Co-reporter:Feng Yang;Daohua Sun;Qingbiao Li;Xiaolian Jing
Industrial & Engineering Chemistry Research May 27, 2015 Volume 54(Issue 20) pp:5373-5380
Publication Date(Web):Publication Date (Web): April 29, 2015
DOI:10.1021/ie5047363
In the biorefining process, polyols are important intermediates, and the oxidation of polyols toward other value added products is of great significance. This work describes a green and facile biosynthesis method for the preparation of Ag/ZrO2 catalyst for selective oxidation of 1,2-propanediol (a typical polyol). Cinnamomum comphora (CC) leaf extract was employed as the reducing and capping agent for the preparation of Ag nanoparticles (NPs) with the assistance of microwave irradiation. The main reducing agents were identified as polyphenols by Fourier transform infrared spectroscopic analysis of CC extracts before and after reaction. After electrostatic adsorption, the NPs were anchored onto the support ZrO2. The Ag/ZrO2 catalysts were found with good dispersity and showed excellent activity toward selective oxidation of 1,2-propanediol. The effects of the preparation conditions on catalyst activity were studied; the optimal condition was obtained (microwave time of 4 min, CC concentration of 12 g/L and Ag loading of 5%). Since the natural capping agents are easy to remove, the catalysts need no calcination treatment before catalytic reaction. Thus, the microwave-assisted biosynthesis appears to be environmentally benign as neither expensive chemicals nor intensive energy consumption is engaged.
Co-reporter:Tareque Odoom-Wubah, Zhenzhen Li, Zhou Lin, Tingting Tang, Daohua Sun, Jiale Huang, Qingbiao Li
Electrochimica Acta 2017 Volume 228(Volume 228) pp:
Publication Date(Web):20 February 2017
DOI:10.1016/j.electacta.2017.01.107
•Plant-mediated synthesis of porous Pd-Pt alloy NFs with dominant (111) planes.•The biogenic Pd-Pt NFs were used directly in ethanol oxidation without special treatment.•The PdPt3 NFs is 4.1, and 9.1 more active than commercial Pd and Pt–black toward ethanol oxidation.•Electrocatalytic activity increased with Pt content, and stability with Pd additionBimetallic Pd-Pt nanoflowers (Pd-Pt NFs) of varying sizes (20–60 nm) were synthesized through the concurrent reduction of Pd(NO3)2 and K2PtCl4 using Cinnamomum camphora (C. camphora) leaf extract assisted by ascorbic acid (AA). C.Camphora acted as both a co-reducing agent and a green template in the synthesis protocol providing a fast, simple, green and cost-effective means of producing the Pd-Pt NFs. Characterization techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to confirm the Pd-Pt NFs formation. FT-IR analysis showed that biomolecules such as polyphenols and flavonoids were responsible for the reduction while stretching vibration bands from CH, CC, OH, and CO O acted as capping agents. The as-formed Pd-Pt NFs showed excellent performance and stability in the electro-oxidation of ethanol in alkaline media. Electro-catalytic performance increased with Pt content, while addition of Pd increased stability. The PdPt3 NFs presented the best performance with a mass activity of 1.43 A mg−1metal, 5.72, 4.93, 2.27, 1.27, 11 and 4.6% higher than the Pd, Pt, Pd3Pt, and PdPt NFs, and commercial Pt and Pd-black respectively. However, it was more prone to poisoning, with an If/Ir value of 0.78 compared to 1.37 for Pd3Pt NFs.
Co-reporter:Xiaoming Peng, Fengping Hu, Jiale Huang, Yajun Wang, Hongling Dai, Zhanmeng Liu
Microporous and Mesoporous Materials 2016 Volume 228() pp:196-206
Publication Date(Web):1 July 2016
DOI:10.1016/j.micromeso.2016.03.047
•Pitch resin is a promising precursor for mesoporous carbon synthesis.•The adsorption of CIP increased with the increase of their neutral or zwitterionic formed on the adsorbents.•Three-parameter isotherm models shows better fit to Langmuir adsorption data.A graphitic ordered mesoporous carbon (OMC) was fabricated by a nanocasting process by using silica SBA-15 as a template and pitch resin as carbon precursor. The modification and application of the OMC for Ciprofloxacin (CIP) removal from the aqueous solution were investigated. The results exhibited that the OMC modified with different chemical agent were more efficient than the unmodified one. The CIP adsorption increased with the increase of their neutral (CIP0) or zwitterionic (CIP±) formed on the adsorbents because of hydrophobic effect. The adsorption amount of CIP onto the adsorbents increased with NaCl concentration. The data was analyzed by the Langmuir, Freundlich and Temkin isotherms. The results indicated that adsorption of CIP onto the four adsorbents fitted better with the Langmuir model. The adsorption process follows pseudo second-order kinetic model. The results of the present study suggested that the original and modified OMC were effective sorbents for removal of antibiotics from aqueous solutions.
Co-reporter:Tareque Odoom-Wubah;Williams B Osei;Xiaoer Chen;Daohua Sun;Qingbiao Li
Journal of Chemical Technology and Biotechnology 2016 Volume 91( Issue 5) pp:1493-1504
Publication Date(Web):
DOI:10.1002/jctb.4748
ABSTRACT
BACKGROUND
The synthesis and application of novel zinc micro/nanostructures are of increasing importance in modern nanotechnology.
RESULTS
This paper reports the large scale synthesis of zinc oxide micro-flowers (ZnOMFs) using precipitation assisted by Cinnamomum camphora leaf extract (C. camphora) at relatively low temperatures ≤ 80°C. The results showed that the ZnOMFs consisted of several nanoplates connecting together in the presence of the leaf extract which acted as a modifying, capping and stabilizing agent. X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM), energy dispersed X-ray and photoluminescence studies were used to characterize and verify the nature of the ZnOMFs. Varying the leaf extract amount (5 to 20 mL) fine-tuned the morphology of the as-formed zinc oxide microstructures (ZnOMS). The as-formed ZnOMFs showed high photocatalytic activity for the degradation of methyl orange dye under ultraviolet (UV) irradiation, achieving 100% degradation after 45 min of reaction.
CONCLUSION
The use of leaf extract as a bio-template and capping agent provided an effective, cheaper and more environmentally benign way of controlling and directing the shape of as-formed ZnO microstructure. © 2015 Society of Chemical Industry
Co-reporter:Mingming Du;Xiaolian Jing;Daohua Sun;Qingbiao Li
Journal of Chemical Technology and Biotechnology 2016 Volume 91( Issue 7) pp:2125-2130
Publication Date(Web):
DOI:10.1002/jctb.4815
Abstract
BACKGROUND
Au valence for Au catalysts has been considered a vital parameter for catalytic activity towards CO oxidation. However, there is no effective method to prepare precise Au0/Auδ+ molar ratios with the same Au nanoparticles (NPs) sizes.
RESULTS
A series of Au/TiO2 catalysts with tuneable Au0/Auδ+ molar ratios were prepared by the combination of a biosynthesis method and a deposition–precipitation (DP) method, and characterized by XPS, TEM, DRUV-Vis techniques. First, biosynthesized metallic Au NPs were immobilized onto TiO2 supports to obtain Au/TiO2 catalysts with different Au loadings but with the same sized Au NPs. And then positively ionized Au species were supported onto the above Au/TiO2 catalysts by a DP method. The metallic Au and positively ionized Au species could be totally supported on the support. Therefore, the Au0/Auδ+ molar ratios could be controlled exactly. Compared with Au/TiO2 catalysts with metallic and positively ionized Au species alone, the catalyst Au/TiO2-1:1 showed the best initial catalytic activity, suggesting enhanced catalytic performance due to the coexistence of Au0 and Auδ+.
CONCLUSION
This study verifies that Au/TiO2 catalysts with accurate Au0/Auδ+ molar ratios can be prepared by a combination of biosynthesis and a DP method. © 2015 Society of Chemical Industry
Co-reporter:Mingming Du, Jiale Huang, Daohua Sun, Qingbiao Li
Applied Surface Science 2016 Volume 366() pp:292-298
Publication Date(Web):15 March 2016
DOI:10.1016/j.apsusc.2016.01.086
Highlights
- •
Interaction between Au and support surface is important for propylene epoxidation.
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Decreasing Au particles size can improve the catalytic performance.
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The Au catalysts showed high catalytic stability without deactivation during 100 h.
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Quick desorption of product from modified catalyst surface benefits to the stability.
Co-reporter:Huimei Chen, Jiale Huang, Dengpo Huang, Daohua Sun, Minhua Shao and Qingbiao Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 9) pp:4846-4854
Publication Date(Web):08 Jan 2015
DOI:10.1039/C4TA06226D
Exotic AuPd bimetallic nanoflowers (NFs) are facilely synthesized using a microorganism-mediated, cetyltrimethylammonium chloride (CTAC)-directed method at room temperature. The NFs consist of one-dimensional long pedicels and three-dimensional open horns. The effect of cell dosage and feed concentrations of ascorbic acid (AA), CTAC and metal precursors on the morphology of the bimetallic nanostructures were studied. The results showed that all the obtained materials were alloys with Pd-enriched surfaces. The diameters of the horns decreased, while those of the pedicels increased with increasing the feed concentration of Pd precursor. The presence of Pd precursor was vital for the formation of the nanowire part of the NF structure. Furthermore, the AuPd-NF/microorganism materials exhibited excellent catalytic performance and durability toward the hydrogenation of 1,3-butadiene.
Co-reporter:Xiaolian Jing;Dengpo Huang;Huimei Chen;Tareque Odoom-Wubah;Daohua Sun;Qingbiao Li
Journal of Chemical Technology and Biotechnology 2015 Volume 90( Issue 4) pp:678-685
Publication Date(Web):
DOI:10.1002/jctb.4353
Abstract
BACKGROUND
The synthesis and application of novel Au nanostructures are of increasing importance in modern nanotechnology.
RESULTS
Closely packed and chemically difficult-to-synthesize Au nanohorns (AuNHs) were synthesized in the presence of Escherichia coli cells (ECCs) and hexadecyltrimethylammonium chloride (CTAC) by a microorganism-mediated, CTAC-directed (MCD) approach. A proper ECC dosage, ascorbic acid (AA) and CTAC concentrations were essential for the growth of the AuNHs. In the formation mechanism of the AuNHs the ECCs surface acted as a platform for preferential nucleation and initial anisotropic growth of Au nanocrystals. As a result, some of the adjacent nanoparticles over the cell surface connected together via linear fusion to form dendritic nanostructures. Meanwhile, secondary nucleation in the solution gave rise to smaller nanoparticles that were consumed later on via Ostwald ripening during the formation of the AuNHs. Eventually, the two-dimensional film-like nanostructures between adjacent cells easily connected to form well-defined AuNHs with three-dimensional nanostructures. Interestingly, the AuNH/ECC composites can be used directly as sensitive surface-enhanced Raman spectroscopy (SERS) substrates for effective detection of 4-mercaptobenzoic acid (MBA).
CONCLUSION
The MCD strategy was an effective approach to novel AuNHs and AuNH/microorganism nanocomposites as SERS substrate. © 2014 Society of Chemical Industry
Co-reporter:Yingling Hong, Xiaolian Jing, Jiale Huang, Daohua Sun, Tareque Odoom-Wubah, Feng Yang, Mingming Du, and Qingbiao Li
ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 7) pp:1752
Publication Date(Web):June 9, 2014
DOI:10.1021/sc500181z
A green bioreductive approach with Cacumen Platycladi (CP) extract was adopted to fabricate bimetallic Au–Pd/TiO2 catalysts for solvent-free oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) with molar oxygen at atmospheric pressure. The Au–Pd nanoparticles (NPs) before being immobilized onto TiO2 were determined by transmission electron microscopy. And, the catalysts were further analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, etc. Effects of Au/Pd molar ratio, preparation conditions, and reaction conditions on the catalytic activity of Au–Pd/TiO2 were investigated. And, the Au–Pd/TiO2 catalyst without calcination that was prepared at 90 °C from the Au–Pd NPs with Au/Pd molar ratio of 2:1 exhibited excellent catalytic performance. With the catalyst, BzOH conversion of 74.2% and selectivity to BzH 95.8% were attained at the reaction temperature of 90 °C with an oxygen flow rate of 90 mL/min. Meanwhile, the recycling tests showed that, after seven recycles, the catalyst still remained with high conversion and selectivity. Therefore, the catalyst had excellent durability and reusability and good prospects for industrial application.Keywords: Benzyl alcohol; Bioreduction; Gold; Oxidation; Palladium;
Co-reporter:Huimei Chen, Dengpo Huang, Liqin Lin, Tareque Odoom-Wubah, Jiale Huang, Daohua Sun, Qingbiao Li
Journal of Colloid and Interface Science 2014 Volume 433() pp:204-210
Publication Date(Web):1 November 2014
DOI:10.1016/j.jcis.2014.07.038
•The adsorption rate of Pd (II) by P. pastoris increased after proper pretreatment.•The Pd NP/P. pastoris catalysts after pretreatment showed enhanced stability.•Slow reduction in Pd (II) with P. pastoris was essential for enhanced stability.Based on rapid adsorption and incomplete reduction in Pd (II) ions by yeast, Pichia pastoris (P. pastoris) GS115, the effects of pretreatment on adsorption and reduction of Pd (II) ions and the catalytic properties of Pd NP/P. pastoris catalysts were studied. Interestingly, the results showed that the adsorption ability of the cells for Pd (II) ions was greatly enhanced after they were pretreated with aqueous HCl, aqueous NaOH and methylation of amino group. For the reduction in the adsorbed Pd (II) ions, more slow reduction rates by pretreated P. pastoris cells were displayed compared with the cells without pretreatment. Using the reduction of 4-nitrophenol as a model reaction, the Pd NP/P. pastoris catalysts based on the cells after pretreatment with aqueous HCl, aqueous NaOH and methylation of amino group exhibited higher stability than the unpretreated cells. The enhanced stability of the Pd catalysts can be attributed to smaller Pd NPs, better dispersion of the Pd NPs, and stronger binding forces of the pretreated P. pastoris for preparing the Pd NPs. This work exemplifies enhancing the stability of Pd catalysts through pretreatments.
Co-reporter:Haixian Yang;Mingming Du;Tareque Odoom-Wubah;Jing Wang;Daohua Sun;Qingbiao Li
Journal of Chemical Technology and Biotechnology 2014 Volume 89( Issue 9) pp:1410-1418
Publication Date(Web):
DOI:10.1002/jctb.4225
Abstract
BACKGROUND
The facile use of microorganisms as green templates for shape-control of Au nanostructures can not only utilize their characteristic nanoscale dimensions and versatility, but also bridge the gap between bulk materials and Au nanostructures for technical applications.
RESULTS
Using Escherichia coli cells (ECCs), closely packed, hierarchically branched, chemically difficult-to-synthesize and stable Au nanowires (AuNWs) were fabricated through a seedless microorganism-mediated, hexadecyltrimethylammonium bromides (CTAB)-directed method. The ECCs played dual roles in the biosorption of Au ions and acted as preferential nucleation sites for Au nanocrystals in the formation of the AuNWs. In addition, proper CTAB concentration and just a little excessive ascorbic acid were essential to the formation of the AuNWs. The preferential nucleation sites that were simultaneously mediated by adjacent cells favored branched growth. Random growth of the same nanowire with multiple branched points gave rise to hierarchically branched AuNWs. Interestingly, the AuNW/ECC nanocomposites exhibited a noticeable absorbance at around 1900 nm in the near-infrared (NIR) region.
CONCLUSION
This study verifies the general strategy by combining a microorganism and CTAB for the fabrication of functional AuNW/microorganism nanocomposites. © 2013 Society of Chemical Industry
Co-reporter:Xianxue Li;Tareque Odoom-Wubah;Huimei Chen;Xiaolian Jing;Bingyun Zheng
Journal of Chemical Technology and Biotechnology 2014 Volume 89( Issue 12) pp:1817-1824
Publication Date(Web):
DOI:10.1002/jctb.4259
Abstract
BACKGROUND
Biosynthesis of Ag nanoparticles (AgNPs) utilizing renewable materials and nontoxic chemicals has become highly desirable and is currently receiving tremendous attention. In this study, a facile and cellulose-based approach was developed to biosynthesize AgNPs through tandem hydrolysis of silver sulfate and cellulose under hydrothermal conditions.
RESULTS
Well-defined AgNPs of about 72.0 nm in size were biosynthesized with 0.30 g of cellulose at 200°C for 10 h. The particle sizes of the as-synthesized AgNPs were positively affected by the reaction temperature and time, but on the contrary were negatively affected by the amount of cellulose employed. The results from Fourier transform infrared spectroscopy showed that the cellulose-hydrolyzed products (saccharides or aldehydes) were accountable for the bioreduction of the Ag ions, and the C = O (C–O) groups in the aldehydes or saccharides played critical roles in capping the AgNPs. Additionally, in the presence of the as-synthesized AgNPs, enhanced surface fluorescence of methyl orange was achieved.
CONCLUSION
A biological and maneuverable strategy was successfully developed for the synthesis of AgNPs by a hydrothermal route through tandem hydrolysis of silver sulfate and cellulose. Thus, this environmentally friendly method is anticipated to be utilized for the biosynthesis of AgNPs and opens up avenues to prepare other metal nanoparticles from metal sulfates. © 2013 Society of Chemical Industry
Co-reporter:Haixian Yang, Liqin Lin, Tareque Odoom-Wubah, Dengpo Huang, Daohua Sun, Jiale Huang, Qingbiao Li
Separation and Purification Technology 2014 Volume 133() pp:380-387
Publication Date(Web):8 September 2014
DOI:10.1016/j.seppur.2014.07.016
•Au recovery was enhanced by the coordination of cell-CTAB–ascorbic acid.•Au can be rapidly recovered by separating the precipitate from H2O.•CTAB and AA concentrations had no significant effect on the precipitation.•A trade-off existed between ECC-binding Au ion and ligand-substituted anion.In this paper, a microorganism-mediated, cetyltrimethylammonium bromide (CTAB)-directed (MCD) aggregation of Au nanostructures around Escherichia coli cells (ECCs) for enhanced Au recovery, from aqueous HAuCl4 is demonstrated for the first time. Owing to the coordination of cell-CTAB–ascorbic acid (AA), one dimensional Au nanostructures grew around the ECCs, inducing the rapid aggregation of Au and the ECCs. The concentrations of CTAB and AA had insignificant effect on the precipitation if the ECC dosage and HAuCl4 concentration were matched. The Au recovery efficiency decreased with increasing CTAB concentration, while a minimum AA concentration was required for higher Au recovery efficiency. The ECC-binding Au ions were reduced to form Au nuclei over the cell surface that provided preferential nucleation sites. Meanwhile, the free ligand-substituted anions in the solution were reduced to Au atoms that served as Au source for growing the Au nanostructures around the ECCs. This work exemplifies a new avenue to enhance the efficiency of recovering Au through the engineering of Au nanostructures.
Co-reporter:Huimei Chen, Jing Wang, Dengpo Huang, Xiaoer Chen, Jiajia Zhu, Daohua Sun, Jiale Huang, Qingbiao Li
Materials Letters 2014 Volume 122() pp:166-169
Publication Date(Web):1 May 2014
DOI:10.1016/j.matlet.2014.02.028
•A green approach to Ni nanoparticles (Ni NPs) by alfalfa extract was developed.•The Ni NP size could be tuned by adjusting the alfalfa extract concentration.•The flavonoids and reducing sugars were responsible for the reduction of Ni(II) ions.A facile and eco-friendly method for the preparation of sub-10 nm Ni nanoparticles (Ni NPs) has been developed based on the bioreduction of aqueous Ni(II) precursors with alfalfa extract. The XRD and XPS characterization results indicated the face-centered-cubic and zero-valent of Ni NPs, respectively. The size of the crystalline Ni NPs could be simply tuned by adjusting the concentration of alfalfa extract and strongly depended on the bioreduction of Ni(II). The biomolecular analyses of the extract also showed that flavonoids and reducing sugars played important roles in the bioreduction of Ni(II).
Co-reporter:Miao Wang, Tareque Odoom-Wubah, Huimei Chen, Xiaolian Jing, Tao Kong, Daohua Sun, Jiale Huang and Qingbiao Li
Nanoscale 2013 vol. 5(Issue 14) pp:6599-6606
Publication Date(Web):15 May 2013
DOI:10.1039/C3NR02290K
Closely packed, size-controllable and stable Au nanohorns (AuNHs) that are difficult to synthesize through pure chemical reduction are facilely synthesized using a microorganism-mediated method in the presence of hexadecyltrimethylammonium chloride (CTAC). The results showed that the size of the as-synthesized AuNHs could be tuned by adjusting the dosage of the Pichia pastoris cells (PPCs). The initial concentrations of CTAC, ascorbic acid (AA) and tetrachloroaurate trihydrate (HAuCl4·3H2O) significantly affected the formation of the AuNHs. Increasing the diameters of AuNHs led to a red shift of the absorbance bands around 700 nm in their UV-vis-NIR spectra. Interestingly, the AuNH/PPC composites exhibited excellent Raman enhancement such that rhodamine 6G with concentration as low as (10−9 M) could be effectively detected. The formation process of the AuNHs involved the initial binding of the Au ions onto the PPCs with subsequent reduction by AA to form supported Au nanoparticles (AuNPs) based on preferential nucleation and initial anisotropic growth on the platform of the PPCs. The anisotropic growth of these AuNPs, which was influenced by CTAC and PPCs, resulted in the formation of growing AuNHs, while the secondary nucleation beyond the PPCs produced small AuNPs that were subsequently consumed through Ostwald ripening during the aging of the AuNHs. This work exemplifies the fabrication of novel gold nanostructures and stable bio-Au nanocomposites with excellent optical properties by combining microorganisms and a surfactant.
Co-reporter:Bingyun Zheng, Tao Kong, Xiaolian Jing, Tareque Odoom-Wubah, Xianxue Li, Daohua Sun, Fenfen Lu, Yanmei Zheng, Jiale Huang, Qingbiao Li
Journal of Colloid and Interface Science 2013 Volume 396() pp:138-145
Publication Date(Web):15 April 2013
DOI:10.1016/j.jcis.2013.01.021
Pt nanoparticles (PtNPs) were biologically synthesized by reducing Na2PtCl4 with Cacumen Platycladi Extract (CPE). The effects of reaction temperature, initial Pt(II) concentration, and CPE percentage on Pt(II) conversion and the size distribution of the PtNPs were studied. The results showed that the Pt(II) conversion rate reached 95.9% and that PtNPs measuring 2.4 ± 0.8 nm were obtained under the following conditions: reaction temperature, 90 °C; CPE percentage, 70%; initial Pt(II) concentration, 0.5 mM; reaction time, 25 h. In addition, the bioreduction of Pt(II) was attributed to reducing sugars and flavonoids rather than proteins. The elucidation of bioreductive mechanism of Pt(II) ions was achieved by investigating the changes that occurred in the reducing sugar, flavonoid and protein concentrations in the plant extract, leading to a good insight into the formation mechanism of such biosynthesized PtNPs.Graphical abstractHighlights► A facile and green approach to Pt nanoparticles (PtNPs) was demonstrated. ► Effectiveness of the biosynthetic conditions for PtNPs was enhanced. ► The bioreductive mechanism of Pt(II) was elucidated.
Co-reporter:Xianxue Li, Bingyun Zheng, Tareque Odoom-Wubah, Jiale Huang
Ceramics International 2013 Volume 39(Issue 7) pp:7983-7988
Publication Date(Web):September 2013
DOI:10.1016/j.ceramint.2013.03.064
Abstract
Yttrium aluminum garnet (Y3Al5O12, YAG) precursor was synthesized by the co-precipitation method with ammonium hydrogen carbonate as the precipitant. The influence of aging and calcination temperature on the precursor composition and transformation temperature of the YAG phase was investigated. On that basis, a two-step sintering (TSS) method (heating the sample up to 1800 °C followed by holding it at 1600 °C for 8 h) was used to fabricate bulk transparent YAG ceramics in vacuum (10−3 Pa) in this communication. A variety of techniques, such as X-ray powder diffraction, infrared spectra, scanning electron microscopy and UV–vis–NIR spectrophotometry were adopted to characterize the resulting YAG powders and ceramics. The results showed that aging had a dramatic effect on the precursor composition, which in turn influenced the transformation temperature of the YAG phase. Loosely agglomerated YAG powders with a mean particle size of 50 nm were obtained by calcinating the precursor without aging at 1000 °C. Finally, a transparent YAG ceramic specimen, achieving the in-line transmittance of 41% in the visible wavelength region and a nearly pore-free microstructure with uniform grains of about 4 μm, was produced via the TSS technique.
Co-reporter:Lingfeng Wu, Weiwei Wu, Xiaolian Jing, Jiale Huang, Daohua Sun, Tareque Odoom-Wubah, Hongyu Liu, Haitao Wang, and Qingbiao Li
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 14) pp:5085
Publication Date(Web):March 18, 2013
DOI:10.1021/ie303518z
The synthesis and applications of anisotropic nanostructures have attracted much attention in modern nanotechnology. Recently, biosynthesis has been demonstrated to be a viable green alternative to traditional chemical and physical methods for synthesizing metal nanostructures. Herein, we developed a new, green one-pot synthetic protocol in which silver nanoflowers (Ag NFs) with three-dimensional structures were synthesized by Canarium album foliar broths in the presence of trisodium citrate (TSC) at room temperature. The effects of silver nitrate, TSC, and foliar broths on these synthesis processes were investigated to determine the optimum synthesis conditions. Further exploration of the formation mechanism of Ag NFs showed that both the biomolecules and TSC played very important roles. The improved insight into the specific roles of the bioprotective components and the controlled synthesizing ability are expected to help explain the formation mechanism of this interesting nanostructure that exhibited an excellent performance in surface-enhanced Raman scattering.
Co-reporter:Huimei Chen, Daohua Sun, Xinde Jiang, Xiaolian Jing, Fenfen Lu, Tareque Odoom-Wubah, Yanmei Zheng, Jiale Huang and Qingbiao Li
RSC Advances 2013 vol. 3(Issue 35) pp:15389-15395
Publication Date(Web):24 Jun 2013
DOI:10.1039/C3RA41215F
Synthesis of metal nanoparticles (NPs) is in the limelight in modern nanotechnology. In this present study, bimetallic Au/Pd NP/Pichia pastoris composites were successfully fabricated through a one-pot microbial reduction of aqueous HAuCl4 and PdCl2 in the presence of H2 as an electron donor. Interestingly, flower-like alloy Au/Pd NP/Pichia pastoris composites were obtained under the following conditions, NaCl concentration 0.9% (w/v), molar ratio of Au/Pd (1:2) and the time for pre-adsorption of Au(III) and Pd(II) ions 15 min, through fresh yeast reduction. The mapping results from scanning transmission electron microscopy (STEM) with a high-angle annular dark field detector confirmed that the Au/Pd NPs on the surface of the yeast were indeed alloy. Furthermore, the energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) measurements showed that the composition of the bimetallic NPs were consistent with the initial molar ratio of the precursors.
Co-reporter:Guowu Zhan, Yingling Hong, Fenfen Lu, Abdul-Rauf Ibrahim, Mingming Du, Daohua Sun, Jiale Huang, Qingbiao Li, Jun Li
Journal of Molecular Catalysis A: Chemical 2013 Volume 366() pp:215-221
Publication Date(Web):January 2013
DOI:10.1016/j.molcata.2012.09.026
In this paper, the kinetics and mechanism of oxidation of benzyl alcohol with H2O2 over heterogeneous bio-reduced Au/TS-1 catalysts have been reported after eliminating mass transfer resistances. Langmuir–Hinshelwood and power-law kinetic models are applied to describe the experimental results of the catalytic oxidation. By fitting the kinetic data using the power-rate law model, the orders of the reaction with respect to benzyl alcohol, H2O2, benzaldehyde and catalyst were found to be 0.55, 0.22, −0.35 and 1.06, respectively, with an activation energy of 38.2 kJ mol−1 from an Arrhenius plot. These fractional orders indicate that the species were adsorbed on the catalyst surface leading to the product, benzaldehyde. Furthermore, the reaction mechanism derived from the Langmuir–Hinshelwood model is proposed; it gives a reasonable description of the oxidation rate, following a rate expression:.r=0.0119×[BzOH][H2O2](1+2.222×[BzOH]+2.330×[H2O2]+4.769×[BzH])2 (mol L−1 gcat−1 s−1).Graphical abstractHighlights► A detailed kinetic study of benzyl alcohol oxidation with H2O2 has been reported. ► Mass transfer resistances were eliminated for estimating true kinetic parameters. ► The kinetic data was modeled using the power law rate expression. ► Reaction mechanism derived from Langmuir–Hinshelwood model was proposed. ► Rate expression describes satisfactorily the kinetic behavior of the reaction.
Co-reporter:Miao Wang, Tao Kong, Xiaolian Jing, Yu-Kao Hung, Daohua Sun, Liqin Lin, Yanmei Zheng, Jiale Huang, and Qingbiao Li
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 51) pp:16651
Publication Date(Web):November 30, 2012
DOI:10.1021/ie3026604
Au nanowire/Pichia pastoris cell composites were prepared using a microorganism-mediated method, where closely packed Au nanowires (AuNWs) are synthesized at high yields in the presence of hexadecyltrimethylammonium bromide (CTAB) without auxiliary seeds. The initial concentrations of ascorbic acid (AA), CTAB, and tetrachloroaurate trihydrate, as well as the amount of Pichia pastoris cells (PPCs), were optimized for the formation of AuNWs. For the formation of AuNWs, Au(III) ions were initially bound by the PPCs and then reduced by AA to produce Au nanoparticles (AuNPs) via preferential nucleation. The linear fusion of these AuNPs influenced by CTAB resulted in the formation of growing AuNWs, whereas the secondary nucleation beyond the PPCs produced small AuNPs that were subsequently consumed through Ostwald ripening during the aging of AuNWs. These AuNW/PPCs composites could be effectively used as surface-enhanced Raman scattering substrates for the detection of rhodamine 6G.
Co-reporter:Guowu Zhan, Mingming Du, Daohua Sun, Jiale Huang, Xin Yang, Yao Ma, Abdul-Rauf Ibrahim, and Qingbiao Li
Industrial & Engineering Chemistry Research 2011 Volume 50(Issue 15) pp:9019-9026
Publication Date(Web):June 21, 2011
DOI:10.1021/ie200099z
Au/TS-1 catalysts could be prepared by immobilizing the biosynthesized Au sol on TS-1 supports. A variety of techniques, such as N2 physisorption, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectorscopy, UV–visible diffuse reflectance, and thermogravimetric analysis, were employed to characterize both the supports and the bioreduction catalysts. The influence of various parameters (Si/Ti molar ratio, Au loading, immobilization pH, reaction temperature, and space velocity) on the catalytic performance in vapor phase propylene epoxidation with H2/O2 was systematically analyzed. Parameter optimization results manifested that the optimum catalytic activity and stability of bioreduction Au/TS-1 catalysts were obtained under optimum operation conditions of Si/Ti molar ratio of 35, Au loading of 1 wt %, immobilization pH of 2, reaction temperature of 573 K, and space velocity of 4000–8000 mL gcat–1 h–1. Furthermore, efforts were also made to clarify the plausible reaction routes over the bioreduction catalysts.
Co-reporter:Tareque Odoom-Wubah, Mingming Du, Williams Brown Osei, Daohua Sun, Jiale Huang, Qingbiao Li
Chinese Journal of Chemical Engineering (November 2015) Volume 23(Issue 11) pp:1907-1915
Publication Date(Web):1 November 2015
DOI:10.1016/j.cjche.2015.08.009
Microorganism-mediated, hexadecyltrimethylammonium chloride (CTAC)-directed (MCD) method was employed in this work to synthesize Pd nanoflowers (PdNFs). Proper Pichia pastoris cells (PPCs) dosage, ascorbic acid (AA), Pd(NO3)2 and CTAC concentrations were essential for the growth of the PdNFs. The size of the as-synthesized PdNFs could be tuned by adjusting the amount of Pd(NO3)2 solution and dosage of PPCs used. Characterization techniques such as X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to verify the nature of the PdNFs. Finally the PdNF/PPC nanocomposites were immobilized onto TiO2 supports to obtain bio-PdNF/TiO2 catalysts which showed excellent catalytic activity for CO oxidation, obtaining 100% conversion at 100 °C and remaining stable over a period of 52 h of reaction time.Download full-size image
Co-reporter:Mingming Du, Guowu Zhan, Xin Yang, Huixuan Wang, Wenshuang Lin, Yao Zhou, Jing Zhu, Ling Lin, Jiale Huang, Daohua Sun, Lishan Jia, Qingbiao Li
Journal of Catalysis (27 October 2011) Volume 283(Issue 2) pp:192-201
Publication Date(Web):27 October 2011
DOI:10.1016/j.jcat.2011.08.011
The direct vapor-phase epoxidation of propylene in the presence of hydrogen and oxygen was studied at a space velocity of 7000mLh-1gcat.-1 over gold catalysts with varying gold and titanium contents prepared by ionic liquid-enhanced immobilization (ILEI) method in which biosynthesized gold nanoparticles (GNPs) were immobilized onto the titanium silicalite-1 (TS-1) supports through the assistance of a small amount of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). The results showed that [BMIM]+ specially adsorbed onto the support to increase its isoelectric point, leading to the enhanced immobilization. The propylene conversion of 14.6% and PO formation rate of 164.4gpoKgcat.-1h-1 were higher than those in any other reports, probably attributing to enhanced interaction between the GNPs and TS-1. Furthermore, the excellent activity and high selectivity of the Au/TS-1 catalysts at a relatively high reaction temperature might be attributed to the existence of residual biomolecules on the catalysts.Graphical abstractBiosynthesized gold nanoparticles (GNPs) were immobilized onto TS-1 through 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). [BMIM]+ specially adsorbed onto the support to increase its isoelectric point, leading to the enhanced immobilization and high activity and stability for propylene epoxidation with H2/O2 mixture, probably attributing to enhanced interaction between the GNPs and TS-1 and the role of residual biomolecules in protecting the GNPs thereof.Download high-res image (45KB)Download full-size imageHighlights► The gold nanoparticles were prepared by biosynthesis method. ► Au nanoparticles were completely immobilized on TS-1 support with ionic liquid. ► Au/TS-1 catalysts exhibited high activity and stability for propylene epoxidation. ► About 4.6% of propylene conversion could be obtained. ► The isoelectric point of TS-1 could be changed by ionic liquid.
Co-reporter:Huimei Chen, Jiale Huang, Dengpo Huang, Daohua Sun, Minhua Shao and Qingbiao Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 9) pp:NaN4854-4854
Publication Date(Web):2015/01/08
DOI:10.1039/C4TA06226D
Exotic AuPd bimetallic nanoflowers (NFs) are facilely synthesized using a microorganism-mediated, cetyltrimethylammonium chloride (CTAC)-directed method at room temperature. The NFs consist of one-dimensional long pedicels and three-dimensional open horns. The effect of cell dosage and feed concentrations of ascorbic acid (AA), CTAC and metal precursors on the morphology of the bimetallic nanostructures were studied. The results showed that all the obtained materials were alloys with Pd-enriched surfaces. The diameters of the horns decreased, while those of the pedicels increased with increasing the feed concentration of Pd precursor. The presence of Pd precursor was vital for the formation of the nanowire part of the NF structure. Furthermore, the AuPd-NF/microorganism materials exhibited excellent catalytic performance and durability toward the hydrogenation of 1,3-butadiene.
