Jianqi Ma

Synthesis and characterization of Cu2O/Au and its application in catalytic reduction of 4-nitrophenol

Monodispersed Cu2O spherical colloids with diameter of about 300 nm were prepared by a facile additive-assisted complex-precursor solution method. Core-shell structure Cu2O/Au composites, constructed by spherical Cu2O core and Au nanoparticles shell, were obtained via galvanic replacement method. The morphology, microstructure and optical properties of the Cu2O/Au composites were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectra and ultraviolet-visible absorption. The results showed that Au NPs with an average size of 12 nm were uniformly distributed on the surface of the Cu2O spheres with size about 300 nm. Cu2O/Au composites exhibit high catalytic activity toward 4-NP reduction at room temperature.

Modified photodeposition of uniform Ag nanoparticles on TiO2 with superior catalytic and antibacterial activities

Abstract Photocatalytic reduction is a facile and effective route to deposit Ag nanoparticles (NPs) on TiO2. Nevertheless, it is difficult to produce Ag NPs that have small particle size and uniform distribution on TiO2 to form core–shell structure TiO2@Ag composites by straightforward photodeposition. In this study, monodisperse TiO2 spheres composed of anatase nanocrystals were directly employed as templates to deposit small and homogeneously dispersed Ag NPs by modified photodeposition procedure. To prove the feasibility of the innovative method, we evaluated the catalytic performance and bactericidal efficacy of the as-prepared samples based on the characterizations, since there is strong dependence between size and dispersion of Ag NPs and catalytic performance and inhibition of bacterial growth, where smaller and more highly dispersed Ag NPs displayed better antimicrobial and catalytic properties. The results indicate that the modified photodeposition route can effectively prevent TiO2 spheres themselves from aggregating and Ag NPs from rapid overgrowing on the TiO2 surface in the deposition process. The superior bactericidal and catalytic properties of the TiO2@Ag composites are largely attributed to the small and highly dispersed Ag NPs on TiO2 spheres.Graphical Abstract

Properties of magnetic carbon nanomaterials and application in removal organic dyes

Magnetic carbon nanomaterials were prepared facilely by one step hydrothermal synthesis method using biologically regenerated glucose as carbon sources and ferric ammonium citrate as iron sources. As-synthesized nanomaterials were characterized by means of SEM, TEM, XRD, N2 adsorption-desorption, VSM and XPS etc. techniques. Results show as-prepared magnetic nanomaterials are sphere particles with aggregation state and magnetic α-Fe particles are enclosed by carbon matrixes. With increase of calcination temperature, the degrees of the sample aggregation decrease, whereas the average particle sizes, BET specific surface areas and saturation magnetizations increase. The carbon with graphite structure has higher adsorption efficiency than that of amorphous carbon for organic dye rhodamine B in water. Whereas the iron with amorphous structure shows higher photocatalytic activity than that of the iron with crystalline structure for the degradation of rhodamine B. And rhodamine B in water can almost be degraded completely through the combination of adsorption and photocatalysis.

Fabrication of core–shell TiO2@CuS nanocomposite via a bifunctional linker-assisted synthesis and its photocatalytic performance

Monodisperse anatase TiO2 microspheres were prepared by a modified sol–gel method and then coupled with CuS nanoparticles (NPs) to prepare non-core–shell TiO2/CuS composite (denoted as TiO2/CuS) and core–shell TiO2@CuS composite (denoted as TiO2@CuS), respectively, by two different fabricating methods, namely direct deposition and bifunctional linker-assisted assembly. The morphological, structural, and optical properties of both the TiO2/CuS and TiO2@CuS composites were characterized using TEM, HR-TEM, EDS mapping images, XRD, XPS, and UV–Vis DRS. Their visible-light-driven photocatalytic performance for degradation of methylene blue was comparatively studied. Results indicate: (1) as bifunctional linker between CuS and TiO2, 2,3-dimercapto-succinic acid (DMSA) enables CuS NPs to be anchored tightly onto the DMSA-functionalize TiO2 surface with small particle size, narrow size distribution, conformal coverage, intimate contact, and strong interaction with TiO2 to form TiO2@CuS. (2) Without using DMSA, the directly deposited CuS NPs tend to aggregate and are loaded randomly and loosely on the bare TiO2 without forming well-defined heterojunction due to the lattice mismatch between CuS and TiO2, even some CuS NPs are detached from the surface of TiO2 and thus TiO2/CuS was obtained. (3) TiO2@CuS exhibits superior synergistic effect and corresponding photocatalytic activity to TiO2/CuS, and the significant difference between their photocatalytic properties is mainly attributed to their distinct microstructure caused by the different assembling methods.

CoFe2O4@TiO2@Au Core-Shell Structured Microspheres: Synthesis and Photocatalyltic Properties

A facile and efficient method for fabrication of magnetic composite microspheres CoFe2O4@TiO2@Au is demonstrated. The shells of anatase TiO2 were coated onto a magnetic CoFe2O4 core via liquid-phase deposition procedure, and then Au nanoparticles were deposited onto CoFe2O4@TiO2 microspheres through seed-mediated growth. XRD, TEM, and VSM were used to investigate the structure, morphology and magnetic properties of the samples, their photocatalytic activity were also tested. Heterostructure of CoFe2O4@TiO2@Au was confirmed by different measurements. Compared to unmodified CoFe2O4@TiO2 microspheres, CoFe2O4@TiO2@Au microspheres showed higher photocatalytic activity for Rhodamine B (RhB) degradation in water.