three main peaks. The residual of small organic intermediates can explain the
changing of color solution as well as the decrease of pH.
10.2.2 Modification of Bi2compounds
Although BiÀcompounds were introduced as visible light-responsive photocatalyts
in water treatment, some compounds such as BiFeO 3 and BiOXs have weak
adsorption ability which led to poor performance for photocatalytic degradation of
pollutants. Relatively poor efficiency can attribute to (i) high recombination rate of
electronÀhole in bulk or surface, (ii) positions of conduction band or valence band
related to O 2 reduction or H 2 O oxidation, respectively, and (iii) small surface area for
photocatalytic process. So far, many researches were devised for resolving the
problematic issues such as morphology modifications, doping, and heterojunctions
(Chen et al. 2016a) with other semiconductors and generation of vacancies over the
surface. Applying the solutions, either the recombination rate or light harvesting can
be effectively decreased or increased, respectively, which led to high performance.
For more clearance, follow the more detailed discussion below.
Morphology Control
The chemophysical properties of semiconductors could be changed by main structural factors, size, morphology, and defects, respectively. Subsequently,
photocatalytic properties of catalysts can improve by the structural parameters. In
this section, we are focused on morphology control of BiÀcompounds and investigated photocatalytic performance. Morphology studies were shown improved
photocatalytic efficiency because of produce low-dimensional or hierarchical structures, which could create reactive sites, high rate of mass transfer, and more
harvesting amount of visible light. In the following, some more innovative
producting techniques of low-dimensional and hierarchical structures of
BiÀcompounds were discussed.
Bi-compounds with Low-Dimensional Structure
Nanomaterials have multifarious dimensions which could be classified to four
categories: zero-dimension such as nanoparticles, one-dimension such as nanorods
and nanowires, two-dimension such as nanoplates or nanosheets, and threedimension such as nanospheres or nanoflowers (Jeevanandam et al. 2018). At the
recent years, BiÀcompounds were synthesized by control of synthetization parameters to obtain special size including nanoparticles, nanobelts, and nanoflowers for
photocatalytic applications. Soltani et al. (Soltani and Entezari 2013b, c) reported
that BiFeO 3 nanoparticles synthesized via ultrasound with narrow size distribution
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M. Zargazi and M. Chahkandi
changing of color solution as well as the decrease of pH.
10.2.2 Modification of Bi2compounds
Although BiÀcompounds were introduced as visible light-responsive photocatalyts
in water treatment, some compounds such as BiFeO 3 and BiOXs have weak
adsorption ability which led to poor performance for photocatalytic degradation of
pollutants. Relatively poor efficiency can attribute to (i) high recombination rate of
electronÀhole in bulk or surface, (ii) positions of conduction band or valence band
related to O 2 reduction or H 2 O oxidation, respectively, and (iii) small surface area for
photocatalytic process. So far, many researches were devised for resolving the
problematic issues such as morphology modifications, doping, and heterojunctions
(Chen et al. 2016a) with other semiconductors and generation of vacancies over the
surface. Applying the solutions, either the recombination rate or light harvesting can
be effectively decreased or increased, respectively, which led to high performance.
For more clearance, follow the more detailed discussion below.
Morphology Control
The chemophysical properties of semiconductors could be changed by main structural factors, size, morphology, and defects, respectively. Subsequently,
photocatalytic properties of catalysts can improve by the structural parameters. In
this section, we are focused on morphology control of BiÀcompounds and investigated photocatalytic performance. Morphology studies were shown improved
photocatalytic efficiency because of produce low-dimensional or hierarchical structures, which could create reactive sites, high rate of mass transfer, and more
harvesting amount of visible light. In the following, some more innovative
producting techniques of low-dimensional and hierarchical structures of
BiÀcompounds were discussed.
Bi-compounds with Low-Dimensional Structure
Nanomaterials have multifarious dimensions which could be classified to four
categories: zero-dimension such as nanoparticles, one-dimension such as nanorods
and nanowires, two-dimension such as nanoplates or nanosheets, and threedimension such as nanospheres or nanoflowers (Jeevanandam et al. 2018). At the
recent years, BiÀcompounds were synthesized by control of synthetization parameters to obtain special size including nanoparticles, nanobelts, and nanoflowers for
photocatalytic applications. Soltani et al. (Soltani and Entezari 2013b, c) reported
that BiFeO 3 nanoparticles synthesized via ultrasound with narrow size distribution
334
M. Zargazi and M. Chahkandi