ACS Applied Materials & Interfaces
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2015
·
IF 6.723
Zichao Lian,Pengpeng Xu,Wenchao Wang,Dieqing Zhang,Shuning Xiao,Xin Li,Guisheng Li
Fullerene (C60) enhanced mesoporous CdS/TiO2 architectures were fabricated by an evaporation induced self-assembly route together with an ion-exchanged method. C60 clusters were incorporated into the pore wall of mesoporous CdS/TiO2 with the formation of C60 enhanced CdS/TiO2 hybrid architectures, for achieving the enhanced photostability and photocatalytic activity in H2 evolution under visible-light irradiation. Such greatly enhanced photocatalytic performance and photostability could be due to the strong combination and heterojunctions between C60 and CdS/TiO2. The as-formed C60 cluster protection layers in the CdS/TiO2 framework not only improve the light absorption capability, but also greatly accelerated the photogenerated electron transfer to C60 clusters for H2 evolution.
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RSC Advances
·
2015
·Vol. 5
·期 20
·15110-15117
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IF 3.84
Chunyan Zhang,Jiasheng Lai,Juncheng Hu
A series of Mn-doped CdS hollow sphere photocatalysts has been directly synthesized by a simple and facile hydrothermal route for the first time. It was demonstrated that GSH acts as the S source and a gas bubble-template in this process. The products were characterized by XRD, SEM, TEM, HRTEM, XPS, and UV-vis spectroscopy. The as-prepared CdS and Mn-doped CdS hollow spheres all showed much higher activity than P25 under visible light (λ > 420 nm) irradiation. Among them, the 2.0 mol% Mn-doped CdS sample exhibited the highest photoactivity for the removal of organic pollutant RhB, and about 99.2% MO was decomposed after 50 min of visible light irradiation. Moreover, this catalyst also showed good stability, and after four cycles, the degradation efficiency still remained at 85%. The excellent photoactivity of the as-prepared Mn-doped CdS hollow spheres could be attributed to the synergistic effects of its appropriate band-gap structure and the special porous spherical morphology. The unique hollow sphere structure may favor the harvesting of excited light due to its special multiple scattering effect within the interior space, and the doping of Mn2+ may facilitate the generation of photoinduced electrons and hole pairs, and inhibit their recombination rate by acting as temporary trapping sites. This material may have great application potentials in environmental remediation and energy harvesting.
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Journal of Physical Chemistry C
·
2015
·
IF 4.772
Junwei Yang,Jin Wang,Ke Zhao,Takuya Izuishi,Yan Li,Qing Shen,Xinhua Zhong
Surface trap defects are the limited factor for quantum dots (QDs) application in solar cells. The trapping states can be efficiently suppressed by coating a shell of wider band gap material around the core QDs. We choose CdSe0.65Te0.35 (simplified as CdSeTe) as a model core material, and CdS shell was then overcoated around the CdSeTe core QD to decrease surface defect density and to increase the stability of the core QDs. By optimizing the thickness of the CdS shell, the power conversion efficiency (PCE) of the CdSeTe/CdS quantum dots sensitized solar cells (QDSCs) is enhanced by 13% in comparison with that of plain CdSeTe QDSCs. Transient absorption (TA), incident-photo-to-carrier conversion efficiency (IPCE), open-circuit voltage decay (OVCD), and electrochemical impedance spectroscopy (EIS) measurements confirmed the suppressed charge recombination process in internal QDs and QD/TiO2/electrolyte interfaces with the overcoating of CdS shell around CdSeTe core QDs. With the further overcoating of a-TiO2 and SiO2 barrier layers around the QD-sensitized photoanode, the PCE of champion CdSeTe QDSCs achieved 9.48% (Jsc = 20.82 mA/cm2, Voc = 0.713 V, FF = 0.639) with average PCE 9.39 ± 0.09% under AM 1.5 G one full sun illumination.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
·
IF 9.446
Qianxin Zhang,Ping Chen,Meihui Zhuo,Fengliang Wang,Yuehan Su,Tiansheng Chen,Kun Yao,Zongwei Cai,Wenying Lv,Guoguang Liu
In this study, novel carbon dots/BiPO 4 (CDBP) photocatalytic complexes were successfully synthesized via a facile hydrothermal-calcination synthesis strategy. The physicochemical properties of the synthesized samples were studied by X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (DRS), Fourier infrared spectrometer (FT-IR), Raman spectrometer, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), photoluminescence26spectra (PL), electrochemical workstation, etc. The activities of the CDBP were evaluated through the photocatalytic degradation of Indometacin(IDM) in an aqueous solution under simulated sunlight irradiation. With increasing concentrations of carbon dots (CDs), the photocatalytic activity of the CDBP initially increased, and then decreased. A CDs content of 3.0 wt% shows 12 times higher photocatalytic activity than that of pristine BiPO 4 . Reactive oxidative species, particularly O 2 − and h + , were the two critical reactive oxidative species to mediator immediate the photocatalytic degradation of IDM. A notable sign of 5, 5-dimethyl-1-pyrrolidone-N-oxyl(DMPOX) was observed through electron spin resonance spectroscopy(EPR) with CDBP as the photocatalyst, which indicated higher oxidability than pristine BiPO 4 under simulated sunlight irradiation. This enhanced photocatalytic activity might due to high-efficiency charge separation, unique up-converted PL properties, as well as the bandgap narrowing of the CDs. Moreover, the byproducts of IDM were detected by HPLC–MS/MS and GC–MS, and the probable pathways were deduced. The acute toxicity at three trophic levels initially increased slowly and then decreased rapidly as the IDM dechlorination and total organic carbon(TOC) decreased during photocatalytic degradation.
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CHEMOSPHERE
·
2017
·
IF 4.208
Xu Chen,Yong Sik Ok,Dinesh Mohan,Charles U. Pittman,Xiaomin Dou
The increasingly wide use of semiconductor nanocrystals inevitably leads to their release into aquatic environment. The aggregation behaviors of 3-mercaptopropionic acid-capped CdSe/CdS core-shell quantum dots (MPA-QDs) under various water chemistry conditions were examined and their removal using Fe 3+ and Al 3+ coagulants was evaluated. Cationic species rather than concentrations affected the stability of MPA-QDs. Adding 2 mM Ca 2+ led to a much larger ζ-potential decrease and particle size increase than adding 150 mM K + at each tested solution pH. This indicated that complexation and depletion of surface-bound carboxyl groups by divalent Ca 2+ has a more pronounced effect than compression of the electrical double layer by high concentrations of monovalent K + . The presence of humic acid increased the stability of MPA-QDs, which might increase negative surface charging via overcoating or bind to the surface of MPA-QDs. The nanoparticles exhibited similar aggregation kinetics patterns in tap water and seawater, but varying patterns in the lake water because of the co-existence of 2.3 mM total of Ca 2+ and Mg 2+ . MPA-QDs (5 mg L −1 ) were readily coagulated by 2.4 mM Al 3+ or 1.2 mM Fe 3+ in tap water. Al 3+ and Fe 3+ can bind with carboxyl groups of the surface capping ligands, neutralize the negative charges on the surface of MPA-QDs and decrease the electrostatic repulsion forces to induce MPA-QDs aggregation. In addition, MPA-QDs could be bound with and wrapped into the flocs of hydrolysis products of coagulants. The results reported here could help broaden our understanding of the impacts and remediation of water-dispersed core-shell QD nanoparticles.
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JOURNAL OF NANOPARTICLE RESEARCH
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2016
·Vol. 18
·期 12
·1-16
·
IF 2.101
Li Zhenzhen,Zhang Qiyi,Huang Huaying,Ren Changjing,Pan Yujin,Wang Qing,Zhao Qiang
In the experiments, high-quality, water-soluble and near-infrared (NIR)-emitting CdSeTe and CdSeTe/CdS quantum dots (QDs) were successfully prepared. The average size of CdSeTe⁄CdS QDs was 7.68 nm and CdSeTe QDs was 4.33 nm. Arginine-glycine-aspartic-serine acid (RGDS) peptides were linked to CdSeTe/CdS QDs by N-(3-(dimethylamino)propyl)-N′-ehtylcarbodiimide hydrochloride (EDC) and N′-hydroxysuccinimide (NHS). The prepared RGDS-tagged NIR CdSeTe/CdS QDs (denoted as RGDS-CdSeTe/CdS) had an average diameter of 24.83 nm and were used for cancer cell immunofluorescence imaging. The characteristics of RGDS-conjugated CdSeTe/CdS such as morphology, structure, spectra, stability, cytotoxicity, and near-infrared microscopic imaging were investigated in detail. HepG2 cells were incubated with the novel fluorescent probe (RGDS-CdSeTe/CdS), which realized immunofluorescence targeting and imaging. The results reported here open up new perspectives for integrin-targeted near-infrared imaging and may aid in tumor detection including imaging-guided surgery.
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Journal of the American Chemical Society
·
2016
·
IF 13.038
Chaodan Pu,Xiaogang Peng
Electronic traps at the inorganic–organic interface of colloidal quantum dots (QDs) are detrimental to their luminescent properties. Several types of interface traps were identified for single-crystalline CdSe/CdS core/shell QDs, which were all found to be extrinsic to either the core/shell structure or their optical performance. The electron traps—presumably excess or unpassivated Cd surface sites—are shallow ones and could be readily isolated from the electron wave function of the excitons with more than ∼2 monolayers of CdS shell. There were two identifiable deep hole traps within the bandgap of the QDs, i.e., the surface adsorbed H2S and unpassivated surface S sites. The surface adsorbed H2S could be removed by either degassing processes or photochemical decomposition of H2S without damaging the QDs. The unpassivated surface S sites could be removed by surface treatment with cadmium carboxylates. Understanding of the surface traps enabled establishment of new phosphine-free synthetic schemes for either single-precursor or successive-ion-layer-adsorption-and-reaction approach, which yielded CdSe/CdS core/shell QDs with near-unity photoluminescence quantum yield and monoexponential photoluminescence decay dynamics with 2–10 monolayers of CdS shell.
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Journal of the American Chemical Society
·
2016
·
IF 13.038
Jianhai Zhou,Chaodan Pu,Tianyu Jiao,Xiaoqi Hou,Xiaogang Peng
CdSe magic-size clusters with close-shell surface and fixed molecular formula are well-known in the size range between ∼1 and 3 nm. By applying high concentration of cadmium alkanoates as ligands, a conventional synthetic system for CdSe nanocrystals was tuned to discriminate completion from initiation of atomic flat facets. This resulted in ∼4–13 nm CdSe nanocrystals with hexahedral shape terminated with low-index facets, namely three (100), one (110), and two (111) facets. These low-symmetry (Cs group with single mirror plane) yet monodisperse hexahedra were found to be persistent not only in a broad size range but also under typical synthetic temperatures for growth of both CdSe and CdS. Atomic motion on the surface of the nanocrystals under enhanced ligand dynamics initiated intraparticle ripening without activating interparticle ripening, which converted the hexahedral nanocrystals to monodisperse spherical ones. This new synthetic strategy rendered optimal color purity of photoluminescence (PL) of the CdSe and CdSe/CdS core/shell nanocrystals, with the ensemble PL peak width comparable with that of a corresponding single dot.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2016
·
IF 3.782
Hui Feng,Niu Tang,Songbai Zhang,Bo Liu,Qingyun Cai
A novel (CdS-Mn/MoS 2 /CdTe)-sensitized TiO 2 nanotube arrays (NTAs) photoelectrode has been prepared by electrodeposite, successive ionic layer adsorption and reaction (SILAR) coupled with hydrothermal method . When a ZnS layer was added on the top of CdS-Mn/MoS 2 /CdTe/TiO 2 , a notable red-shift and high absorption was observed in the visible light region. The photocurrent density (mA/cm 2 ) systematically increases from TiO 2 NTAs (0.43), CdTe/TiO 2 (1.09), MoS 2 /CdTe/TiO 2 (1.80), CdS-Mn/MoS 2 /CdTe/TiO 2 (2.40), to ZnS/CdS-Mn/MoS 2 /CdTe/TiO 2 (3.41) under visible light irradiation, due to the type-II semiconductor heterostructures comprising multiple components with a staggered band offset. Such a heterostructure possesses an enhanced photocatalytic performance towards degradation of organic contaminant, e.g. P-Nitrophenol (PNP) and Rhodamine B (RhB) .
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RSC Advances
·
2017
·Vol. 7
·期 71
·44626-44631
·
IF 3.108
Xianglin Zhu,Peng Wang,Qianqian Zhang,Zeyan Wang,Yuanyuan Liu,Xiaoyan Qin,Xiaoyang Zhang,Ying Dai,Baibiao Huang
A CdS–MoS2 photoelectrode with a double-layer core–shell structure was prepared using a simple electrodeposition–in situ sulfurization method on a Mo substrate. The photocatalytic activity of as-prepared electrodes was evaluated using a photoelectrochemical H2-generation experiment. The photocurrent and photon–electron conversion efficiency of the CdS–MoS2 photoelectrode were nearly double those of a CdS photoanode prepared on FTO glass. The high activity of the CdS–MoS2 photoelectrode was due to the higher separation efficiency of carriers caused by the formed CdS–MoS2 Janus heterojunction structure, which made directional transmission and electron–hole separation possible. Our experiments show that, in addition to being a good co-catalyst in powder material for photocatalytic hydrogen production, MoS2 can also be used as an electron acceptor layer to enhance electron–hole separation.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
·
IF 9.446
Bo Wang,Wenhui Feng,Lulu Zhang,Yan Zhang,Xueyan Huang,Zhibin Fang,Ping Liu
A novel Bi/CdS nanocomposite is obtained via an in-situ chemical reduction method under mild conditions. The incorporation of Bi nanostructure can significantly enhance the photocatalytic performance for methyl orange (MO) and salicylic acid (SA) degradation compared with pristine CdS under visible light irradiation. The dramatically improved photoactivity can be attributed to the enhanced light absorption and optimized charge separation. In addition, the photocatalysis mechanism upon Bi/CdS for MO degradation is also investigated. This study is hoped to provide a new inspiration for the construction of high-efficiency semimetal/semiconductor photocatalysts, especially for non-noble metal/M x S y nanocomposites.
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NANOTECHNOLOGY
·
2016
·Vol. 27
·期 35
·355402
·
IF 3.573
Chunyan Zhang,Yongfeng Lu,Qingqing Jiang,Juncheng Hu
CdS hollow spheres (CdS HS) coupled with graphitic carbon nitride (g-C3N4) photocatalysts are synthesized and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflection spectroscopy (DRS), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence spectroscopy (PL). The effect of CdS content on CdS HS/g-C3N4 activity is investigated by the degradation of Rhodamine B (RhB). The sample of 20 wt% CdS content shows the best photocatalytic performance under visible-light irradiation, with the corresponding RhB degradation rate reaching 97.3%. The excellent photoactivity of CdS HS/g-C3N4 is attributed to the synergistic effect of g-C3N4 and CdS HS. A possible photocatalytic mechanism of the CdS HS/g-C3N4 composite is proposed and corroborated by PL.
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