Mindong Chen

Facile synthesis of novel Ag3PO4 tetrapods and the {110} facets-dominated photocatalytic activity

Highly uniform silver orthophosphate microcrystals with novel tetrapod morphology are, for the first time, synthesized via a simple hydrothermal route with the assistance of urea. The effect of active crystal facets on the photocatalytic activity is principally investigated. The silver orthophosphate tetrapods exhibit significantly higher visible light activity than the polyhedrons for the degradation of toxic organic compounds due to the highly exposed {110} facets.

Branching growth of novel silver phosphate dendrites and the greatly improved photocatalytic activity by the active {110} facets

Herein, novel Ag3PO4 dendrites, including highly-branched tetrapods (HBTs), three-dimensional towers (TDTs), and threefold-overlapped tetrapods (TOTs), are achieved by a facile precipitation method. Surprisingly, the apparent reaction rate constants of the HBTs, TDTs and TOTs are 144.3, 87.9 and 50.4 times higher than that of N-doped TiO2 (NT), respectively. The different activities of the Ag3PO4 dendrites have been mainly attributed to the exposed high-energy {110} facets. This work represents a big step toward exploring branching growth and improving photocatalytic properties.

Controllable growth of novel BiPO4 dendrites by an innovative approach and high energy facets-dependent photocatalytic activity

For monoclinic BiPO4, it seems fairly difficult to acquire the other novel nanostructures. Herein, we, for the first time, report the controllable syntheses of the six branch- and snowflake-like monoclinic BiPO4 dendrites by ethylenediamine tetraacetic acid. It is surprising that the branch intersection fringes of dendrite have a twinning crystal structure. Moreover, the six branch dendrites show a higher photocatalytic activity than the other two samples, which has been mainly ascribed to its high-energy (002) facet exposed, high light absorbance, and BET area. This innovative branching growth strategy represents a major breakthrough with fairly few nanostructures (only nanoparticles, nanorods and octahedrons available) in the existing literature.

An innovative anion regulation strategy for energy bands of semiconductors: a case from Bi2O3 to Bi2O(OH) 2SO4

How to develop a new, efficient photo catalyst is still a big challenge to us. A suitable band gap is the key for light absorption of semiconductor. Herein, an innovative anion intercalation strategy is, for the first time, developed to regulate the energy band of semiconductor. Typically, we introduce a layered sulfate compound (Bi2O(OH)2SO4) as a new photo catalyst, which has not been known before. Both partial density of states (PDOS) and total density of states (TDOS) have demonstrated that compared with Bi2O3 (2.85u2005eV), the band gap of Bi2O(OH)2SO4 has been widened to 4.18u2005eV by the intercalation of sulfate anion. Moreover, the band gap width of oxyacid salt compound is mainly predominated by the number of the outmost electrons (NOE) of central atom of anion. This study suggests that new photo catalysts can be developed by grouping anions with the existing oxides or sulfides.

An innovative glycine complexing approach to silver phosphate myriapods with improved photocatalytic activity

Without using any templates, surface-etched Ag3PO4 myriapods were synthesized by a simple glycine complexing method. The unique surface structure endows Ag3PO4 with a high specific surface area, thus leading to greatly improved photocatalytic degradation activity for Rhodamine B compared to that for the solid structures. The glycine complexing strategy is expected to be extended to the preparation of other photocatalysts.

Surface Control and Photocatalytic Activity of Branched Silver Orthophosphate Dendrites

Surface control is important to improve the adsorption, reactivity, and selectivity of materials. Limited by thermodynamic crystal habit, however, it is still a big challenge to control active surfaces simply and effectively. In this report, we introduce an innovative branching‐growth methodology to control the surfaces of Ag3PO4 without the use of screening agents or templates. Typically, an inu2005situ seed‐induced branching growth strategy is developed to achieve the surface control of silver orthophosphate, in which the crystal growth changes from mass‐transport‐limited branching growth to pH‐dependent faceting growth. As a result, numerous unprecedented, highly branched Ag3PO4 dendrites have been acquired. The apparent reaction rate constants of these dendrites are 2.55–3.76u2005times higher than conventional cubes for the degradation of rhodamineu2005B dye. This study provides a new, effective avenue to control the surfaces of materials, which has made a big breakthrough to the improvement of the performances of materials. This is important for us to obtain materials or devices with greatly improved performances.

NOVEL HIERARCHICAL NANORODS OF SILICON-DOPED Bi2O2CO3 AND ITS PHOTOCATALYTIC ACTIVITY

The silicon-doped Bi2O2CO3 nanorods with the interesting hierarchical structure are synthesized by a simple hydrothermal method. The samples are characterized by XRD, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), Ultraviolet-visible diffuse reflectance spectra (UV-DRS) and nitrogen sorption isotherms. It is found that with the increase of silicon content, the XRD peak of the sample significantly shifts toward a low diffraction angle and the particle morphologies change from nanosheets, nanoflowers to hierarchical nanorods. Moreover, the silicon-doped Bi2O2CO3 hierarchical nanorods exhibit improved photocatalytic degradation activities for different types of dyes under simulated solar light irradiation. The improved activity has been mainly attributed to the unique hierarchical nanorods structure and the formation of Si–O–Bi bonds.

Etched titania nanoplates by both HF and HAc and the photocatalytic activities for degradation of pollutants

A HF/HAc-containing system has been developed to synthesize uniform anatase TiO2 nanoplates with controllable thickness. The interesting etch figures caused by misorientations on the {001} facets of anatase TiO2 nanoplates are found, leading to the obvious transformation from square edges to round ones. Remarkably, the typical nanoplates exhibit a 6 times higher activity than commercial Degussa P25 for the RhB degradation, due to the thin thickness and highly exposed {001} facets.

ONE-POT SYNTHESIS OF INTERESTING 3D γ-MnOOH NETWORKS

Three-dimensional (3D) γ-MnOOH networks are successfully prepared by one-pot solvothermal method without using any catalyst. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). It is found that the amounts of urea and H2O2 added, reaction temperature and time have important influences on the samples. It is interesting that the 3D networks are formed from the oriented attachment (OA) of Mn3O4 octahedrons; and that the phase transformation from Mn3O4 to γ-MnOOH occurs via the protonation of Mn3O4. This study is expected to offer a facile approach to the syntheses of new, intricate nanostructures.