Xiaopeng Zeng

Photocatalytic water splitting to hydrogen production of reduced graphene oxide/SiC under visible light

We report a method to realize the H2 production and graphene-oxide (GO) reduction simultaneously over GO/SiC composite under visible light irradiation with KI as sacrifice reagent. The weight content of GO is regulated in the reaction system. The rate of H2 production reaches to 95u2009μL/h with 1% GO content in GO/SiC composite system, which is 1.3 times larger compared to the case in pure SiC NPs under visible light. The reduced-GO sheet can serve as an electron collector and transporter to efficiently separate the photo-generated electron-hole pairs, lengthening the lifetime of the charge carriers effectively.

Preparation of single- and few-layer graphene sheets using co deposition on SiC substrate

Single- and few-layer graphene sheets were fabricated by selective chemical reactions between Co film and SiC substrate. A rapid cooling process was employed. The number of layers and crystallinity of graphene sheets were controlled by process parameters. The formation mechanism of graphene was highly sensitive to carbon diffusion. Free carbon precipitated and then moved across the product layer that was composed mainly of cobalt-silicides. The graphene layer formed homogeneously on the surface and then transferred to the other substrate. This could provide a method for high-quality fabrication of wafer-sized graphene sheets.

Investigation of Ta/Ni bilayered ohmic contacts on n-type SiC single-crystal substrate

The interfacial reactions between a Ta/Ni bilayered film and SiC single-crystal substrate during annealing at 650–1,100xa0°C were investigated. It was found that H-Ni2Si (hexagonal Ni2Si) and TaC formed at the interface as a result of thermal annealing. A small amount of free C atoms diffused outwards the surface, leading to the formation of carbon vacancies that could act as electron donors. The electrical properties of the contacts showed that ohmic behavior was observed for the sample annealed above 800xa0°C. The specific contact resistivity was determined to be as low as 4.4xa0×xa010−4xa0Ωxa0cm2 at 1,100xa0°C.Graphical abstract

Erratum: “Photocatalytic water splitting to hydrogen production of reduced graphene oxide/SiC under visible light” [Appl. Phys. Lett. 102, 083101 (2013)]

(1) Department of Chemistry, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China

Homogeneous dispersion of high-conductive reduced graphene oxide sheets for polymethylmethacrylate nanocomposites

The high cohesive interaction between reduced graphene oxide (RGO) sheets usually makes them difficult to disperse, which limits their utilization in achieving effective hybridization with polymers. We report here a new two-step route for preparing non-aggregated and high-conductive RGO powders. Graphene oxide precursor was first reduced by hydrazine hydrate in presence of a thermal unstable surfactant of cetyltrimethylammonium chloride (CTAC). Then a thermal annealing process under H 2 /Ar atmosphere was further used to remove the non-conductive CTAC molecules. The prepared RGO powder exhibited an electrical conductivity of 2.23xa0×xa010 4 xa0Sxa0m −1 – about ten times higher than the one (N-RGO) simply reduced by hydrazine hydrate. After incorporating into polymethylmethacrylate with a 5xa0wt% loading, the composite showed a conductivity of 4.11xa0Sxa0m −1 , which was 60 times as high as that of the same composite based on N-RGO powder. The addition and subsequent removal of CTAC molecules is an effective method for preparing non-aggregated and highly conductive graphene powder and obtaining good incorporation into polymer matrices.

Erratum: Photocatalytic water splitting to hydrogen production of reduced graphene oxide/SiC under visible light (Applied Physics Letters (2013) 102 (083101))

(1) Department of Chemistry, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China

Photocatalytic water splitting to hydrogen production of reduced graphene oxide/SiC under visible light (vol 102, 083101, 2013)

(1) Department of Chemistry, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China

Surface morphology and electrical property evolution of super-thin Pt film on 6H-SiC substrate during annealing

We reported the surface morphology and electrical property of super-thin Pt films, ∼2 nm thick, deposited on 6 H -SiC (0001) substrates and subsequently annealed from 400 to 1000 °C. The surfaces of the films were found to have a feature of islands growth, and the sizes of the islands increased with increasing annealing temperature. Free carbon, produced by selective reactions between Pt and SiC, diffused toward the top surface across the product layers due to low solubility and composition gradient of carbon throughout the reaction zone. A dramatic change of electrical conductivity of the films was observed. A mechanism analysis reveals that the origin came from the contribution of aggregation of islands on the surface and formation of Pt silicides and a thin layer of crystalline graphite.