Co-reporter:Yingchang Jiang, Yun Song, Yanmei Li, Wenchao Tian, Zhichang Pan, Peiyu Yang, Yuesheng Li, Qinfen Gu, and Linfeng Hu
ACS Applied Materials & Interfaces November 1, 2017 Volume 9(Issue 43) pp:37645-37645
Publication Date(Web):October 9, 2017
DOI:10.1021/acsami.7b09373
Two-dimensional LDH nanosheets recently have generated considerable interest in various promising applications because of their intriguing properties. Herein, we report a facile in situ nucleation strategy toward in situ decorating monodispersed Ni–Fe LDH ultrafine nanosheets (UNs) on graphene oxide template based on the precise control and manipulation of LDH UNs anchored, nucleated, grown, and crystallized. Anion-exchange behavior was observed in this Ni–Fe LDH UNs@rGO composite. The Ni–Fe LDH UNs@rGO electrodes displayed a significantly enhanced specific capacitance (2715F g–1 at 3 A g–1) and energy density (82.3 Wh kg–1 at 661 W kg–1), which exceeds the energy densities of most previously reported nickel iron oxide/hydroxides. Moreover, the asymmetric supercapacitor, with the Ni–Fe LDH UNs @rGO composite as the positive electrode material and reduced graphene oxide (rGO) as the negative electrode material, exhibited a high energy density (120 Wh kg –1) at an average power density of 1.3 kW kg –1. A charge transfer from LDH layer to graphene layer, which means a built in electric field directed from LDH to graphene can be established by DFT calculations, which can significantly accelerate reaction kinetics and effectively optimize the capacitive energy storage performance.Keywords: charge transfer; energy storage; interface; layered double hydroxides; ultrafine nanosheets;
Co-reporter:Yun Song;Ziliang Chen;Yanmei Li;Qinchao Wang;Fang Fang;Yong-Ning Zhou;Dalin Sun
Journal of Materials Chemistry A 2017 vol. 5(Issue 19) pp:9022-9031
Publication Date(Web):2017/05/16
DOI:10.1039/C7TA01758H
The high conductivity of bimetallic thiospinel NiCo2S4 endows energy storage devices with very fascinating performance. However, the unsatisfactory rate capability and long-term cyclability of this material series significantly limit their large-scale practical applications such as in electric vehicles and hybrid electric vehicles. Herein, we successfully synthesized NiCo2S4 hexagonal nanosheets with a large lateral dimension of ∼1.35 μm and a thickness of ∼30 nm through a vapor transformation method. The dynamic transformation process of the NiCo2S4 polycrystalline nanosheets from NiCo-hydroxide has been revealed in detail. Originating from their two-dimensional thin-sheet structure with a high aspect ratio, the induced extrinsic capacitive contribution as high as 91% makes them an ideal candidate for high-capacity and high-rate lithium-ion anodes. The NiCo2S4 nanosheets deliver a reversible capacity of 607 mA h g−1 upon 800 cycles at a current density of 2 A g−1. This outstanding long cycle performance sheds light on the structural design of electrode materials for high-rate lithium-ion batteries.
Co-reporter:Yanmei Li;Yun Song;Yingchang Jiang;Mingxiang Hu;Zhichang Pan;Xiaojie Xu;Hongyu Chen;Yuesheng Li;Xiaosheng Fang
Advanced Functional Materials 2017 Volume 27(Issue 23) pp:
Publication Date(Web):2017/06/01
DOI:10.1002/adfm.201701066
Intrinsically p-type conductivity and a wide bandgap of ≈3.6 V endow inorganic delafossite CuGaO2 with great promise for fabricating high-performance UV photodetectors. Nevertheless, CuGaO2-based optoelectronic devices hindered because the intrinsic direct transitions are symmetry forbidden in CuGaO2. This study reports a large-area synthesis of “CuGaO2 nanoplate/ZnS microsphere” heterostructure arrays using a facile solution-based strategy associated with an oil/water interfacial self-assembly approach. It is found that a large number of ZnS microspheres with a polycrystalline structure grow on the top surface of CuGaO2 hexagonal platelets through Ostwald ripening mechanism, forming high-density p–n heterojunctions. A parabolic dependence between the size of ZnS microsphere and the growth time is confirmed in this growth. The UV light adsorption of the heterostructure CuGaO2/ZnS thin film is two times higher than that of the pristine CuGaO2 thin film. Furthermore, the as-designed “CuGaO2 nanoplate/ZnS microsphere” heterostructure arrays exhibit enhanced photoresponse properties. This work offers a new insight into the rational design of optoelectronic devices from the synergetic effect of p-type 2D nanoplates as well as n-type nanostructures such as ZnS, ZnO, CdS, and CdO.
Co-reporter:Mingxiang Hu;Feng Teng;Hongyu Chen;Mingming Jiang;Yuzhu Gu;Hongliang Lu;Xiaosheng Fang
Advanced Functional Materials 2017 Volume 27(Issue 47) pp:
Publication Date(Web):2017/12/01
DOI:10.1002/adfm.201704477
AbstractThe design of nanostructure plays an important role in performance enhancement of low-dimensional optoelectronic devices. Herein, a novel photodetector (PD) based on electrospun SnO2 nanofibers with Ω-shaped ZnO shell (SnO2@ZnO) is fabricated. With 87.4% transmittance at 550 nm, SnO2@ZnO PD exhibits a high photo-to-dark current ratio up to 104 at around 280 nm. Owing to the additional Ω-shaped ZnO shell, SnO2@ZnO PD possesses a responsivity of nearly 100 A W−1 under 5 V bias and the illumination of 250 nm light, which is 30-time enhancement of pristine SnO2 PD. The enhancement is mainly attributed to type-II energy band structure. Furthermore, by changing the direction of incident light, SnO2@ZnO PD has a high UV selectivity with an UV–vis rejection ratio (R250 nm/R400 nm) as much as 2.0 × 103 at 5 V bias under back illumination, which is fourfold higher than that under face illumination. The UV selectivity improvement may be attributed to light confinement in the Ω-shaped structure. With both theoretical simulations and experimental comparisons, it is demonstrated that the unique compact Ω-shaped nanostructure does contribute to photon trapping and gaining process, especially in back-illumination configuration. The approach can be easily extended to other materials, preparing novel building blocks for optoelectronic devices.
Co-reporter:Sancan Han;Ziqi Liang;Swelm Wageh;Ahmed A. Al-Ghamdi;Yongsheng Chen;Xiaosheng Fang
Advanced Functional Materials 2014 Volume 24( Issue 36) pp:5719-5727
Publication Date(Web):
DOI:10.1002/adfm.201401279
There has been significant progress in the field of semiconductor photocatalysis, but it is still a challenge to fabricate low-cost and high-activity photocatalysts because of safety issues and non-secondary pollution to the environment. Here, 2D hexagonal nanoplates of α-Fe2O3/graphene composites with relatively good distribution are synthesized for the first time using a simple, one-step, template-free, hydrothermal method that achieves the effective reduction of the graphene oxide (GO) to graphene and intimate and large contact interfaces of the α-Fe2O3 nanoplates with graphene. The α-Fe2O3/graphene composites showed significantly enhancement in the photocatalytic activity compared with the pure α-Fe2O3 nanoplates. At an optimal ratio of 5 wt% graphene, 98% of Rhodamine (RhB) is decomposed with 20 min of irradiation, and the rate constant of the composites is almost four times higher than that of pure α-Fe2O3 nanoplates. The decisive factors in improving the photocatalytic performance are the intimate and large contact interfaces between 2D hexagonal α-Fe2O3 nanoplates and graphene, in addition to the high electron withdrawing/storing ability and the highconductivity of reduced graphene oxide (RGO) formed during the hydrothermal reaction. The effective charge transfer from α-Fe2O3 nanoplates to graphene sheets is demonstrated by the significant weakening of photoluminescence in α-Fe2O3/graphene composites.
Co-reporter:Jing Huan, Linfeng Hu, and Xiaosheng Fang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 3) pp:1462
Publication Date(Web):January 6, 2014
DOI:10.1021/am4037417
This paper presents a simple and effective oil–water interfacial self-assembly strategy to fabricate monolayer and bilayer nanofilms of densely packed Gd2O3:0.05X3+ (X = Eu, Tb) nanorods with characteristic luminescence properties. In this process, Gd2O3:0.05X3+ (X = Eu, Tb) nanotubes synthesized by a hydrothermal method are dispersed in deionized water; then, a certain amount of n-hexane is added to produce a hexane–water interface. With n-butanol added as initiator, the nanotubes are gradually trapped at the interface to form a densely packed nanofilm. A monolayer nanofilm of densely packed Gd2O3:0.05Eu3+ nanorods is obtained after annealing. In addition, the bilayer nanofilm composed of Gd2O3:0.05X3+ (X = Eu, Tb) nanorods still retains the luminescence properties of each monolayer nanofilm. Moreover, the adhesion of the film on the substrate is very strong, which is extremely beneficial for its future applications.Keywords: bilayer nanofilm; gadolinium hydroxide; gadolinium oxide; interfacial self-assembly; photoluminescence properties;
Co-reporter:Yun Song, Ziliang Chen, Yanmei Li, Qinchao Wang, Fang Fang, Yong-Ning Zhou, Linfeng Hu and Dalin Sun
Journal of Materials Chemistry A 2017 - vol. 5(Issue 19) pp:NaN9031-9031
Publication Date(Web):2017/04/05
DOI:10.1039/C7TA01758H
The high conductivity of bimetallic thiospinel NiCo2S4 endows energy storage devices with very fascinating performance. However, the unsatisfactory rate capability and long-term cyclability of this material series significantly limit their large-scale practical applications such as in electric vehicles and hybrid electric vehicles. Herein, we successfully synthesized NiCo2S4 hexagonal nanosheets with a large lateral dimension of ∼1.35 μm and a thickness of ∼30 nm through a vapor transformation method. The dynamic transformation process of the NiCo2S4 polycrystalline nanosheets from NiCo-hydroxide has been revealed in detail. Originating from their two-dimensional thin-sheet structure with a high aspect ratio, the induced extrinsic capacitive contribution as high as 91% makes them an ideal candidate for high-capacity and high-rate lithium-ion anodes. The NiCo2S4 nanosheets deliver a reversible capacity of 607 mA h g−1 upon 800 cycles at a current density of 2 A g−1. This outstanding long cycle performance sheds light on the structural design of electrode materials for high-rate lithium-ion batteries.
