15 Yet to Be Challenged: TiO 2 as the Photo-Anode Material …
295
Fig. 15.6 Energy band
structure of a DSC utilizing a
TiO 2 composite material for
the photoanode
Generally, there are two methods of preparing the metal composite. One is by
simply mixing the metal and TiO 2 , the other method is immersing TiO 2 in metal
solution and reducing the adsorbed metal ions using either thermal evaporation or
atomic laser deposition. Wu et al. have carried out a method to deposit the silver
nanoparticles by chemical reduction with the aid of NaBH 4 . The highest efficiency
of 5.66% was observed at the highest concentration of NaBH 4 leading to a larger
sized nanoparticle. The silver clusters formed on the surface TiO 2 would act as a
scattering layer reflecting incident light, which increased the photocurrent. In this
study, the dye adsorption was increased by an acid treatment (Wu et al. 2017). Silver
has also been coated on TiO 2 , using photo deposition and an overall efficiency of
6.86% was obtained. The investigators proposed that the silver layer lengthens the
optical pathway and suppresses the charge transfer from surface states (Peng et al.
2013). Chou et al. prepared two composite mixtures containing silver and gold, using
a dry coating method. This study concludes that the doping of metal nanoparticles
improves the overall efficiency but the process of fabrication is very important for
the overall efficiency of the DSC (Chou et al. 2009).
Similar studies have been done incorporating silver and gold as a composite material using a hydrothermal process (Muduli et al. 2012) and one-step electrospinning
process (Nam et al. 2010). Studies have also been done using various nanostructures
of TiO 2 along with metal, such as the use of hierarchical TiO 2 spheres containing needles with gold nanoparticles for a plasmonic enhancement (Bai et al. 2016) and the
use of TiO 2 hollow spheres, nanoparticles, nanosheets with the metal nanoparticles
and nanowires for an enhanced electron transport (Ran et al. 2018).
295
Fig. 15.6 Energy band
structure of a DSC utilizing a
TiO 2 composite material for
the photoanode
Generally, there are two methods of preparing the metal composite. One is by
simply mixing the metal and TiO 2 , the other method is immersing TiO 2 in metal
solution and reducing the adsorbed metal ions using either thermal evaporation or
atomic laser deposition. Wu et al. have carried out a method to deposit the silver
nanoparticles by chemical reduction with the aid of NaBH 4 . The highest efficiency
of 5.66% was observed at the highest concentration of NaBH 4 leading to a larger
sized nanoparticle. The silver clusters formed on the surface TiO 2 would act as a
scattering layer reflecting incident light, which increased the photocurrent. In this
study, the dye adsorption was increased by an acid treatment (Wu et al. 2017). Silver
has also been coated on TiO 2 , using photo deposition and an overall efficiency of
6.86% was obtained. The investigators proposed that the silver layer lengthens the
optical pathway and suppresses the charge transfer from surface states (Peng et al.
2013). Chou et al. prepared two composite mixtures containing silver and gold, using
a dry coating method. This study concludes that the doping of metal nanoparticles
improves the overall efficiency but the process of fabrication is very important for
the overall efficiency of the DSC (Chou et al. 2009).
Similar studies have been done incorporating silver and gold as a composite material using a hydrothermal process (Muduli et al. 2012) and one-step electrospinning
process (Nam et al. 2010). Studies have also been done using various nanostructures
of TiO 2 along with metal, such as the use of hierarchical TiO 2 spheres containing needles with gold nanoparticles for a plasmonic enhancement (Bai et al. 2016) and the
use of TiO 2 hollow spheres, nanoparticles, nanosheets with the metal nanoparticles
and nanowires for an enhanced electron transport (Ran et al. 2018).