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Institution

Nanjing University

EducationNanjing, China
About: Nanjing University is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Catalysis & Population. The organization has 85961 authors who have published 105504 publications receiving 2289036 citations. The organization is also known as: NJU & Nanking University.


Papers
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Journal ArticleDOI
05 Jun 2019-Nature
TL;DR: It is found that freestanding BiFeO3 films exhibit unexpected and giant tetragonality and polarization when approaching the 2D limit, and the absence of a critical thickness for stabilizing the crystalline order in thefreestanding ultrathin oxide films is demonstrated.
Abstract: Two-dimensional (2D) materials such as graphene and transition-metal dichalcogenides reveal the electronic phases that emerge when a bulk crystal is reduced to a monolayer1-4. Transition-metal oxide perovskites host a variety of correlated electronic phases5-12, so similar behaviour in monolayer materials based on transition-metal oxide perovskites would open the door to a rich spectrum of exotic 2D correlated phases that have not yet been explored. Here we report the fabrication of freestanding perovskite films with high crystalline quality almost down to a single unit cell. Using a recently developed method based on water-soluble Sr3Al2O6 as the sacrificial buffer layer13,14 we synthesize freestanding SrTiO3 and BiFeO3 ultrathin films by reactive molecular beam epitaxy and transfer them to diverse substrates, in particular crystalline silicon wafers and holey carbon films. We find that freestanding BiFeO3 films exhibit unexpected and giant tetragonality and polarization when approaching the 2D limit. Our results demonstrate the absence of a critical thickness for stabilizing the crystalline order in the freestanding ultrathin oxide films. The ability to synthesize and transfer crystalline freestanding perovskite films without any thickness limitation onto any desired substrate creates opportunities for research into 2D correlated phases and interfacial phenomena that have not previously been technically possible.

344 citations

Journal ArticleDOI
TL;DR: The mechanism of a newly observed photovoltaic effect which occurs in ferroelectrics with periodic domain structures, found in BiFeO(3) films, is elucidated and should occur in any system with a similar periodic potential.
Abstract: We elucidate the mechanism of a newly observed photovoltaic effect which occurs in ferroelectrics with periodic domain structures. Under sufficiently strong illumination, domain walls function as nanoscale generators of the photovoltaic current. The steps in the electrostatic potential function to accumulate electrons and holes on opposite sides of the walls while locally reducing the concentration of the oppositely charged carriers. As a result, the recombination rate adjacent to the walls is reduced, leading to a net diffusion current. In open circuit, photovoltages for periodically ordered domain walls are additive and voltages much larger than the band gap can be generated. The internal quantum efficiency for individual domain walls can be surprisingly high, approaching 10% for above band-gap photons. Although we have found the effect in BiFeO(3) films, it should occur in any system with a similar periodic potential.

343 citations

Journal ArticleDOI
TL;DR: In this paper, the same authors used U-Pb zircon age, whole-rock chemical and Zircon Hf isotopic data for mafic and felsic igneous rocks to constrain the tectonic evolution of the pre-Devonian Cathaysia block.

343 citations

Journal ArticleDOI
TL;DR: The novel synthesis of 3D graphitic carbon networks through the pyrolysis of nanosized ZIF-67 crystals is reported, which shows excellent electrochemical performance for the insertion and extraction of potassium ions.
Abstract: Three-dimensional (3D) networks of graphitic carbon are promising materials for energy storage and conversion devices because of their high electrical conductivity, which is promoted by the good interconnection between the carbon particles. However, it is still difficult to directly synthesize such carbon networks. Herein, we report the novel synthesis of 3D graphitic carbon networks through the pyrolysis of nanosized ZIF-67 crystals. Interestingly, the unusual effect of downsizing the ZIF-67 crystals and the incorporation of catalytic Co nanoparticles was the spontaneous formation of graphitic networks. The obtained graphitic carbon networks show excellent electrochemical performance for the insertion and extraction of potassium ions.

343 citations

Journal ArticleDOI
TL;DR: In this article, a novel, in situ simultaneous reduction-hydrolysis technique (SRH) is developed for fabrication of TiO2--graphene hybrid nanosheets in a binary ethylenediamine (En)/H2O solvent.
Abstract: A novel, in situ simultaneous reduction-hydrolysis technique (SRH) is developed for fabrication of TiO2--graphene hybrid nanosheets in a binary ethylenediamine (En)/H2O solvent. The SRH technique is based on the mechanism of the simultaneous reduction of graphene oxide (GO) into graphene by En and the formation of TiO2 nanoparticles through hydrolysis of titanium (IV) (ammonium lactato) dihydroxybis, subsequently in situ loading onto graphene through chemical bonds (Ti–O–C bond) to form 2D sandwich-like nanostructure. The dispersion of TiO2 hinders the collapse and restacking of exfoliated sheets of graphene during reduction process. In contrast with prevenient G-TiO2 nanocomposites, abundant Ti3+ is detected on the surface of TiO2 of the present hybrid, caused by reducing agent En. The Ti3+ sites on the surface can serve as sites for trapping photogenerated electrons to prevent recombination of electron–hole pairs. The high photocatalytic activity of G-TiO2 hybrid is confirmed by photocatalytic conversion of CO2 to valuable hydrocarbons (CH4 and C2H6) in the presence of water vapor. The synergistic effect of the surface-Ti3+ sites and graphene favors the generation of C2H6, and the yield of the C2H6 increases with the content of incorporated graphene. The work may open a new doorway for new significant application of graphene for selectively catalytic C–C coupling reaction

343 citations


Authors

Showing all 86514 results

NameH-indexPapersCitations
Yi Chen2174342293080
H. S. Chen1792401178529
Zhenan Bao169865106571
Gang Chen1673372149819
Peter G. Schultz15689389716
Xiang Zhang1541733117576
Rui Zhang1512625107917
Yi Yang143245692268
Markku Kulmala142148785179
Jian Yang1421818111166
Wei Huang139241793522
Bin Liu138218187085
Jun Lu135152699767
Hui Li1352982105903
Lei Zhang135224099365
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20242
2023276
20221,087
20219,130
20208,684
20198,203