Jianguo Hou

Low-Temperature Growth of Graphene by Chemical Vapor Deposition Using Solid and Liquid Carbon Sources

Graphene has attracted a lot of research interest owing to its exotic properties and a wide spectrum of potential applications. Chemical vapor deposition (CVD) from gaseous hydrocarbon sources has shown great promises for large-scale graphene growth. However, high growth temperature, typically 1000 °C, is required for such growth. Here we demonstrate a revised CVD route to grow graphene on Cu foils at low temperature, adopting solid and liquid hydrocarbon feedstocks. For solid PMMA and polystyrene precursors, centimeter-scale monolayer graphene films are synthesized at a growth temperature down to 400 °C. When benzene is used as the hydrocarbon source, monolayer graphene flakes with excellent quality are achieved at a growth temperature as low as 300 °C. The successful low-temperature growth can be qualitatively understood from the first principles calculations. Our work might pave a way to an undemanding route for economical and convenient graphene growth.

Site-specific photocatalytic splitting of methanol on TiO2(110).

Clean hydrogen production is highly desirable for future energy needs, making the understanding of molecular-level phenomena underlying photocatalytic hydrogen production both fundamentally and practically important. Water splitting on pure TiO2 is inefficient, however, adding sacrificial methanol could significantly enhance the photocatalyzed H2 production. Therefore, understanding the photochemistry of methanol on TiO2 at the molecular level could provide important insights to its photocatalytic activity. Here, we report the first clear evidence of photocatalyzed splitting of methanol on TiO2 derived from time-dependent two-photon photoemission (TD-2PPE) results in combination with scanning tunneling microscopy (STM). STM tip induced molecular manipulation before and after UV light irradiation clearly reveals photocatalytic bond cleavage, which occurs only at Ti4+ surface sites. TD-2PPE reveals that the kinetics of methanol photodissociation is clearly not of single exponential, an important characteristic of this intrinsically heterogeneous photoreaction.

Gold‐Based Hybrid Nanocrystals Through Heterogeneous Nucleation and Growth

[*] Dr. J. Zeng, Prof. X. Wang, Prof. J. Hou, Prof. S. Zhang, J. Huang, C. Liu, C. H. Wu, Y. Lin Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China Hefei, Anhui 230026 (P. R. China) E-mail: jzeng@mail.ustc.edu.cn; xpwang@ustc.edu.cn; jghou@ustc.edu.cn Prof. Y. Xia, Dr. J. Zeng Department of Biomedical Engineering Washington University St. Louis, MO 63130 (USA)

A simple solution route to ZnS nanotubes and hollow nanospheres and their optical properties

This paper describes a simple solution route to ZnS nanotubes assisted by CNTs and to ZnS hollow nanospheres by templating with inxa0situ generated bubbles at low temperature. Two types of nanotube exist. One has two open ends with a very thin wall; the other has a sealed end with a thicker wall. The hollow nanospheres have uniform thickness of xa0nm and they formed dynamically controlled by the quantity of water. HREM results reveal that the nanotubes and hollow nanospheres are both composed of ZnS nanoparticles. The UV–vis absorption spectra exhibit large blue shifts because of quantum size effects. These hollow structures may have potential applications in some areas.

Charge transfer and retention in directly coupled Au-CdSe nanohybrids

AbstractThe energy and charge transfer dynamics of directly coupled Au-CdSe hybrid nanocrystals have been studied using time-resolved photoluminescence (PL) techniques. The PL of such nanohybrids was found to be quenched dramatically compared to that of both CdSe quantum dots and mixtures of CdSe quantum dots with Au nanoparticles. Fluorescence decay curves of the Au-CdSe nanohybrids show three distinct decay channels with the fastest one associated with the transfer of electrons from the CdSe portion to the Au portion. The holes on the CdSe portion created by such charge transfer were then quickly taken away by the solution, while the electrons on the Au portion slowly leaked into the solution as well, thus serving as a reductant for redox reactions. Using a model reaction based on the reduction of methylene blue by the leaking electrons, our photocatalytic experiments indicate that the electrons can be temporarily retained in the Au portion (most likely at the Au-capping agent interface) for a dramatically long timescale, up to 100 min. Finally, by merging all of the observations in the time-resolved PL measurements, we were able to figure out a relatively complete picture of charge transfer and retention in the Au-CdSe nanohybrids. This picture is expected to guide researchers in designing modern photocatalysts and solar cells constructed from nanoscale metal-semiconductor hybrids.n

CO2dissociation activated through electron attachment on the reduced rutile TiO2(110)-1×1 surface

Converting CO

Electronic structure of bilayer graphene: A real-space Green's function study

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High pressure photoluminescence of CdZnSe quantum dots : Alloying effect

to useful compounds through the solar photocatalytic reduction has been one of the most promising strategies for artificial carbon recycling. The highly relevant photocatalytic substrate for CO

Controlling Electronic States and Transport Properties at the Level of Single Molecules

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UV-Light Induced Fabrication of CdCl2 Nanotubes through CdSe/Te Nanocrystals Based on Dimension and Configuration Control

conversion has been the popular TiO