Solar Hydrogen Generation: Photocatalytic and Photoelectrochemical Methods - Hydrogen Generation, Storage, and Utilization - page 33

(a)

(b)

(d)

(c)

FIGURE 3.2 (a-b) TEM images of GaP nanowires. The inset in (a) shows the indexed FFT pattern of
the image, indicating the wire is a single crystal with a growth axis of [111] direction. (c) Photograph of
a large GaP nanowire membrane on a PVDF ilter membrane. Source : Reproduced with permission from
Sun et al. [18]. (See color insert.)

eficiently suppress charge recombination by facilitating charge transfer of
the photoexcited carriers. The CdS-graphene composite was prepared using
a solvothermal method in which graphene oxide and cadmium acetate
are the precursors of graphene and CdSe, respectively [30]. TEM images
showed that the graphene sheets were decorated with many small particles
(Fig. 3.3a), and these particles are single crystals with an average size of
around 3 nm [30]. The CdS-graphene composite was further modiied with
Pt catalyst for hydrogen evolution. Figure 3.3c illustrates the three possible
mechanisms of electron transfer on the composite under visible light irradia-
tion: (1) to Pt nanoparticles deposited on the surface of CdS cluster; (2) to