Deli Jiang

Modifiers-assisted formation of nickel nanoparticles and their catalytic application to p-nitrophenol reduction

Nickel nanoparticles with different sizes and morphologies were prepared with nickel chloride as the source of nickel and hydrazine hydrate as a reductant. Cetyltrimethyl ammonium bromide (CTAB), polyethylene glycol-10000 (PEG-10000), gelatin and their composites were used as modifiers in this research. The particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR). The effect of using single modifiers and their composites was investigated. The results revealed that the kind of modifier used had a significant effect on the morphology and size of the Ni nanostructure. The possible formation mechanism of nickel nanoparticles was also investigated. All of the formed nickel nanoparticles showed excellent catalytic activity in the reduction of p-nitrophenol compared to the commercial RANEY® Ni. The catalytic activity of nickel particles prepared in the presence of composite modifiers was higher than nano nickel catalysts prepared in the presence of single modifiers. The magnetic property, possible catalytic mechanism and the possibility of reusability were also investigated.

Two-Dimensional CaIn2S4/g-C3N4 Heterojunction Nanocomposite with Enhanced Visible-Light Photocatalytic Activities: Interfacial Engineering and Mechanism Insight

Design and exploitation of efficient visible light photocatalytic systems for water splitting and degradation of organic dyes are of huge interest in the fields of energy conversion and environmental protection. Herein, two-dimensional CaIn2S4/g-C3N4 heterojunction nanocomposites with intimate interfacial contact have been synthesized by a facile two-step method. Compared with pristine g-C3N4 and CaIn2S4, the CaIn2S4/g-C3N4 heterojunction nanocomposites exhibited significantly enhanced H2 evolution and photocatalytic degradation of methyl orange (MO) activities under visible light irradiation. The optimal CaIn2S4/g-C3N4 nanocomposite shows a H2 evolution rate of 102 μmol g(-1) h(-1), which is more than 3 times that of pristine CaIn2S4. The mechanisms for improving the photocatalytic performance of the CaIn2S4/g-C3N4 nanocomposites were proposed by using the photoluminescence measurement and electrochemical analyses. It was demonstrated that the enhanced photocatalytic performance of CaIn2S4/g-C3N4 heterojunction nanocomposites mainly stems from the enhanced charge separation efficiency. In addition, a plausible mechanism for the degradation of MO dye over CaIn2S4/g-C3N4 nanocomposites is also elucidated using active species scavengers studies.

Highly efficient heterojunction photocatalyst based on nanoporous g-C3N4 sheets modified by Ag3PO4 nanoparticles: synthesis and enhanced photocatalytic activity.

Novel visible-light-driven heterojunction photocatalyst composed by Ag3PO4 nanoparticles and nanoporous graphitic carbon nitride sheets (Ag3PO4/p-g-C3N4) was synthesized by a facile and green method. The results showed that photocatalytic activity of Ag3PO4/p-g-C3N4 was much higher than that of pure p-g-C3N4 in the photodegradation of Rhodamine B under visible light irradiation. The kinetic constant of Rhodamine B degradation over Ag3PO4 (33.3 mol%)/p-g-C3N4 was about 5 and 2 times higher than that over pure p-g-C3N4 and Ag3PO4, respectively. The enhanced photocatalytic performance is attributed to the stronger visible light absorption and the heterojunction between Ag3PO4 nanoparticles and p-g-C3N4, which could induce the low recombination rate of photoinduced electron-hole pairs.

Facile route fabrication of nano-Ni core mesoporous-silica shell particles with high catalytic activity towards 4-nitrophenol reduction

A facile, environmentally friendly synthetic route was developed to prepare nano-Ni core mesoporous-silica shell particles. Ethylenediaminetetraacetic disodium salt (EDTA) was the chelating agent and thus controlled the nucleation rate of the nano-Ni core. In this work, EDTA was used to regulate the reduction rate of nickel acetate. Thereby, by varying the amount of EDTA utilized in reaction medium, the size of nano-Ni can be readily controlled in the range of 40–80 nm. The mesoporous silica shell was fabricated by the Stober method. The nano-Ni core mesoporous-silica shell particles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). UV spectrophotometry (UV/vis) was used to analyse the growth mechanism of the nano-Ni cores. The as-synthesized nano-Ni core mesoporous silica shell particles were found to show a good catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol in the presence of an excess amount of NaBH4. The magnetic properties, catalytic mechanism and the possibility of reusability were also investigated.

Hydrothermal synthesis of In2S3/g-C3N4 heterojunctions with enhanced photocatalytic activity.

Graphitic carbon nitride (g-C3N4) was hybridized by In2S3 to form a novel In2S3/g-C3N4 heterojunction photocatalyst via a hydrothermal method. TEM and HRTEM results reveal that In2S3 nanoparticles and g-C3N4 closely contact with each other to form an intimate interface. The as-obtained In2S3/g-C3N4 heterojunctions exhibit higher photocatalytic activity than those of pure g-C3N4 and In2S3 for the photodegradation of rhodamine B (RhB) under visible light irradiation. The enhanced photocatalytic performance of In2S3/g-C3N4 heterojunctions could be attributed to its wide absorption in the visible region and efficient electron-hole separation. On the basis of radical scavenger experiments, superoxide radicals and holes are suggested to play a critical role in RhB degradation over In2S3/g-C3N4 heterojunctions.

In-situ ion exchange synthesis of hierarchical AgI/BiOI microsphere photocatalyst with enhanced photocatalytic properties

Novel hierarchical AgI/BiOI microspheres were synthesized using a facile in situ ion exchange reaction between BiOI microspheres and a AgNO3 solution. The results show that the AgI nanoparticles sre uniformly anchored on the surface of the BiOI nanosheets. The optimal amount of AgI in a AgI/BiOI microsphere was found to be 70.4%. The degradation rate of RhB over a 70.4% AgI/BiOI heterojunction was found to be 7.8 and 3.0 times higher than that of bare BiOI and AgI, respectively. The degradation rate of phenol over a 70.4% AgI/BiOI heterojunction was found to be 95.4%, which is 2.9 and 14.2 times higher than that of bare BiOI and AgI, respectively. The enhanced photocatalytic activity induced by the in situ grown AgI nanoparticles is attributed to the effective electron–hole separation between BiOI and AgI.

Natural leaves-assisted synthesis of nitrogen-doped, carbon-rich nanodots-sensitized, Ag-loaded anatase TiO2 square nanosheets with dominant {001} facets and their enhanced catalytic applications

Extending the UV response of anatase TiO2 photocatalysts into the visible light range can play a pivotal role in promoting the practical applications of these catalysts. Nitrogen and carbon co-doped, silver loaded anatase TiO2 (Ag@NC–TiO2) single-crystal nanosheets dominated by {001} facets were prepared for the first time using leaves as the nitrogen and carbon source by a facile, low cost method. The size of the Ag particles on NC–TiO2 nanosheets can be tuned from 1.5 nm to 15 nm using a photo-reduction strategy. The synthesized Ag@NC–TiO2 nanosheets show higher photocatalytic activity in the photodecomposition of organic pollutants compared to NC–TiO2, TiO2 and P25 under visible light irradiation. The enhanced photocatalytic efficiency was ascribed to a synergistic effect between N, C and Ag. In addition, the formed Ag@NC–TiO2 heteronanosheets are highly dispersible in aqueous solution and are capable of efficient catalysis for the reduction of p-nitrophenol. The present synthesis gives a promising method of forming non-metal co-doped, metal nanoparticles (NPs) loaded anatase TiO2 with dominant {001} facets and for broad applications in catalysis and photocatalysis.

Controlled synthesis of Bi2S3/ZnS microspheres by an in situ ion-exchange process with enhanced visible light photocatalytic activity

A novel Bi2S3/ZnS heterostructure has been synthesized through an in situ cation-exchange method between ZnS and bismuth(III) chloride. The obtained samples were characterized by multiform techniques, such as X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission microscopy, UV-visible diffuse-reflectance spectroscopy, and photoluminescence spectra. The photocatalytic activities of the obtained photocatalysts were measured by the degradation of rhodamine B (RhB) and refractory oxytetracycline (OTC) under visible-light irradiation (λ ≥ 400 nm). The as-prepared Bi2S3/ZnS photocatalysts exhibit wide absorption in the visible-light region and display superior visible-light-driven photocatalytic activities in degradation of RhB and OTC compared with pristine ZnS microspheres and Bi2S3 nanorods. The dramatic enhancement in the visible light photocatalytic performance of the Bi2S3/ZnS composites could be attributed to the effective electron-hole separations at the interfaces of the two semiconductors, which facilitate the transfer of the photoinduced carriers. The present study provides helpful insight into the design of novel and highly efficient sulfate heterostructure photocatalysts.

N-doped graphene quantum dots as an effective photocatalyst for the photochemical synthesis of silver deposited porous graphitic C3N4 nanocomposites for nonenzymatic electrochemical H2O2 sensing

In this work, nitrogen-doped graphene quantum dots (N-GQDs) were proved to be an efficient photocatalyst for photochemical synthesis of Ag nanoparticle loaded porous graphitic C3N4 (p-g-C3N4) for the first time. The Ag nanoparticles were well-formed in high yield and closely anchored at the surface of p-g-C3N4 with uniform size distribution. Importantly, the as-prepared Ag/p-g-C3N4 nanocomposites exhibited excellent catalytic activity towards electrocatalytic reduction of hydrogen peroxide (H2O2). The cyclic voltammetry and amperometry results show that the sensor of the as-prepared Ag/p-g-C3N4 composite exhibits excellent analytical response to H2O2 with fast response, wide linear range and low detection limit.

Shape-controlled synthesis of F-substituted hydroxyapatite microcrystals in the presence of Na2EDTA and citric acid.

We present a facile strategy for the shape-controlled synthesis of F-substituted hydroxyapatite (FHAp) microcrystals based upon using a combination of Na(2)EDTA and citric acid (CA). Novel, well-defined FHAp microcrystals of various shapes, such as hexagonal disks with predominant (0 0 0 1) faces, hexagonal shuttles, hexagonal prisms, icosahedrons, and hexagonal microrods with tunable aspect ratios, were fabricated. In particular, FHAp hollow microcrystals with tunable shapes were fabricated directly without using any additional template. The central features of our approach are the use of both Na(2)EDTA and CA as two distinct chelating reagents and the use of substitution ions (F(-)) itself as a growth inhibitor for the FHAp crystals. F(-) ions were found to play a critical role in the formation of hexagonally shaped FHAp microcrystals, and in the one-pot formation of hollow microcrystals, which relies on the addition order of F(-) ions in the synthesis.