Co-reporter:Wenwu Liu, Huanyu Zhang, Hui-gang Wang, Mei Zhang, Min Guo
Applied Surface Science 2017 Volume 422(Volume 422) pp:
Publication Date(Web):15 November 2017
DOI:10.1016/j.apsusc.2017.06.007
•TiO2 nanowire arrays/Er-Yb codoped TiO2 nanoparticles were prepared on Ti mesh.•The fully flexible DSSC exhibited an enhanced photovoltaic performance of 8.10%.•Introduction of Er-Yb codoped TiO2 NPs improved light capturing and surface area.•The composite coated with an Nb2O5 thin layer inhibited photoelectron recombination losses.Ti-mesh supported TiO2 nanowire arrays (NWAs)/upconversion luminescence Er3+-Yb3+ codoped TiO2 nanoparticles (UC-EY-TiO2 NPs) composite structured photoanodes for fully flexible dye sensitized solar cells (DSSCs) were firstly constructed via a hydrothermal and spin coating process. UV–vis-NIR absorption spectra of the TiO2 NWAs/UC-EY-TiO2 NPs composites exhibited strong absorption around near infrared (NIR) 980 nm. The composites excited by 980 nm NIR laser could emit upconversion fluorescence at 489, 526, 549 and 658 nm, which expanded the spectral response range and sunlight capturing capability of formed flexible DSSCs. Moreover, the TiO2 NWAs/UC-EY-TiO2 NPs was coated with an Nb2O5 thin layer to further suppress electron recombination losses. The complete flexible DSSCs based on Nb2O5 coated TiO2 NWAs/2.0 mol% Er3+-1.0 mol% Yb3+ codoped TiO2 NPs photoanode and Pt/ITO-PEN counter electrode exhibited an enhanced photon to current conversion efficiency of 8.10%, a 68% improvement compared to TiO2 NWAs/undoped TiO2 NPs based DSSCs (4.82%).
Co-reporter:Guang-ju Chen;Jian-ming Gao;Mei Zhang
International Journal of Minerals, Metallurgy, and Materials 2017 Volume 24( Issue 3) pp:249-256
Publication Date(Web):2017 March
DOI:10.1007/s12613-017-1402-9
Low-nickel matte was intensively characterized, and Ni, Cu, and Co were determined to exist mainly as (Fe,Ni)9S8 and FeNi3, Cu5FeS4, and (Fe,Ni)9S8 and Fe3O4 (in isomorphic form), respectively. The efficient and selective extraction of Ni, Cu, and Co from the low-nickel matte in an (NH4)2S2O8/NH3·H2O solution system was studied. The effects of (NH4)2S2O8 and NH3·H2O concentrations, leaching time, and leaching temperature on the metal extraction efficiency were systematically investigated. During the oxidative ammonia leaching process, the metal extraction efficiencies of Ni 81.07%, Cu 93.81%, and Co 71.74% were obtained under the optimal conditions. The relatively low leaching efficiency of Ni was mainly ascribed to NiFe alloy deactivation in ammonia solution. By introducing an acid pre-leaching process into the oxidative ammonia leaching process, we achieved the high extraction efficiencies of 98.03%, 99.13%, and 85.60% for the valuable metals Ni, Cu, and Co, respectively, from the low-nickel matte.
Co-reporter:Yu-jia Sun, Yi-fei Diao, Hui-gang Wang, Guangju Chen, ... Min Guo
Ceramics International 2017 Volume 43, Issue 18(Volume 43, Issue 18) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.ceramint.2017.09.029
Spinel ferrite (Ni, Cu, Co)Fe2O4 was synthesized from the low nickel matte by using a co-precipitation-calcination method for the first time. The influences of the added amount of NiCl2·6H2O, calcination temperature and time on the structure and magnetic properties of the as-prepared ferrites were studied in detail by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman spectroscopy, and Vibrating sample magnetometer (VSM). It is indicated that pure (Ni, Cu, Co)Fe2O4 with cubic phase could be obtained under the experimental conditions (NiCl2·6H2O added amount of 3.0: 100 g mL−1, calcination temperature from 800 to 1000 °C and calcination time from 1 to 3 h). With increasing calcination temperature and time, saturation magnetization (MS) of the synthesized (Ni, Cu, Co)Fe2O4 increased and the coercivity (HC) decreased. Under the optimum conditions (i.e. NiCl2·6H2O added amount of 3.0: 100 g mL−1, 1000 °C, 3 h), the MS and HC values of the product were approximately 46.1 emu g−1 and 51.0 Oe, respectively, which were competitive to those of other nickel ferrites synthesized from pure chemical reagents. This method explores a novel pathway for efficient and comprehensive utilization of the low nickel matte.
Co-reporter:Xiaofei Wang, Hui Lu, Wenwu Liu, Min Guo, Mei Zhang
Ceramics International 2017 Volume 43, Issue 8(Volume 43, Issue 8) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.ceramint.2017.02.061
Large scale well oriented ZnO nanorod arrays (ZNRAs) were electrodeposited on flexible stainless steel mesh (SSM) substrate pre-treated by Al doped ZnO (AZO) seed layers. The effects of substrate pre-treatment conditions such as Al doping and spin coating times of the colloid on the morphology characteristics and photocatalytic properties of as-prepared ZNRAs were systematically studied. The results showed that by introducing Al into ZnO colloid solution, well aligned ZNRAs with relatively higher specific surface area (higher growth density and smaller rod diameter) could be obtained on the premodified SSM substrate. In addition, increasing spin coating times of AZO colloid solution would decrease the average diameter of ZNRAs. Under the optimum preparing conditions, the formed flexible SSM supported ZNRAs exihibited enhanced photocatalytic performance of 93.42% and remarkable photocatalytic stability under the UV-lamp for degradation of Rhodamine B.
Co-reporter:Jian-ming Gao, Mei Zhang, Fangqin Cheng, Min Guo
Hydrometallurgy 2017 Volume 173(Volume 173) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.hydromet.2017.08.004
•A simple approach to the comprehensive utilization of laterite ores is reported.•Extraction of valuable metals and synthesis of ferrite spinel materials are realized.•A reverse precipitation method is more favorable for the metal recoveries.•The overall metal recovery as spinel ferrite materials was about 85%.To comprehensively utilize the laterite resources, the present study focused on the selective recovery of valuable metals Ni, Co or Al, Cr, and concurrent synthesis of spinel ferrites from saprolite-limonite laterite leach liquors by a one-step selective precipitation method. The precipitation behaviors were investigated in detail, as were factors such as precipitant reagent, pH value, precipitation method, and initial metal ion concentration. In optimal conditions, about 93.0% Ni and 92.0% Co could be enriched in the filtrate by using ammonia (aqueous NH3) solution as precipitant reagent while the recoveries of Al and Cr were 92.0% and 90.0% by using sodium hydroxide (NaOH) solution. After the separation and selective precipitation processes, the precipitates were utilized to synthesize spinel ferrites and the effects of saprolite to limonite laterite mass ratio (MS/L) and calcination temperature on the product purity are discussed. Single phase multi-metal doped magnesium ferrites with high purity could be synthesized when the precipitates were obtained using MS/L ratio of 9:1 and 7:3 by using aqueous NH3 and NaOH solutions as precipitant reagents, and then calcined at 1000 °C for 2 h, respectively. The overall metal recoveries from laterite blends using aqueous NH3 and NaOH precipitant reagents were 89.2% and 85.4%, respectively.
Co-reporter:Nannan Jia, Xiaofei Wang, Hui-gang Wang, Mei Zhang, Min Guo
Ceramics International 2016 Volume 42(Issue 16) pp:18459-18465
Publication Date(Web):December 2016
DOI:10.1016/j.ceramint.2016.08.181
Abstract
A novel process of recovery of zinc from mixed sulfide-oxide lead and zinc ore was presented in this paper. ZnO nanorod arrays (ZNRAs) on FTO substrate pre-coated with a layer of ZnO seeds was synthesized successfully from the mixed ore via the oxidative ammoniacal leaching process and a two-step process including precipitation and hydrothermal synthesis. The characterization results from the XRD, SEM and UV–vis spectrophotometer analysis showed that the as-prepared ZNRAs was well-aligned, large-scale, perpendicular to the FTO substrate and had a reduced band gap energy of 3.03 eV. XPS analysis indicated that the grown ZNRAs were doped by a small quantity of carbon and did not contain any other impurities particularly Fe and Pb. The total zinc extraction can reach 92.4% after the oxidative ammoniacal leaching process and the precipitation process. The elimination of conventional purification process in zinc production was achieved due to the efficient and selective oxidative ammoniacal leaching process.
Co-reporter:Yang Li, Tiehong Peng, Wenkuan Man, Liangchen Ju, Feng Zheng, Mei Zhang and Min Guo
RSC Advances 2016 vol. 6(Issue 10) pp:8358-8366
Publication Date(Web):13 Jan 2016
DOI:10.1039/C5RA26881H
Ti-bearing electric arc furnace slag (Ti-bearing EAF slag) is the main solid waste generated in the direct reduction iron making process. During the extraction process of Ti from Ti-bearing EAF slag, a by-product containing abundant Si and Al was seldom utilized, thus leading to waste of valuable elements and secondary pollution. In this paper, NaA zeolite (6Na2O·6Al2O3·12SiO2) and sodalite (SOD, 4Na2O·3Al2O3·6SiO2) were synthesized successfully using the by-product as a precursor. The effects of the SiO2/Al2O3 molar ratio (n(SiO2)/n(Al2O3)), H2O/Na2O molar ratio (n(H2O)/n(Na2O)), hydrothermal temperature and time on the crystal phase and microstructure of the prepared zeolites were systematically investigated. The results indicated that NaA zeolite with good crystallinity and cubic morphology was obtained at 140 °C for 3 h with n(SiO2)/n(Al2O3) and n(H2O)/n(Na2O) fixed at 2.0:1 and 100:1, respectively. Decreasing n(H2O)/n(Na2O), raising the hydrothermal temperature and prolonging the hydrothermal time were beneficial for the formation of spherical SOD zeolite. The phase transformation between NaA and SOD zeolite was discussed and a mechanism was proposed to explain the phenomenon of these zeolites coexisting in the obtained samples. In addition, the removal performances of Cu2+ in aqueous solutions using zeolites synthesized at different temperatures were studied. The maximum removal capacity of the prepared zeolite can reach 1.346 mmol g−1 for 180 min.
Co-reporter:Wenwu Liu, Chengxun Hong, Hui-gang Wang, Mei Zhang, Min Guo
Applied Surface Science 2016 Volume 364() pp:676-685
Publication Date(Web):28 February 2016
DOI:10.1016/j.apsusc.2015.12.197
Highlights
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Nb2O5 coated hierarchical TiO2 nanowire-nanosheet arrays were prepared on Ti-mesh.
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Nb2O5 coated TiO2 HNWAs/Pt-ITO-PEN flexible DSSC was constructed.
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The fully flexible DSSC exhibited an enhanced photovoltaic performance of 4.55%.
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The reasons for the improved conversion efficiency of the DSSC were discussed.
Co-reporter:Jin-yan Li;Mei Zhang;Xue-min Yang
International Journal of Minerals, Metallurgy, and Materials 2016 Volume 23( Issue 5) pp:520-533
Publication Date(Web):2016 May
DOI:10.1007/s12613-016-1263-7
The addition of silica to steelmaking slags to decrease the binary basicity can promote phosphate enrichment in quenched slag samples. In this study, we experimentally investigated phosphate enrichment behavior in CaO–SiO2–FeO–Fe2O3–P2O5 slags with a P2O5 content of 5.00% and the binary basicity B ranging from 1.0 to 2.0, where the (%FetO)/(%CaO) mass percentage ratio was maintained at 0.955. The experimental results are explained by the defined enrichment degree \(
R_{C_2 S - C_3 P}\) of solid solution 2CaO·SiO2–3CaO·P2O5 (C2S–C3P), where \(
R_{C_2 S - C_3 P}\) is a component of the developed ion and molecule coexistence theory (IMCT)–Ni model for calculating the mass action concentrations Ni of structural units in the slags on the basis of the IMCT. The asymmetrically inverse V-shaped relation between phosphate enrichment and binary basicity B was observed to be correlated in the slags under applied two-stage cooling conditions. The maximum content of P2O5 in the C2S–C3P solid solution reached approximately 30.0% when the binary basicity B was controlled at 1.3.
Co-reporter:Hui-gang Wang;Yang Li;Jian-ming Gao
International Journal of Minerals, Metallurgy, and Materials 2016 Volume 23( Issue 2) pp:146-155
Publication Date(Web):2016 February
DOI:10.1007/s12613-016-1221-4
A novel hydrothermal process was developed to extract zinc from pure zinc ferrite (ZnFe2O4) nanopowder and zinc-containing electric arc furnace (EAF) dust using hexahydrated ferric chloride (FeCl3·6H2O) as a decomposing agent. The effects of solid FeCl3·6H2O to ZnFe2O4 ratio by mass (RF/Z), hydrothermal reaction temperature, and time on zinc extraction were systematically investigated. In the results, when the hydrothermal reaction is conducted at 150°C for 2 h with RF/Z of 15:20, the efficiency of zinc extraction from ZnFe2O4 reaches 97.2%, and the concentration of ferric ions (Fe3+) in the leaching solution is nearly zero, indicating a high selectivity for zinc. In addition, the zinc extraction efficiency from the EAF dust reaches 94.5% in the case of the hydrothermal reaction performed at 200°C for 10 h with the solid FeCl3·6H2O to EAF dust ratio by mass (RF/EAF dust) of 15:10. Zinc and iron separation is achieved by adjusting the pH value of the leaching solution according to the different precipitation pH values of metal hydroxides.
Co-reporter:Feng Zheng, Hui Lu, Min Guo, Mei Zhang and Qiang Zhen
Journal of Materials Chemistry A 2015 vol. 3(Issue 29) pp:7612-7620
Publication Date(Web):22 Jun 2015
DOI:10.1039/C5TC01125F
We reported a simple and effective hydrothermal route for fabricating WO3 nanorod array (WNR) and ZnO nanosheet array (ZNS) composite structures on FTO substrates. The morphology evolution of the WNRs grown on the FTO substrate and the ZNSs deposited on the WNRs was investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The growth mechanisms of well aligned WNRs and ZNSs were intensively studied. Moreover, the optical and photocatalytic properties of the WNR–ZNS composite structures were also examined.
Co-reporter:Feng Zheng, Wenkuan Man, Min Guo, Mei Zhang and Qiang Zhen
CrystEngComm 2015 vol. 17(Issue 29) pp:5440-5450
Publication Date(Web):08 Jun 2015
DOI:10.1039/C5CE00832H
WO3 nanostructures with various morphologies and crystallinity (such as cylinder-like WO3 nanorod arrays (WNRs-1), porous WO3 nanofibers, WO3 nanoflake arrays, sharp cone-like nanorod arrays (WNRs-2) and annealed cylinder-like WNRs-1) were prepared on FTO substrates by using a hydrothermal method without organic additives. The effects of morphology, size and crystallinity on the electrochromic properties of WO3 nanostructures were systematically investigated by scanning electron microscopy, X-ray diffraction, cyclic voltammetry and chronoamperometry. WNRs-1 exhibited excellent cyclic stability, wide optical modulation (64%), and relatively high coloration efficiency (61 cm2 C−1). Fast switching speeds of 5 s and 6 s for bleaching and coloration are achieved for WNRs-1 after annealing. Moreover, the relationship between the micro-morphologies/structures and electrochromic performance of WO3 nanostructures was also discussed.
Co-reporter:Yang Li, Yang Yang, Min Guo and Mei Zhang
RSC Advances 2015 vol. 5(Issue 18) pp:13478-13487
Publication Date(Web):15 Jan 2015
DOI:10.1039/C4RA13942A
In this paper, nanostructured titanium dioxide (TiO2) photocatalysts with different crystal structures and morphologies were successfully synthesized from titanium-bearing electric arc furnace molten slag (Ti-bearing EAF slag). The effects of different kinds of acid and acid concentrations during the acidolysis process on the crystal structures and morphologies of TiO2 were systematically studied. The TiO2 crystal phase transformation mechanism and morphology evolution in different acid systems and concentrations were discussed in detail. In addition, the photocatalytic properties of TiO2 obtained in different acid systems were investigated. It is shown that rutile and anatase type TiO2 were obtained in hydrochloric acid and sulfuric acid, respectively, while two types coexisted in nitric acid. With increasing sulfuric acid concentration, anatase would be apt to change to rutile. The growth mechanism of TiO2 from Ti-bearing EAF slag was also discussed. The TiO2 synthesized from sulfuric acid showed better photocatalytic activity than that from hydrochloric or nitric acid, and its photodegradation efficiency can reach 90.52% in 90 min for rhodamine B solutions.
Co-reporter:Zhikai Yan, Jianming Gao, Yang Li, Mei Zhang and Min Guo
RSC Advances 2015 vol. 5(Issue 112) pp:92778-92787
Publication Date(Web):12 Oct 2015
DOI:10.1039/C5RA17145H
Spinel metal-doped magnesium ferrite (MgFe2O4) was synthesized using an atmospheric hydrochloric acid leaching process and hydrothermal synthesis process from saprolite laterite. The effects of the hydrothermal preparation conditions, such as pH value of the acid leaching solution, hydrothermal temperature and time, on the formation of magnesium ferrite were systematically investigated. It was shown that pure magnesium ferrite could be obtained when the pH value of the leaching solution was controlled at 12.0 and the hydrothermal reaction was conducted at 160 °C for 6 h. More importantly, the structural evolution of the as-prepared magnesium ferrite was investigated in detail using X-ray diffraction (XRD), X-ray fluorescence (XRF), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The results indicated that the metal-doped magnesium ferrite displayed soft ferrimagnetic behavior and the magnesium ions migrated from the tetrahedral site to the octahedral site as the calcination temperature increased. The formed magnesium ferrite was indeed mixed with traces of other magnesium-containing compounds.
Co-reporter:Wenkuan Man, Hui Lu, Liangchen Ju, Feng Zheng, Mei Zhang and Min Guo
RSC Advances 2015 vol. 5(Issue 128) pp:106182-106190
Publication Date(Web):10 Dec 2015
DOI:10.1039/C5RA20970F
WO3 nanorod arrays (WNRAs) were successfully synthesized on an FTO substrate pre-coated with a layer of TiO2 seeds. The morphology and micro-structure were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The effect of substrate pre-treatment on electrochromic (EC) properties of as-prepared WNRAs was investigated in detail. Compared with those synthesized on WO3 seed layer, the WNRAs grown on TiO2 seed layer showed a large optical modulation (77.5%, at 660 nm) and high coloration efficiency (142.7 cm2 C−1) under the optimal preparation conditions. In addition, the influence of annealing temperature of the TiO2 seed layer on the EC performance was also discussed. More importantly, the WNRAs grown on the TiO2 seed layer presented good stability and strong adhesion to the FTO substrate during the test process.
Co-reporter:Wenwu Liu, Hui Lu, Mei Zhang, Min Guo
Applied Surface Science 2015 Volume 347() pp:214-223
Publication Date(Web):30 August 2015
DOI:10.1016/j.apsusc.2015.04.090
Highlights
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Flexible titanium mesh was first used for hydrothermal preparation of TiO2 NWAs.
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The formation mechanism of the TiO2 nanostructures was discussed.
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The density, average diameter, and morphology of TiO2 NWAs can be controlled.
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The effects of the sensitization temperature and time on the properties were studied.
Co-reporter:Jian-ming Gao, Zhi-kai Yan, Jing Liu, Mei Zhang, Min Guo
Materials Letters 2015 Volume 141() pp:122-124
Publication Date(Web):15 February 2015
DOI:10.1016/j.matlet.2014.11.062
•Zn substituted Ni–Co–Mn–Mg ferrites were synthesized from laterite leaching solution.•Effect of Zn substitution on the structure and magnetic properties was investigated.•The as-prepared sample with Zn doping amount of 0.4 showed best magnetic properties.•This paper explored a simple pathway to produce ferrites with excellent properties.A series of Zn substituted Ni–Co–Mn–Mg ferrites were synthesized from the laterite leaching solutions with different contents of ZnCl2 by using a coprecipitation method. The effects of Zn substitution on the structure and magnetic properties of as-prepared samples were investigated. XRD results revealed that all the samples were single-phase of cubic spinel, and the lattice constant and average grain size increased simultaneously with increase in Zn doping amount. Magnetic property tests indicated that when the Zn doping amount was increased from 0 to 0.80, the Ms values initially increased from 29.6 to 55.6 emu g−1 and then decreased to 4 emu g−1, while the Hc values kept gradually decreasing from 55 to 4 Oe. Specifically, when the Zn doping amount was controlled at 0.40, the Ms and Hc values of the as-prepared sample were 55.6 emu g−1 and 32 Oe, respectively. And the results can be explained by Neel׳s two sublattice and Yafet–Kittle configuration models.
Co-reporter:Hui Lu, Xiangyang Zhai, Wenwu Liu, Mei Zhang, Min Guo
Thin Solid Films 2015 Volume 586() pp:46-53
Publication Date(Web):1 July 2015
DOI:10.1016/j.tsf.2015.04.056
•Hierarchical ZnO nanorod arrays (ZNRAs) were prepared by electrodeposition method.•Flexible stainless steel mesh (SSM) supported with hierarchical ZNRAs was first used for DSSCs.•The effect of ZnO morphology on the photovoltaic performance of flexible DSSCs was investigated.•The DSSC based on 3-Hierarchical ZNRAs/ZNPs showed a relatively efficiency of 1.11%.Hierarchical ZnO nanorod arrays (ZNRAs) were synthesized on flexible stainless steel mesh (SSM) in large scale by a two-step facile electrodeposition method. The structure and morphology of the as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The growth mechanism of the ZnO hierarchical nanostructures was also discussed. Moreover, the effect of ZnO morphology on the photovoltaic performance of the flexible DSSCs based on SSM supported ZnO nanostructures was investigated in detail. It is shown that the flexible DSSCs exhibited a relatively higher power conversion efficiency of 1.11% compared with that based on primary ZNRAs.
Co-reporter:Zai-Qing Que;Yang Li;Hai-Yang Yu;Feng Zheng;Mei Zhang
Rare Metals 2015 Volume 34( Issue 4) pp:267-275
Publication Date(Web):2015 April
DOI:10.1007/s12598-013-0129-7
Nanostructured TiO2 with different morphologies and crystal phases was successfully synthesized from titanium-containing electric furnace molten slag by using a hydrothermal method followed by reflux process in acid solution. The effects of acid concentration, reflux time, and acid type on the formation of TiO2 were systematically investigated by scanning electron microscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and X-ray fluorescence (XRF). It is indicated that TiO2 nanorod with rutile phase is achieved in nitric or hydrochloric acid, while anatase TiO2 nanodisk is formed in sulfuric acid. With the increase of the concentration of hydrochloric acid from 0.3 to 1.5 mol·L−1, the dispersibility and crystallinity of the final product can be improved. With prolonging the reflux time from 6 to 14 h, the rutile TiO2 nanorod with uniform crystal size and high crystallinity is obtained. The growth mechanism of TiO2 nanorod and nanodisk prepared under different conditions was also discussed.
Co-reporter:Hui Lu, Mei Zhang, Min Guo
Applied Surface Science 2014 Volume 317() pp:672-681
Publication Date(Web):30 October 2014
DOI:10.1016/j.apsusc.2014.08.153
Highlights
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ZnO nanorod arrays (ZNRAs) were prepared by electrodeposition method.
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Flexible stainless steel mesh (SSM) was first used for electrodeposition of ZNRAs.
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The morphology, average diameter and density of ZNRAs can be controlled to some extent.
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The ZNRAs prepared with more electrodeposition times showed enhanced photocatalytic performance.
Co-reporter:Jin-yan Li;Mei Zhang;Xue-Min Yang
Metallurgical and Materials Transactions B 2014 Volume 45( Issue 5) pp:1666-1682
Publication Date(Web):2014 October
DOI:10.1007/s11663-014-0085-0
The phosphate-enrichment behavior has experimentally been investigated in CaO-SiO2-FeO-Fe2O3-P2O5 steelmaking slags. The reaction ability of structural units in the slags has been represented the mass action concentration \( N_{i} \) from the developed ion and molecule coexistence theory (IMCT)-\( N_{i} \) model based on the IMCT. The defined enrichment possibility \( N_{{{\text{c}}i{\text{ {-}c}}j}} \) and enrichment degree \( R_{{{\text{c}}i{\text{{-}c}}j}} \) of solid solutions containing P2O5 from the developed IMCT-\( N_{i} \) model have been verified from the experimental results. The effects of binary basicity, the mass percentage ratio \( {{ ( {\text{pct Fe}}_{t} {\text{O)}}} \mathord{\left/ {\vphantom {{ ( {\text{pct Fe}}_{t} {\text{O)}}} { ( {\text{pct CaO)}}}}} \right. \kern-0pt} { ( {\text{pct CaO)}}}} \), and mass percentage of P2O5 in the initial slags on phosphate-enrichment behavior in the slags has also been discussed. The results show that the P2O5 component can easily be bonded by CaO to form tricalcium phosphate 3 CaO·P2O5, and the formed 3CaO·P2O5 can react with the produced dicalcium silicate 2CaO·SiO2 to generate solid-solution 2CaO·SiO2-3CaO·P2O5 under fixed cooling conditions. The maximum value of the defined enrichment degree \( R_{{{\text{C}}_{ 2} {\text{S{-}}} {\text{C}}_{ 3} {\text{P}}}} \) of solid-solution 2CaO·SiO2-3CaO·P2O5 is obtained as 0.844 under conditions of binary basicity as 2.5 and the mass percentage ratio \( {{ ( {\text{pct Fe}}_{t} {\text{O)}}} \mathord{\left/ {\vphantom {{ ( {\text{pct Fe}}_{t} {\text{O)}}} { ( {\text{pct CaO)}}}}} \right. \kern-0pt} { ( {\text{pct CaO)}}}} \) as 0.955 at fixed cooling conditions.
Co-reporter:Feng Zheng, Hui Lu, Min Guo and Mei Zhang
CrystEngComm 2013 vol. 15(Issue 29) pp:5828-5837
Publication Date(Web):20 May 2013
DOI:10.1039/C3CE40494C
Hexagonal WO3 nanostructures with controlled sizes and alignment ordering have been successfully realized on fluorine doped tin oxide (FTO) substrates with different pre-treatment methods by a hydrothermal approach. The effects of the pre-treatment conditions, such as pre-coating a layer of WO3 nanoparticles, the annealing temperature and time and the colloid concentration, on the orientation and morphology of the WO3 nanorods were systematically investigated by scanning electron microscopy and X-ray diffraction. The WO3 nanorod arrays (WNRs) vertical to the FTO substrate and spindle-like nanorod bundles parallel to the FTO substrate can be selectively prepared depending on the crystallinity and the density of the WO3 seeds pre-coated on the FTO substrates. Moreover, the influence of the as-prepared WO3 morphology on its electrochromic (EC) property was also discussed.
Co-reporter:Feng Zheng, Min Guo and Mei Zhang
CrystEngComm 2013 vol. 15(Issue 2) pp:277-284
Publication Date(Web):24 Oct 2012
DOI:10.1039/C2CE25996F
The orientation controlled synthesis of h-WO3 nanostructures on ITO substrates has been successfully realized in large scale via a simple hydrothermal method. The influences of pH value and growth time on the orientation and morphology of WO3 nanostructures were investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The nanorod bundles parallel to ITO substrate and nanorod arrays vertical to ITO substrate can be selectively prepared by adjusting the final pH value just to 2.0 and 2.4, respectively. The morphology evolution and the growth mechanism of well aligned WO3 nanorod arrays were intensively studied. Moreover, the optical properties of the WO3 with different oriented alignment were also examined.
Co-reporter:Yang Li;Yi Yue;Zai-qing Que;Mei Zhang
International Journal of Minerals, Metallurgy, and Materials 2013 Volume 20( Issue 10) pp:1012-1020
Publication Date(Web):2013 October
DOI:10.1007/s12613-013-0828-y
Nanostructured Fe-doped titanium dioxide was synthesized from titanium containing electric furnace molten slag (TCEFMS) by using an alkali fusion, followed by a hydrolyzation-acidolysis-calcination route. The effects of alkali/slag mass ratio, calcinating temperature, calcinating time, and water/slag mass ratio on the extraction efficiency and purity of products were systematically studied in this paper. It is indicated that the best extraction efficiency of nanostructured Fedoped titanium dioxide is 99.35%, when the molten slag is calcinated at 700°C for 1 h with the mass ratio of alkali/molten slag of 1.5:1. The influence of alkali/slag mass ratio on the photocatalytic activity of final products was evaluated by the photodegradation of methyl blue under visible light irradiation. A maximum photodegradation efficiency of 88.12% over 30 min was achieved under the optimum conditions.
Co-reporter:Yan Zhao;Jian-ming Gao;Yi Yue;Ben Peng
International Journal of Minerals, Metallurgy, and Materials 2013 Volume 20( Issue 7) pp:612-619
Publication Date(Web):2013 July
DOI:10.1007/s12613-013-0774-8
Extraction and separation of nickel and cobalt from saprolite laterite ore were studied by using a method of microwave-assisted hydrothermal leaching and chemical deposition. The effects of leaching temperature and time on the extraction efficiencies of Ni2+ and Co2+ were investigated in detail under microwave conditions. It is shown that the extraction efficiencies of Ni2+ and Co2+ from the ore pre-roasted at 300°C for 5 h were 89.19% and 61.89% when the leaching temperature and time were about 70°C and 60 min, respectively. For the separation process of Ni and Co, the separation of main chemical components was performed by adjusting the pH values of sulfuric leaching solutions using a NaOH solution based on the different pH values of precipitation for metal hydroxides. The final separation efficiencies of Ni and Co were 77.29% and 65.87%, respectively. Furthermore, the separation efficiencies of Fe of 95.36% and Mg of 92.2% were also achieved at the same time.
Co-reporter:Xiao Guo;Feng Zheng;Mei Zhang;Kuo-Chih Chou
Rare Metals 2013 Volume 32( Issue 2) pp:179-185
Publication Date(Web):2013/04/01
DOI:10.1007/s12598-013-0042-0
Nickel nanoparticles (<10 nm) were successfully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/polyvinylpyrrolidone (PVP) system. The effects of three factors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP (surfactant), were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy (TEM) reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 2–5 nm under selected conditions. High-resolution TEM and energy-dispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UV–visible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.
Co-reporter:Feng Zheng, Mei Zhang, Min Guo
Thin Solid Films 2013 Volume 534() pp:45-53
Publication Date(Web):1 May 2013
DOI:10.1016/j.tsf.2013.01.102
WO3 nanorod arrays (WNRs) were synthesized on indium tin oxide conducting substrates by hydrothermal method. The effects of preparing conditions such as the precursor solutions concentration (H+ and Na2WO4), the additive NaCl, growth temperature and reaction time on the morphologies of WNRs have been systematically investigated by scanning electron microscopy, X-ray diffraction, Raman spectrum and ultraviolet visible absorption spectrum. It is shown that the pH value of the precursor solutions plays an important role in determining the morphology of as-prepared WNRs, which leads to different band gap energies. The orientation, density, and crystallinity of WNRs can be controlled by changing the amount of additive NaCl, Na2WO4 concentration and reaction temperature, respectively. Moreover, the growth mechanism of the WNRs was also discussed.Highlights► WO3 nanorod arrays were prepared on indium tin oxide substrate by hydrothermal method. ► The effects of preparing conditions on the growth of WO3 nanorod arrays were studied. ► The band gap energy of WO3 nanorod arrays can be controlled by adjusting pH value.
Co-reporter:Yali Wang, Min Guo, Mei Zhang, Xidong Wang
Thin Solid Films 2010 Volume 518(Issue 18) pp:5098-5103
Publication Date(Web):1 July 2010
DOI:10.1016/j.tsf.2010.03.003
SnO2 nanograss array films (SNAFs) were synthesized on indium tin oxide glass substrates by hydrothermal method. The effects of preparing conditions such as precursor concentration, reaction temperature and growth time on the formation of the SNAFs have been investigated in detail by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and photoluminescence spectrum. It is shown that the precursor concentration plays an important role in determining the morphology of the prepared SnO2. The average diameter, length and growth rate of the SNAFs can be controlled to some extent by varying growth time. The reaction temperature has also influence on the growth rate of SNAFs. Moreover, the growth mechanism of the SNAFs was also discussed. Room-temperature photoluminescence spectra were further carried out to investigate their optical properties.
Co-reporter:Yuxiang Li;Mei Zhang;Xidong Wang
Rare Metals 2010 Volume 29( Issue 3) pp:286-291
Publication Date(Web):2010 June
DOI:10.1007/s12598-010-0050-2
Well-aligned TiO2 nanorod arrays (TNAs) were prepared on pretreated quartz substrates via hydrothermal method. The effect of the different preparation conditions on the growth morphologies of TNAs was systematically investigated by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The photocatalytic properties were tested by photodegradation of a methyl blue solution. It is demonstrated that the hydrothermal reaction conditions, such as precursor concentration, hydrothermal reaction temperature, and hydrothermal reaction times, can greatly affect the growth of TNAs. Controlling the preparation process, TNAs with 2 μm in length and 140–170 nm in diameter and well-aligned orientation have been successfully prepared. The photocatalytic experiment results indicate that TNAs have much better photocatalytic activity than TiO2 nanoparticles.
Co-reporter:Yang Li, Lulu Liu, Min Guo, Mei Zhang
Journal of Environmental Sciences (September 2016) Volume 47() pp:14-22
Publication Date(Web):1 September 2016
DOI:10.1016/j.jes.2015.11.032
TiO2 visible light catalysts with different crystalline phases and morphologies were synthesized from titanium-bearing electric arc furnace molten slag (Ti-bearing EAF slag) by using a simple acidolysis process. The effects of the pH of the HCl solution, liquid to solid ratio (RL/S, HCl solution to the residue ratio, mL/g) and acidolysis time on the micro-morphology and crystalline phase of as-prepared TiO2 photocatalysts were systematically investigated. The results indicated that with decreasing pH in the HCl solution and increasing RL/S, the crystalline phase and micro-morphology of the obtained TiO2 nanostructures tended to transform from anatase type TiO2 with spherical nanoparticle structures to rutile type TiO2 with needle-like nanorod structures. The acidolysis time had little influence on the crystalline phase but great impact on the size of the obtained TiO2. The growth mechanism of TiO2 from Ti-bearing EAF slag during the acidolysis process was also discussed. In addition, the influence of RL/S on the photocatalytic properties of the synthesized nanostructured TiO2 was studied. The results showed that the photodegradation efficiency for Rhodamine B solution could reach 91.00% in 120 min when the RL/S was controlled at 50:1.Download high-res image (332KB)Download full-size image
Co-reporter:Zhipeng Zhao, Min Guo, Mei Zhang
Journal of Hazardous Materials (9 April 2015) Volume 286() pp:402-409
Publication Date(Web):9 April 2015
DOI:10.1016/j.jhazmat.2014.12.063
•Mo and V were extracted from spent diesel exhaust catalyst by ammonia leaching method.•Effects of leaching parameters on the extraction of Mo and V were studied in detail.•The extraction efficiencies of Mo and V could reach 94.96% and 39.73%.•The leaching solution and the residue can be reused for preparing new catalyst.Molybdenum (Mo) and vanadium (V) were effectively extracted from the spent diesel exhaust catalyst (V2O5–MoO3/TiO2) by using an ammonia leaching method. Meanwhile, the structure of the spent catalyst carrier (TiO2) was not destroyed and might be reused. The effects of ammonia (NH3·H2O) concentration, leaching temperature and time, concentration of hydrogen peroxide (H2O2) and liquid to solid ratio on the extraction of Mo and V were systematically investigated. It is shown that the extraction efficiency of Mo increased from 68.68% to 96.45% while the extraction efficiency of V remained stable at 27% with increasing ammonia concentration from 2.95 to 7.38 mol/L, leaching temperature from 298.15 to 473.15 K, and reaction time from 1 to 8 h. With the concentration of H2O2 solution increasing from 1.0 to 2.5 mol/L, the extraction efficiency of V increased from 26.87% to 39.73%. Under the optimum conditions (the ammonia concentration of 4.5 mol/L, leaching temperature of 413.15 K, reaction time of 2 h, the H2O2 solution concentration of 1.0 mol/L and the liquid to solid ratio of 20/1 mL/g), the extraction efficiencies of Mo and V reached 95.13% and 46.25%. Moreover, the catalyst carrier TiO2 with anatase crystal phase was also obtained.
Co-reporter:Hui-gang Wang, Wenwu Liu, Nannan Jia, Mei Zhang, Min Guo
Ceramics International (1 February 2017) Volume 43(Issue 2) pp:
Publication Date(Web):1 February 2017
DOI:10.1016/j.ceramint.2016.10.164
Metal-doped Ni-Zn ferrite with a spinel structure was directly synthesized from treated zinc-containing electric arc furnace dust (Zn-containing EAFD) by solid state reaction method, realizing the transformation of solid waste to high value-added material. First, NiCl2·6H2O was added to the treated Zn-containing EAFD before calcination. Then, the effects of the mass ratio of treated Zn-containing EAFD to NiCl2·6H2O (RTZE/N, g g−1) and the calcination temperature on the synthesis and magnetic properties of as-synthesized samples were systematically investigated by X-ray diffraction, Raman spectroscopy and physical property measurement. It was found that RTZE/N and calcination temperature significantly influenced the synthesis of single-phase spinel ferrite and their magnetic properties. Pure metal-doped Ni-Zn ferrite, exhibiting good magnetic properties of higher saturation magnetization (Ms, 60.5 emu g−1) and lower coercivity (Hc, 49.8 Oe), was obtained when the calcination temperature was controlled at 1100 °C for 2 h with a RTZE/N of 1:0.9.
Co-reporter:Wenwu Liu, Hui-gang Wang, Xiaofei Wang, Mei Zhang and Min Guo
Journal of Materials Chemistry A 2016 - vol. 4(Issue 47) pp:NaN11128-11128
Publication Date(Web):2016/10/31
DOI:10.1039/C6TC03680E
TiO2 nanowire arrays (NWAs)/Nb-doped TiO2 nanoparticles (NPs) composite structures were first synthesized on flexible titanium (Ti) meshes as a photoanode of dye sensitized solar cells (DSSCs) using a two-step hydrothermal and spin-coating approach. Three key factors, including the sunlight harvesting efficiency (ηlh), electron injection efficiency (ηinj) and electron collection efficiency (ηec), which determine the conversion efficiency of flexible DSSC, are discussed in detail. The introduction of appropriate amounts of Nb-doping into the TiO2 lattice was found to effectively improve the photovoltaic properties of flexible DSSCs. Mott–Schottky analysis showed that flat-band potential (Vfb) of the Nb-doped TiO2 had a positive shift, which promoted photogenerated electron injection from dye molecules to the TiO2 conduction band more energetically. The electrochemical impedance spectroscopy (EIS) measurement of the DSSCs under illumination demonstrated that photoelectrons could transfer faster in the Nb-doped TiO2 composite. The EIS analysis in the dark indicated that slight Nb-doping reduced the shallow energy level trapping amounts to decrease electron recombination losses. The fully flexible DSSCs assembled by TiO2 NWAs/2.4 mol% Nb-doped TiO2 NPs photoanode and PEN/ITO-Pt photocathode displayed an increase in the Jsc value from 9.98 to 13.60 mA cm−2 and Voc from 0.74 to 0.78 V, thereby exhibiting a good 7.20% photovoltaic efficiency, which was superior to that of the undoped TiO2 composite structures (4.96%).
Co-reporter:Feng Zheng, Hui Lu, Min Guo, Mei Zhang and Qiang Zhen
Journal of Materials Chemistry A 2015 - vol. 3(Issue 29) pp:NaN7620-7620
Publication Date(Web):2015/06/22
DOI:10.1039/C5TC01125F
We reported a simple and effective hydrothermal route for fabricating WO3 nanorod array (WNR) and ZnO nanosheet array (ZNS) composite structures on FTO substrates. The morphology evolution of the WNRs grown on the FTO substrate and the ZNSs deposited on the WNRs was investigated by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The growth mechanisms of well aligned WNRs and ZNSs were intensively studied. Moreover, the optical and photocatalytic properties of the WNR–ZNS composite structures were also examined.
