Preparation of ZnO/graphene heterojunction via high temperature and its photocatalytic property

This paper introduces a novel electrochemical route for preparing the ZnO/graphene heterojunction composite via high temperature. This process includes: (1) depositing the electrochemically reduced graphene oxide (ERGO) on ITO glass via cyclic voltammetry; (2) pulse plating a zinc (Zn) layer on the ERGO; (3) thermally treating the Zn/ERGO composite and “in situ” to obtain the ZnO/ERGO composite. SEM characterizations revealed that the Zinc Oxide (ZnO) particles were homogenously distributed on the surface of graphene sheets. XRD and Raman spectra found a ZnCO3 phase in the ZnO/ERGO composite, which demonstrated that when the Zn film transformed into ZnO particles during thermal treatment, Zn also reacted with graphene and formed a ZnCO3 intermediate layer at the interface between ZnO and ERGO via short-range diffusion. Compared with the heterojunction formed from regular chemical route, the present process provided a tight contact and combination between ZnO and ERGO, which eventually led to a heterojunction between ZnO and graphene sheets. This heterojunction exhibited great improvement for separation efficiency of photo-generate electron–hole pairs. Experimental results of ultraviolet–visible (UV–Vis) light catalysis demonstrated that the photocatalytic activity of the ZnO/ERGO composite had been greatly improved, and exhibited a value of three times higher than that of pure ZnO.

[1]  Zhuo. Sun,et al.  Capacitive behavior of graphene–ZnO composite film for supercapacitors , 2009 .

[2]  Ting Lu,et al.  Microwave-assisted synthesis of graphene–ZnO nanocomposite for electrochemical supercapacitors , 2011 .

[3]  Jung Min Lee,et al.  Inorganic nanostructures grown on graphene layers. , 2011, Nanoscale.

[4]  Xudong Jiang,et al.  A novel route to ZnO/TiO_2 heterojunction composite fibers , 2013 .

[5]  Wen Yu,et al.  Low temperature thermal oxidation synthesis of ZnO nanoneedles and the growth mechanism , 2009 .

[6]  C. Pan,et al.  N + Ni Codoped Anatase TiO2 Nanocrystals with Exposed {001} Facets Through Two‐Step Hydrothermal Route , 2012 .

[7]  Weitao Zheng,et al.  Field Emission from a Composite of Graphene Sheets and ZnO Nanowires , 2009 .

[8]  Y. Nosaka,et al.  Properties of O2.- and OH. formed in TiO2 aqueous suspensions by photocatalytic reaction and the influence of H2O2 and some ions , 2002 .

[9]  Xudong Jiang,et al.  Engineering Nanostructured Bi2WO6–TiO2 Toward Effective Utilization of Natural Light in Photocatalysis , 2011 .

[10]  X. Xia,et al.  A green approach to the synthesis of graphene nanosheets. , 2009, ACS nano.

[11]  Z. Hassan,et al.  Morphological, optical, and Raman characteristics of ZnO nanoflakes prepared via a sol–gel method , 2012 .

[12]  Fabrication and characterization of electrospun TiO2/CuS micro–nano-scaled composite fibers , 2012 .

[13]  K. Chou,et al.  Solid state reaction studies in Fe3O4–TiO2 system by diffusion couple method , 2013 .

[14]  C. J. Smithells,et al.  Smithells metals reference book , 1949 .

[15]  G. Yi,et al.  Vertically aligned ZnO nanostructures grown on graphene layers , 2009 .

[16]  Yongfa Zhu,et al.  Significantly enhanced photocatalytic performance of ZnO via graphene hybridization and the mechanism study , 2011 .

[17]  M. Ozkan,et al.  Heterogeneous graphene nanostructures: ZnO nanostructures grown on large-area graphene layers. , 2010, Small.

[18]  C. Pan,et al.  TiO2/graphene composite from thermal reaction of graphene oxide and its photocatalytic activity in visible light , 2011 .

[19]  P. J. Ollivier,et al.  Layer-by-Layer Assembly of Ultrathin Composite Films from Micron-Sized Graphite Oxide Sheets and Polycations , 1999 .

[20]  Huaqiang Cao,et al.  ZnO@graphene composite with enhanced performance for the removal of dye from water , 2011 .

[21]  Bong Hoon Kim,et al.  Vertical ZnO nanowires/graphene hybrids for transparent and flexible field emission , 2011 .

[22]  X. Qi,et al.  The production of nitrogen-doped graphene from mixed amine plus ethanol flames , 2012 .

[23]  Shixin Wu,et al.  Electrochemical deposition of ZnO nanorods on transparent reduced graphene oxide electrodes for hybrid solar cells. , 2010, Small.

[24]  Jintao Zhang,et al.  Graphene–metal–oxide composites for the degradation of dyes under visible light irradiation , 2011 .

[25]  Aleksandra B. Djurišić,et al.  ZnO nanostructures: growth, properties and applications , 2012 .

[26]  Prashant V Kamat,et al.  Graphene-semiconductor nanocomposites: excited-state interactions between ZnO nanoparticles and graphene oxide. , 2009, Langmuir : the ACS journal of surfaces and colloids.