TiO2 nanocrystals grown on graphene as advanced photocatalytic hybrid materials

Abstract

A graphene/TiO 2 nanocrystals hybrid has been successfully prepared by directly growing TiO 2 nanocrystals on graphene oxide (GO) sheets. The direct growth of the nanocrystals on GO sheets was achieved by a two-step method, in which TiO 2 was first coated on GO sheets by hydrolysis and crystallized into anatase nanocrystals by hydrothermal treatment in the second step. Slow hydrolysis induced by the use of EtOH/H 2 O mixed solvent and addition of H 2 SO 4 facilitates the selective growth of TiO 2 on GO and suppresses growth of free TiO 2 in solution. The method offers easy access to the GO/TiO 2 nanocrystals hybrid with a uniform coating and strong interactions between TiO 2 and the underlying GO sheets. The strong coupling gives advanced hybrid materials with various applications including photocatalysis. The prepared graphene/TiO 2 nanocrystals hybrid has superior photocatalytic activity to other TiO 2 materials in the degradation of rhodamine B, showing an impressive three-fold photocatalytic enhancement over P25. It is expected that the hybrid material could also be promising for various other applications including lithium ion batteries, where strong electrical coupling to TiO 2 nanoparticles is essential. KEYWORDSGraphene, titanium oxide, photocatalyst, hydrolysis Its interesting electrical and mechanical properties, and high surface area make graphene a novel substrate for forming hybrid structures with a variety of nanomaterials [1][2][3]. Graphene hybrids with metal oxides, metals and polymers have been developed recently for various applications [4][5][6]. Nanocrystal growth on graphene sheets is an important approach to produce nanohybrids, since controlled nucleation and growth affords optimal chemical interactions and bonding between nanocrystals and graphene sheets, leading to very strong electrical and mechanical coupling within the hybrid. Several methods have been proposed to form nanocrystals on graphene sheets, such as electrochemical deposition [7], sol-gel process [8] and gas phase deposition [9,10]. Recently, we developed a controlled, two-step solution phase synthesis of nanocrystals of Ni, Fe, and Co hydroxides or oxides on graphene sheets, which is highly selective in that there is no growth of free nanocrystals in solution [1]. We demonstrated the excellent performance of nickel hydroxide nanoplates grown on graphene for electrochemical pseudocapacitive energy storage, utilizing Nano Res. 2010, 3(10): 701-705

Optical visualization of individual ultralong carbon nanotubes by chemical vapour deposition of titanium dioxide nanoparticles

“…Although a series of covalent and non-covalent methods have been reported to deposit metal [26][27][28][29][30] or metal oxide NPs [19][20][21][22][23][24][25][30][31][32][33][34][35][36][37][38][39][40][41][42] on CNTs, most of these methods require the CNTs to be functionalized or modified with surfactants 39,42 , and the processes are conducted in liquid phases 41,42 . These strategies cannot be applied on individual suspended ultralong CNTs because of the fact that they will destroy the suspended CNTs.…”

High specific capacity of TiO2-graphene nanocomposite as an anode material for lithium-ion batteries in an enlarged potential window

“…In addition, graphene is also regarded as an ideal carbon nanostructure to improve the rate capability of TiO 2 owing to its superior electronic conductivity and large surface area. Recently, several TiO 2 -graphene composites have been reported in lithium-ion batteries and other fields [31][32][33][34][35][36][37][38]. For instance, Li et al [31] synthesized mesoporous anatase TiO 2 nanospheres/graphene composites and the composites were applied in lithium-ion batteries and photocatalysis.…”

A brief review of graphene-based material synthesis and its application in environmental pollution management

“…When traditional photocatalysts, such as ZnO, TiO 2 , and CdS, are incorporated with graphene, the hybrid should display high catalytic activity for degradation of organic pollutants because of graphene is a zero-band gap semiconductor. Liang et al [51] synthesized graphene/TiO 2 nanocrystal hybrids by directly growing TiO 2 nanocrystals on graphene oxide nanosheets. First TiO 2 was coated on graphene oxide sheets by hydrolysis, and then the TiO 2 particles were crystallized into anatase nanocrystals by hydrothermal treatment ( Figure 6).…”