Huinian Zhang

Luminescence properties of transparent hybrid thin film covalently linked with lanthanide complexes

Novel hybrid thin films covalently doped with Eu3+ (Tb3+) have been prepared via direct routes involving co-condensation of tetraethoxysilane and phen-Si in the presence of Eu3+ (Tb3+) by spin-casting and their luminescence properties have been investigated in detail. Lanthanide ions can be sensitized by anchored phenanthroline in hybrid thin films. Excitation at the ligand absorption wavelength (272 nm) resulted in the strong emission of the lanthanide ions i.e. Eu3+ D-5(0)-F-7(J) (J=0, 1, 2, 3, 4) emission lines and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) due to the energy transfer from the ligands to the lanthanide ions.

Effective energy transfer and luminescence of LB films based on europium-substituted heteropolytungstate

The europium-substituted heteropolytungstate K13Eu(SiW11O39)(2) was successfully assembled into two lipids by LB technique for the first time. X-ray diffraction has shown a well defined lamellar for the LB films. The LB films have been characterized by fluorescence spectra and the characteristic luminescence behaviors were discussed. The ligand-metal charge transfer band could be observed in the spectra of the LB films, which could not be found in that of heteropolytungstate solid. The results of fluorescence spectra indicate the energy could be effectively transferred from ligands to the Eu3+ ions in the LB films and the luminescence efficiency was increased greatly. The influences of various lipids on the luminescence of polyoxometalates were investigated. The various interactions between monolayer and polyanions have different effect on the luminescence properties of europium-substituted heteropolytungstate.

The improvement of pitch activation by graphene for long-cycle Li–S batteries

It is interesting to convert industrial pitch to carbon based materials with high yield for energy storage owing to environmental and energy concerns. In this study, we activated coal tar pitch by a green process to obtain porous carbon sheets sandwiched by graphene, and further impregnated with 71% sulphur as the cathode for long-term cycling lithium–sulphur battery. In the presence of 4.0% of electrochemically exfoliated graphene flakes, the yield of carbon from pitch is as high as 72%, while the activation temperature of the pitch is as low as 700 °C. This carbon sheet has a high specific surface area of 2930 m2 g−1 and large pore volume of 1.5 cm3 g−1, which is nearly 3 times that of activated carbon derived from pitch without graphene. The cathode loaded with 71% sulfur (3.0 mg cm−2 of sulphur) demonstrated a discharge capacity of 1340 mA h g−1 at 0.05 C, which faded by only 0.001% per cycle at 1 C during 201–1500 cycles. Surface oxygen groups, 1.1 nm nanopore confinement and the sandwich structure of conductive graphene may contribute to the stable and reversible electrochemical reaction of the Li and sulphur clusters. Our investigation demonstrates that graphene can enhance the pitch activation to high quality microporous carbon and further confine sulphur species for long-term cycling Li–S batteries.

The synthesis of atomic Fe embedded in bamboo-CNTs grown on graphene as a superior CO2 electrocatalyst

A catalyst consisting of atomic iron embedded in a new hierarchical carbon matrix was synthesised, and this catalyst exhibited superior performance in CO2 electroreduction. Bamboo-like carbon nanotubes were catalytically grown by Fe3C nanocrystals on graphene co-doped with atomic iron and nitrogen by a new approach of electrochemical oxidation of graphene films in an FeCl4−-based ionic liquid followed by annealing. The highly selective generation of CO from CO2 was achieved at a low overpotential of 0.55 V with a maximum CO faradaic efficiency of ∼95% for over 12 h.

Dual-Ion-Mode MALDI MS Detection of Small Molecules with the O–P,N-Doped Carbon/Graphene Matrix

It is challenging to realize a dual-ion mode of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for detecting small molecules. Herein, graphene coated by porous amorphous carbon with P-O surface group and codoped by phosphorus and nitrogen (O-P,N-C/G) was synthesized from an aerogel formed by phytic acid, polyaniline, and electrochemically exfoliated graphene. The carbon material synthesized has the feature of large surface area (583 m2/g), good electrical conductivity, strong UV absorption, heteroatom doping, and surface functional groups suitable for laser- induced desorption/ionization. It was employed as a novel matrix suitable for both positive-ion and negative-ion modes in MALDI-TOF MS for the analysis of various small molecules including amino acids, small peptides, saccharides, drugs, and environmental pollutants, significantly outperforming control materials and a traditional CHCA (α-cyano-4-hydroxycinnamic acid) or 2,5-dihydroxybenzoic (DHB) matrix. Remarkably, the detection limit of the anticancer drugs (5-fluorouracil and ellagic acid) reaches 50 pmol. In addition, nice MALDI-TOF MS images can be mapped to detect mixed amino acids corresponding to homogeneous distribution of ion intensity. The monosaccharides and disaccharides can be distinguished by using the new matrix. Last but not least, it can be used to quantitatively detect glucose in human serum and soft drinks (glucose/fructose, 203.1 mM) without adding standards.