>2+</sup> cations were reacted with alkali solution, accompanied by
foreign Al<sup>3+</sup> cations. That is to say that the Mg<sup>2+</sup> cations can be incorporated into the layers of MgAl-LDH while Li<sup>+</sup> cations cannot. The findings indicated that Mg<sup>2+</sup> cations were almost completely extracted into the solid phase to
form the LDH. The Li<sup>+</sup> 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/BiVO<sub>4</sub> 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 BiVO<sub>4</sub> particles, that is, QD@LDH@BiVO<sub>4</sub>, was designed. Two sets
of consecutive Type-II band alignments were constructed to improve
photogenerated electronâhole separation in the triadic structure.
The efficient charge separation resulted in a 2-fold enhancement of
the photocurrent of the QD@LDH@BiVO<sub>4</sub> 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 âŒ1.0 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 2,202â2,222 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 âHeiye.â Moreover, the coding regions of LcFLS genes of other MLM cultivars were almost identical to that of âHeiye.â 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
Genotypes for the 14 SNP set in the cultivars used for the stability study.
<p>SD: Shuidong; HY: Heiye; NMC: Nuomici; QZHL: Qinzhouhongli; LSXL: Lingshanxiangli; YH: Yuanhong; DCZ: Dachenzi; LZ: Lanzhu; XFZ: Xiafanzhi; NDWHL: Nandaowuheli.</p><p>Genotypes for the 14 SNP set in the cultivars used for the stability study.</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 PtâSn catalyst for DHP, in which metallic Pt centers
are dispersed homogeneously in small raft-like clusters on MgÂ(Sn)Â(Al)ÂO
and form strong interactions with the Sn<sup>IV/II</sup> sites confined
in MgÂ(Al)O lattices. A propene selectivity of >99% at 550 °C
with a conversion close to the equilibrium (specific rate of 0.96
s<sup>â1</sup> for propene formation) and a propene selectivity
of >98% (specific rate of 1.46 s<sup>â1</sup>) even under
600
°C have been produced by highly dispersed Pt sites in Pt/MgÂ(Sn)Â(Al)ÂO.
The PtâSn interactions and Sn<sup>IV/II</sup> confinement were
revealed to afford the catalyst with good durability. No visible sintering
of Pt clusters was observed in the long-term DHP reaction