He Jiarui

Low platinum loading PtNPs/graphene composite catalyst with high electrocatalytic activity for dye-sensitized solar cells

Platinum nanoparticles (PtNPs)/graphene composite materials are synthesized by a controlled chemical reduction of H2PtCl6 on graphene sheets. The electrocatalytic activity of a PtNPs/graphene composite counter electrode for a dye-sensitized solar cell (DSSC) is investigated. The results demonstrate that the PtNPs/graphene composite has high electrocatalytic activity for the dye-sensitized solar cell. The cell employing PtNPs (1.6 wt%)/graphene counter electrode reaches an conversion efficiency (?) of 3.89% upon the excitation of 100 mW/cm2 AM 1.5 white light, which is comparable to that of the cell with a Pt-film counter electrode (? = 3.76%). It suggests that one can use only 14% Pt content of the conventional Pt-film counter electrode to obtain a comparable conversion efficiency. It may be possible to obtain a high performance DSSC using the PtNPs/graphene composite with a very low Pt content as a counter electrode due to its simplicity, low cost, and large scalability.

Significant photoelectrical response of epitaxial graphene grown on Si-terminated 6H-SiC

Photoelectrical response characteristics of epitaxial graphene (EG) films on Si- and C-terminated 6H-SiC, and transferred chemical vapor deposition (CVD) graphene films on Si-terminated 6H-SiC have been investigated. The results show that upon illumination by a xenon lamp, the photocurrent of EG grown on Si-terminated SiC significantly increases by 147.6%, while the photocurrents of EG grown on C-terminated SiC, and transferred CVD graphene on Si-terminated SiC slightly decrease by 0.5% and 2.7%, respectively. The interfacial buffer layer between EG and Si-terminated 6H-SiC is responsible for the significant photoelectrical response of EG. Its strong photoelectrical response makes it promising for optoelectronic applications.

Temperature dependence of the thickness and morphology of epitaxial graphene grown on SiC (0001) wafers

Epitaxial graphene is synthesized by silicon sublimation from the Si-terminated 6H—SiC substrate. The effects of graphitization temperature on the thickness and surface morphology of epitaxial graphene are investigated. X-ray photoelectron spectroscopy spectra and atomic force microscopy images reveal that the epitaxial graphene thickness increases and the epitaxial graphene roughness decreases with the increase in graphitization temperature. This means that the thickness and roughness of epitaxial graphene films can be modulated by varying the graphitization temperature. In addition, the electrical properties of epitaxial graphene film are also investigated by Hall effect measurement.