Liangjie Yuan

Zn(II)-PEG 300 Globules as Soft Template for the Synthesis of Hexagonal ZnO Micronuts by the Hydrothermal Reaction Method

Hexagonal ZnO micronuts (HZMNs) have been successfully synthesized with the assistance of poly(ethylene glycol) (PEG) 300 via a hydrothermal method. The structure and morphology of the HZMNs were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). An individual ZnO micronut is revealed as twinned crystals. Time-dependent investigation shows that the growth of HZMNs involves a dissolution-recrystallization process followed by Ostwald ripening, in which is the first formed solid ZnO particles dissolve and transform to HZMNs with hollow structure. PEG 300 has been found to play a crucial role in the growth of this unique hollow structure. TEM observations show that the PEG chains aggregate to globules in water, which then have interaction with the dissolved zinc species to form the globules in a coiled state under hydrothermal conditions. These Zn(II)-PEG 300 globules act as soft template for the growth of HZMNs, and the possible growth mechanism is proposed. The room-temperature photoluminescence (PL) spectrum shows red emission around 612 nm with a full width at half-maximum (fwhm) only about 13 nm.

Synthesis of core–shell SiO2@MgO with flower like morphology for removal of crystal violet in water

In this study, we report a facile and effective route to synthesize core-shell SiO2@MgO with flower like morphology, which the shell is assembled by magnesium oxide nanosheets. The SiO2@MgO composite (SMC) was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), X-ray fluorescence (XRF) and N2 adsorption-desorption techniques. The sample showed excellent performance for the removal of crystal violet due to its high specific surface area and porous structures. Adsorption data fitted better with Langmuir isotherm and the maximum adsorption capacity was 2244.85 mg g(-1). The kinetic data was better described by pseudo-second order model and thermodynamic studies showed that adsorption process was spontaneous and endothermic. The adsorbent also showed very good reproducibility and reusability for the successive five cycles, indicating a promising potential material for environmental remediation.

Micro/nano-structured polyaniline/silver catalyzed borohydride reduction of 4-nitrophenol

Micro/nano-structured polyaniline/silver (PANI/Ag) composites have been prepared by simply mixing nitric acid doped polyaniline with silver nitrate. A reducing agent was added to accelerate the reaction process and enhance the conversion rate of silver nitrate. As the support material of silver nanoparticles, nitric acid doped polyaniline was synthesized under turbulent flow and surfactants were adopted to control the morphology and uniformity of the particles. Various analysis techniques were adopted to confirm the composition and structure of the composites, including scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTIR) and energy dispersive X-ray analysis (EDX). The PANI/Ag particles were used as a catalyst in the borohydride reduction reaction of 4-nitrophenol (4-NP), which was online monitored by UV-vis absorption spectroscopy. Results demonstrated that PANI microspheres loaded with 18.30 wt% of silver showed a comparable catalytic performance, and the apparent rate constant is 0.0256 s−1. Moreover, the stability and reusability of the catalyst were also investigated. The present work highlights the incorporation of well-dispersed silver nanoparticles with the conductive polyaniline matrix, and the accelerated electron transfer during the catalytic process owing to the high electrical conductivity of the support material.

Supramolecular hydrogen bond framework constructed by 1-aminoethylidenediphosphonic acid and monovalent ions: Li + , Na + , and

Four new monovalent 1-aminoethylidenediphosphonates, [Li(AEDPH3)(H2O)]6 (1), Na2(AEDPH3)2(H2O)8 (2), (NH4)(AEDPH3) (3) and ((CH3)2NH2)(AEDPH3)(H2O) (4) have been synthesized and characterized by elemental analysis, IR, TG together with X-ray single crystal diffraction analysis. Compound 1 is a 24-metallacrown-6 lithium structure, compound 2 is binuclear Na+ bridged by water molecules, and compounds 3 and 4 are proton-transfer salts. All four compounds are further extended to form three-dimensional (3D) supramolecular structures with the aid of water molecules (excluding 3) via various predictable hydrogen bonds.

Self-assembly of organic acid–base compounds from 2-D layered network to 3-D supramolecular framework: synthesis, structure and photoluminescence

The reactions of organophosphonic acids [1-aminoethylidenediphosphonic acid (AEDPH4), 1-aminopropane-1,1,3-triphosphonic acid (APTPH6)] and 2,2′-bipyridyl-like ligands [2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen)] under low temperature hydrothermal conditions yielded four acid–base compounds, namely, (AEDPH3)·(H2bipy)1/2·2H2O (1), (AEDPH3)·(Hphen)·2H2O (2), (APTPH5)·(Hbipy)·2H2O (3) and (APTPH4)·(Hphen)·(H3O)·3H2O (4). These four compounds were characterized by a single crystal X-ray diffraction method, elemental analysis (EA), infrared spectrometry (IR) and thermogravimetric analysis (TGA). They all crystallize in a triclinic system, with a P space group. In particular, the supramolecular structures of organophosphonic acids in these four compounds are different. In compounds 1 and 2, the dimer or dimer chains are formed by hydrogen bonds between adjacent phosphonate groups, while in compounds 3 and 4 two-dimensional (2-D) layered networks are constructed by the hydrogen bonds between the phosphonate groups. The diversity of supramolecular structures is due to the difference of AEDPH4 and APTPH6 ligands. Additionally, their luminescence in the solid state has also been studied at room temperature.

Hydrogen-bonded assembly of aminophosphonic anions: different 1D, 2D and 3D supramolecular architectures

In order to investigate hydrogen-bonded assembly of aminophosphonic anions, six novel organic acid–base compounds including (AEDPH2)·(1,3-pnH2)·H2O (1), (AEDPH2)·(1,2-pnH2)·H2O (2), (AEDPH2)·(pipH2)·H2O (3), (AEDPH3)·(pipH2)0.5·3H2O (4), (APDPH3)·(pipH2)0.5 (5) and (APDPH3)·(enH2)0.5 (6), as well as hydrate compounds (AEDPH3)·H3O (7) and (APDPH3)·H3O (8) (AEDPH4 = 1-aminoethylidenediphosphonic acid, APDPH4 = 1-aminopropane-1,1-diphosphonic acid, 1,2-pn = 1,2-propylenediamine, 1,3-pn = 1,3-propylenediamine, pip = piperazin, en = ethylenediamine), were synthesized and characterized. The aminophosphonic acids in these compounds are deprotonated to form anions with different valences and show various structural aggregates: The AEDPH22− anions form one-dimensional (1D) zigzag supramolecular chains with different chain lengths and angles in compounds 1 and 2, while create 1D linear double supramolecular chain in compound 3. The monovalent aminophosphonic anions generate two-dimensional (2D) supramolecular layers with different layer to layer distances in compounds 4–6, but display 3D supramolecular framework in compounds 7 and 8. In particular, compound 4 contains a 1(1)3(1)R4 water cluster. The factors which influence hydrogen-bonded assembly of aminophosphonic anions, including structure of diamine, C: A ratio and substitutional group of aminophosphonic acid, are all discussed in detail.

SiO2@Ag/AgCl: a low-cost and highly efficient plasmonic photocatalyst for degrading rhodamine B under visible light irradiation

A series of highly efficient and low cost visible light-driven micro/nano-structure photocatalysts, composed of microstructure SiO2 spheres and Ag/AgCl nanocomposites with different proportion of AgCl to Ag, have been facilely and controllably fabricated via deposition–precipitation method and in situ oxidation process. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra (UV-vis-DRS). The as-prepared photocatalysts exhibit wide absorption in the visible light region and display superior photocatalytic activity and excellent stability towards degradation of organic pollutants, i.e., rhodamine B (RhB) compared with commercial TiO2 (P25) and pure Ag/AgCl under visible light (λ ≥ 420 nm). Furthermore, the molar ratio of AgCl to Ag in the SiO2@Ag/AgCl composites has an important effect on their photocatalytic performance. The possible mechanism for the enhancement in decomposition of RhB molecules under visible light irradiation is discussed. This work may provide new insights into the fabrication of visible light-driven photocatalysts with low cost and excellent performance and facilitate their practical application in environmental issues.

Synthesis and structures of three triphosphonate compounds containing d10 transition metal ions

Three new triphosphonate compounds, [Zn(APTPH4)(2,2′-bipy)(H2O)] · 2H2O (1), [Cd(APTPH4)(2,2′-bipy)(H2O)] · 2H2O (2), and [Zn(APTPH4)(phen)2] · phen · 4H2O (3) (APTPH6 = 1-aminopropane-1,1,3-triphosphonic acid, 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline), are synthesized by a low-temperature hydrothermal method. Compounds 1 and 2 are isomorphous, both one-dimensional (1D) coordination polymers expanded into three-dimensional (3D) supramolecular structures by hydrogen bonds and π–π stacking interactions. Compound 3 is a molecular complex and forms a 3D network through an S-shaped water hexamer. Crystal data for 1: Triclinic, space group P 1, a = 6.6814(5) Å, b = 10.0929(7) Å, c = 15.438(2) Å, α = 81.544(2)°, β = 79.066(2)°, γ = 82.278(2)°, Z = 2; for 2: Triclinic, space group P 1, a = 6.9380(8) Å, b = 10.043(2) Å, c = 15.681(2) Å, α = 81.357(2)°, β = 78.510(2)°, γ = 81.902(2)°, Z = 2; Crystal data for 3: Triclinic, space group P 1, a = 12.540(2) Å, b = 12.596(2) Å, c = 14.997(2) Å, α = 100.795(2)°, β = 113.328(2)°, γ = 101.358(2)°, Z = 2.

Hydrogen-bonded assembly of [Ni(Im)6]2+ ion and phosphorus anions: Different sandwiched-type/tessellate-type supramolecular architectures and 1D water chains

Four new [Ni(Im)6]2+-phosphorus compounds, namely, [Ni(Im)6](PO4)·ImH·4 H2O (1), [Ni(Im)6][Ni(AEDPH)(Im)3]2 (2) [Ni(Im)6][Ni(AEDP)(Im)3]·Im·3 H2O (3), [Ni(Im)6][Ni(Im)3(APTPH)]·Im·ImH·8 H2O (4), (AEDPH4 = 1-aminoethylidenediphosphonic acid, APTPH6 = 1-aminopropane-1,1,3-triphosphonic acid), are synthesized and characterized. These compounds illustrate various three-dimensional (3D) supramolecular structures. Compounds 1 and 2 both contain a two-dimensional (2D) packing arrangement of [Ni(Im)6]2+ ions however they feature different sandwich-type structures: in 1, PO43− ions and ImH+ ions are self-assembled to form a one-dimensional (1D) zigzag supramolecular chain; while a 2D pillared layer structure is generated by the interconnection of [Ni(AEDPH)(Im)3]− ions in 2. Compounds 3 and 4 both comprise a 1D packing arrangement of [Ni(Im)6]2+ ions however they form dissimilar tessellate-type architectures: in 3, 1D double chain structure is constructed by [Ni(AEDPH)(Im)3]2− ions and Im molecules, whereas in 4, [Ni(Im)3(APTPH)]3− ions, Im molecules and ImH+ ions are integrated to generate a 3D supramolecular network with extended 1D channels. Moreover, compounds 1, 3 and 4 all contain diverse 1D water chain structures: C8 helix water chain in 1, C4 zigzag water chain in 3, and 1(1)8(1)C14 wavelike water chain in 4. The effects of phosphorus counterions on the structural types of the final products, as well as the hydrogen bond motifs, are also discussed in detail.

Novel SiO2@MgxSiyOz composite with high-efficiency adsorption of Rhodamine B in water

A series of core–shell SiO2@MgxSiyOz (SM) composites were synthesized with high efficiency for the adsorption of Rhodamine B (RhB). The composites were characterized by powder X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and nitrogen adsorption–desorption. The influences of different magnesium oxide additions, adsorbent dosage, temperature, contact time and initial RhB concentration on RhB adsorption were investigated, and the optimized adsorption parameters were also obtained. The adsorption data was evaluated using Langmuir and Freundlich models, but high correlation coefficients (R2) confirmed the validity of the Langmuir isotherm, with maximum adsorption capacity of 52.71 mg g−1 at 313 K. The kinetic data fitted a pseudo-second order model well and thermodynamic studies showed that the adsorption process was spontaneous and endothermic. Even after five successive cycles for the adsorption–desorption of RhB, the regenerated powders retained excellent adsorption capacity with more than 99% dye removal and could be utilized as an efficient and low-cost adsorbent for adsorption of RhB dye in wastewater.