Showing papers by "Wenting Wu published in 2015"

Cu-N dopants boost electron transfer and photooxidation reactions of carbon dots.

Abstract: The broadband light-absorption ability of carbon dots (CDs) has inspired their application in photocatalysis, however this has been impeded by poor electron transfer inside the CDs. Herein, we report the preparation of Cu–N-doped CDs (Cu-CDs) and investigate both the doping-promoted electron transfer and the performance of the CDs in photooxidation reactions. The Cu–N doping was achieved through a one-step pyrolytic synthesis of CDs with Na2[Cu(EDTA)] as precursor. As confirmed by ESR, FTIR, and X-ray photoelectron spectroscopies, the Cu species chelates with the carbon matrix through Cu–N complexes. As a result of the Cu–N doping, the electron-accepting and -donating abilities were enhanced 2.5 and 1.5 times, and the electric conductivity was also increased to 171.8 μs cm−1. As a result of these enhanced properties, the photocatalytic efficiency of CDs in the photooxidation reaction of 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate is improved 3.5-fold after CD doping.

Cu-N dopants boosting electron transfer and photooxidation reaction of carbon dots

Abstract: The broadband light-absorption ability of carbon dots (CDs) has inspired their application in photocatalysis, however this has been impeded by poor electron transfer inside the CDs. Herein, we report the preparation of Cu-N-doped CDs (Cu-CDs) and investigate both the doping-promoted electron transfer and the performance of the CDs in photooxidation reactions. The Cu-N doping was achieved through a one-step pyrolytic synthesis of CDs with Na2 [Cu(EDTA)] as precursor. As confirmed by ESR, FTIR, and X-ray photoelectron spectroscopies, the Cu species chelates with the carbon matrix through Cu-N complexes. As a result of the Cu-N doping, the electron-accepting and -donating abilities were enhanced 2.5 and 1.5 times, and the electric conductivity was also increased to 171.8 μs cm(-1) . As a result of these enhanced properties, the photocatalytic efficiency of CDs in the photooxidation reaction of 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate is improved 3.5-fold after CD doping.

Synthesis of nanocomposites with carbon–SnO2 dual-shells on TiO2 nanotubes and their application in lithium ion batteries

Abstract: Through the introduction of well-distributed tin oxide nanocrystals on the surface of pre-prepared TiO2 nanotubes and carbon coating, novel TiO2/SnO2–C double-shell nanotubes have been synthesized. As an anode material of Li-ion batteries (LIBs), DSNTs exhibit excellent long-term cycling stability (256.0 mA h g−1 at 1 A g−1 after 710 cycles) and satisfactory rate capability, which are ascribed to the synergetic effects of a unique combination of material properties in the well-designed conductive matrix: high volume stable titanium dioxide to form a one-dimensional (1D) core section to maintain the structure, large theoretical capacity tin oxide as a functional layer to increase capacity and highly conductive carbon as a buffer layer to accelerate charging rate.

Synergetic effect of C*N^N/C^N^N coordination and the arylacetylide ligands on the photophysical properties of cyclometalated platinum complexes

Abstract: Six coordinated Pt(II) complexes were prepared, in which the C*N^N or the C^N^N ligand were used to form the Pt(II) coordination center. For each coordination profile, three different arylacetylide ligands were used, i.e. naphthalenediimide (NDI), pyrenyl (Py) and naphthaleneimide (NI) acetylides. The electrochemical and the photophysical properties of the complexes were studied with steady-state and time-resolved absorption and emission spectroscopy, cyclic voltammetry and DFT calculations. The photostability and the photoluminescent properties of the complexes are finely tuned by the photoredox and photophysical properties of the arylacetylide ligands and the C*N^N/C^N^N Pt(II) coordination center. The triplet excited states of the complexes are an intraligand feature and the lifetime is long (90.1 μs). The photophysical properties of the complexes were rationalized with DFT calculations. The complexes were used as triplet photosensitizer for triplet–triplet annihilation upconversion. The upconversion quantum yield was up to 29.7%. The results are useful for future designing of Pt(II) complexes showing strong visible light-absorption, RT phosphorescence and long-lived triplet excited states.

Photocatalytic H2 evolution from NADH with carbon quantum dots/Pt and 2-phenyl-4-(1-naphthyl)quinolinium ion

Abstract: Carbon quantum dots (CQDs) were simply blended with platinum salts (K2PtCl4 and K2PtCl6) and converted into a hydrogen-evolution co-catalyst in situ, wherein Pt salts were dispersed on the surface of CQDs under photoirradiation of an aqueous solution of NADH (an electron and proton source) and 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh+−NA) employed as an organic photocatalyst. The co-catalyst (CQDs/Pt) exhibits similar catalytic reactivity in H2 evolution as that of pure Pt nanoparticles (PtNPs) although the Pt amount of CQDs/Pt was only 1/200 that of PtNPs previously reported. CQDs were able to capture the Pt salt acting as Pt supports. Meanwhile, CQDs act as electron reservoir, playing an important role to enhance electron transfer from QuPh+−NA to the Pt salt, which was confirmed by kinetic studies, XPS and HRTEM.

Intramolecular Charge Transfer‐Enhanced BODIPY Photosensitizer in Photoinduced Electron Transfer and Its Application to Photoxidation under Mild Condition

Abstract: Photoinduced electron transfer process is a crucial step in photooxidation to obtain synthetic chemicals. However, the driving forces of electron transfer as priority in all have been rarely studied in stepwise detail. Herein, we report a series of BODIPY derivatives with an emphasis on the intramolecular charge transfer, enhancing the key step of photoinduced electron transfer process and photooxidation performances. A series of novel BODIPY photosensitizers (B-1–B-5) were prepared, wherein diethylamine amino of B-3 as charge injection group was conjugated to the 2,6-diiodo-styryl-BODIPY, and the electron transfer impetus was enhanced 1.6 times due to its more negative redox potentials. These results were also confirmed by the DFT/TDDFT calculation. Without pure oxygen, B-3 still can exhibit an exceptional performance in photoxidative aromatization of 1,4-DHP under mild condition. After irradiation for 28 min, the conversion rate came to 98.2%.

Construction of Erythrinane Skeleton via Pd(0)‐Catalyzed Intramolecular Dearomatization of para‐Aminophenols.

Abstract: A novel Pd(0)-catalyzed intramolecular arylative dearomatization of substrates having a p-aminophenol subunit and an alkyl tether bearing an ortho-haloaryl substituent is shown to yield products representing the erythrinane skeleton and related spirocyclic compounds.