Dingze Lu

Study of the enhanced visible-light-sensitive photocatalytic activity of Cr2O3-loaded titanate nanosheets for Cr(VI) degradation and H2 generation

Visible-light-sensitive titanate nanosheets (TNSs) were synthesized with Cr2O3 successfully loaded and well dispersed on Cr(III)-TNSs by a one-step hydrothermal method for enhanced photocatalytic activity. As in our previous reports, the as-prepared samples clearly exhibited a porous flake-like structure with a large specific surface area (300–400 m2 g−1). Accompanied with the hydrothermal growth of the TNSs, the loaded Cr2O3 not only influenced the layered structure of the TNSs, but also brought about a remarkable enhancement of the visible-light response and the separation of photogenerated carriers. The XPS fitting results indicated that the Cr ions mainly existed in the trivalent form and caused a change in the binding states towards Ti and O. Based on the evaluation of the photocatalytic activity, it was found that the Cr(III)-TNSs obtained a significant improvement for RhB and K2Cr2O7 (Cr(VI)) degradation under visible-light irradiation, which was attributed to retarding the charge recombination and the effective electron transfer from Cr2O3 to TNSs. The better photocatalytic activity was obtained with an optimal content (0.5 at%) of Cr3+, and the degradation rate (Kapp) was 2.9-fold and 4.1-fold, respectively, as compared to TNSs. The samples were also evaluated in photocatalytic H2 generation with the photodeposition of Pt nanoparticles as cocatalysts. The results showed that the visible-light H2 production rate of Pt0.25/Cr(III)-TNSs (0.25 wt% of Pt) was observably enhanced under the efficient sacrificial agent/water system, giving a relatively high H2 generation rate of 473 μmol h−1 g−1 at 0.5 at% of Cr3+ content. The cyclic tests demonstrated the good stability and recycling performance of the samples. Alternative mechanisms for the visible-light-sensitive photocatalytic activity were also proposed.

A surfactant-free solvothermal synthesis of Cu2O microcrystals and their photocatalytic activity

The Cu2O octahedral microcrystals have been successfully fabricated by a surfactant-free solvothermal approach. The morphology and structure of the as-prepared sample were characterized by scanning electron microscopy, X-ray powder diffraction and UV-Vis spectroscopy. It was found that the structure and morphology of Cu2O microcrystals were strongly affected by synthesis time and temperature. Based on the time-dependent experiment, the possible formation mechanism of Cu2O octahedral microcrystals was proposed. The photocatalytic activities of as-prepared Cu2O samples were also evaluated for degradation of methyl orange under visible-light irradiation. The results showed that the Cu2O synthesized at 180 °C for 4 h had a better photocatalytic performance due to its high percentage of exposed (111) crystal facet and the lowest band gap energy.

Controllable preparation and catalytic performance of Pt/metal oxide nanocomposites for glycerol hydrogenation

Abstract A surfactant-free and facile one-pot synthetic route in the alkaline glycol system has been developed for the fabrication of Pt/metal oxide nanocomposites. The structure and chemical composition of the as-prepared products were characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM) and inductively coupled plasma-mass spectrometry (ICP-MS). It is found that the corresponding precursors have been completely converted into the Pt/metal oxide nanocomposites. As for Pt/ZnO nanocomposites, the Pt loading amount can be controlled by the different molar ratios of Pt and Zinc precursor, while Pt nanoparticle sizes can be adjusted through the different mass of NaHCO3 added. In addition, the catalytic activities of Pt/metal oxide nanocomposites for glycerol hydrogenation were also studied. When the amount of platinum metal was kept constant, different metal oxide supporters demonstrated different levels of catalytic activation. The diverse reason of the catalytic activation for the different Pt/metal oxide nanocomposites was also speculated.