Qing-Chi Xu

3D nano-macroporous structured TiO2-foam glass as an efficient photocatalyst for organic pollutant treatment

This work reports the preparation of 3D nano-macroporous structured TiO2-foam glass (p-TiO2/FG) as an efficient photocatalyst for the degradation of organic pollutants in water. Nanoporous TiO2 film was coated on macroporous foam glass by using a simple sol–gel coating method. In this work, we used waste glass to prepare foam glass with suitable apparent density (0.98 g cm−3) and high open porosity, which facilitated direct light absorption by the TiO2 film. Especially, the foam glass had a high adsorption capability for methylene blue (MB), which increased the quantity of organic pollutant to come in contact with TiO2 through means of adsorption and hence improved the photo-degradation efficiency. The p-TiO2/FG exhibited much higher photocatalytic activity than that of the TiO2/FG without a 3D nano-macroporous structure, which was attributed to the increase of reaction sites on p-TiO2/FG generated from its special 3D nano-macroporous structure. Additionally, the p-TiO2/FG presented high stability and recyclability, retaining high photocatalytic activity even after 10 cycles, which was mainly attributed to the uniform and stable coating of TiO2 film on the foam glass.

Ligand-triggered electrostatic self-assembly of CdS nanosheet/Au nanocrystal nanocomposites for versatile photocatalytic redox applications

A facile and efficient ligand-triggered electrostatic self-assembly strategy has been developed to fabricate a series of Au/CdS nanosheet (Ns) (Au-CdS Ns) nanocomposites with varied weight addition ratios of Au nanoparticles (NPs) by judiciously utilizing the intrinsic surface charge properties of assembly units, through which uniform dispersion and controllable deposition of Au NPs on the CdS Ns were achieved. Versatile probe reactions including photocatalytic oxidation of an organic dye pollutant, selective photocatalytic reduction of aromatic nitro compounds and photocatalytic hydrogen production reactions under visible light irradiation and ambient conditions were used to systematically evaluate the photoredox performances of the as-assembled well-defined Au-CdS Ns nanocomposites. It was unveiled that the photoactivities of Au-CdS Ns nanocomposites strongly depend on the weight addition ratio of Au NPs and the addition of an excess amount of Au NPs is detrimental to the separation of photogenerated charge carriers from CdS Ns. With the optimum addition amount of Au NPs (1 wt%), it was found that spontaneous assembly of Au NPs on the CdS Ns remarkably prolonged the lifetime of the photogenerated charge carriers from CdS Ns under visible light irradiation, thus resulting in significantly enhanced photocatalytic redox activities of Au-CdS Ns nanocomposites compared with those of CdS Ns. The crucial role of Au NPs in the photoredox reactions as efficient electron traps rather than plasmonic sensitizers was determined. Moreover, predominant active species responsible for the photocatalytic process were unambiguously determined and a possible photocatalytic mechanism was elucidated. It is anticipated that our work could open up a new avenue to rationally prepare various 2D semiconductors-metal nanocomposites by utilizing such a simple and efficient self-assembly strategy for extensive photocatalytic applications in a myriad of fields.