photocatalyst material to Bi 2 O 4 showing complete removal of the bacterial cells in
15 min under visible light irradiation. The undecorated BiOBr nanosheets showed
removal of 10
4 CFU mL
À1 bacterial cells within 20 min under the same light due to
doped Bi
5+ acting as electron traps to narrow the bandgap and to enhance the
separation of the photogenerated charges leading to increase the efficiency of the
water disinfection process (Wu et al. 2016a). The same result was also reported by
Wang et al. (2011b). In general, the use of BiO x nanosheets as photocatalyst material
shows a new alternative and methods in the synthesis of two-dimensional
heterojunctions for water disinfection.
Another two-dimensional material that shows multiple advantages in the water
disinfection process with laminar structure is the graphitic carbon nitride as a visible
light photocatalyst (Ong et al. 2016). Recent publications have provided evidence of
graphitic carbon nitride as a photocatalyst for water disinfection due to the various
morphologies, high stability, broad light response spectrum up to 460 nm, and
simple fabrication methods. This gives carbon nitride high feasibility in the water
disinfection process (Deng et al. 2017; Gu et al. 2017; Jiang et al. 2018; Lam et al.
2016; Li et al. 2016c, 2017; Masih et al. 2017; Ong et al. 2016; Song et al. 2016;
Wang et al. 2017a; Wei et al. 2017). However, due to the low surface area and high
recombination rate, it may affect the disinfection process of the pure carbon nitride
(Lam et al. 2016). In this regard, metal or element doping, specific morphology
design, and integration with other components can play a significant role in overcoming the limitations of pure carbon nitride for the water disinfection process. For
instance, according to Huang et al. (2014) in their resaerch to comapre porous
structured graphitic carbon nitride and modified graphitic carbon nitride by adding
elemental silica template using polymerization method with pure graphitic carbon
nitride shows that the porous structured graphitic carbon nitride has higher E. coli
disinfection efficiency than the pure material. This was attributed to the generation of
more active sites in the porous material. Moreover, they showed that during the
designing and fabrication of the porous material, it is difficult to remove the
templated silica after treatment. This opens the possibility to synthesize porous
graphitic carbon nitride nanosheets without a template using thermal etching and
hydrothermal treatment. Their results showed that the synthesis of porous graphitic
carbon nitride nanosheets has removed bacterial cells under visible light within 4 h,
whereas the pure graphitic carbon nitride has removed only 71% of the bacterial cells
within the same time frame. This is due to the large surface area, more active sites,
efficient charge separation, and higher reactive species production leading to
enhanced disinfection process of the porous graphitic carbon nitride nanosheets
compared to pure graphitic carbon nitride (Wang et al. 2017a).
Significant research efforts have been devoted to improving the water disinfection
process by pure graphitic carbon nitride-based materials (g-C 3 N 4 ). Combining
graphitic carbon nitride with different photocatalytic materials such as Bi 2 MoO 6 /
graphitic carbon nitride, Ag/graphitic carbon nitride, graphene/graphitic carbon
nitride, and TiO 2 /graphitic carbon nitride using simple adsorption–deposition
method led to construct composite materials that have more adsorption sites and
224
T. G. Ambaye et al.
15 min under visible light irradiation. The undecorated BiOBr nanosheets showed
removal of 10
4 CFU mL
À1 bacterial cells within 20 min under the same light due to
doped Bi
5+ acting as electron traps to narrow the bandgap and to enhance the
separation of the photogenerated charges leading to increase the efficiency of the
water disinfection process (Wu et al. 2016a). The same result was also reported by
Wang et al. (2011b). In general, the use of BiO x nanosheets as photocatalyst material
shows a new alternative and methods in the synthesis of two-dimensional
heterojunctions for water disinfection.
Another two-dimensional material that shows multiple advantages in the water
disinfection process with laminar structure is the graphitic carbon nitride as a visible
light photocatalyst (Ong et al. 2016). Recent publications have provided evidence of
graphitic carbon nitride as a photocatalyst for water disinfection due to the various
morphologies, high stability, broad light response spectrum up to 460 nm, and
simple fabrication methods. This gives carbon nitride high feasibility in the water
disinfection process (Deng et al. 2017; Gu et al. 2017; Jiang et al. 2018; Lam et al.
2016; Li et al. 2016c, 2017; Masih et al. 2017; Ong et al. 2016; Song et al. 2016;
Wang et al. 2017a; Wei et al. 2017). However, due to the low surface area and high
recombination rate, it may affect the disinfection process of the pure carbon nitride
(Lam et al. 2016). In this regard, metal or element doping, specific morphology
design, and integration with other components can play a significant role in overcoming the limitations of pure carbon nitride for the water disinfection process. For
instance, according to Huang et al. (2014) in their resaerch to comapre porous
structured graphitic carbon nitride and modified graphitic carbon nitride by adding
elemental silica template using polymerization method with pure graphitic carbon
nitride shows that the porous structured graphitic carbon nitride has higher E. coli
disinfection efficiency than the pure material. This was attributed to the generation of
more active sites in the porous material. Moreover, they showed that during the
designing and fabrication of the porous material, it is difficult to remove the
templated silica after treatment. This opens the possibility to synthesize porous
graphitic carbon nitride nanosheets without a template using thermal etching and
hydrothermal treatment. Their results showed that the synthesis of porous graphitic
carbon nitride nanosheets has removed bacterial cells under visible light within 4 h,
whereas the pure graphitic carbon nitride has removed only 71% of the bacterial cells
within the same time frame. This is due to the large surface area, more active sites,
efficient charge separation, and higher reactive species production leading to
enhanced disinfection process of the porous graphitic carbon nitride nanosheets
compared to pure graphitic carbon nitride (Wang et al. 2017a).
Significant research efforts have been devoted to improving the water disinfection
process by pure graphitic carbon nitride-based materials (g-C 3 N 4 ). Combining
graphitic carbon nitride with different photocatalytic materials such as Bi 2 MoO 6 /
graphitic carbon nitride, Ag/graphitic carbon nitride, graphene/graphitic carbon
nitride, and TiO 2 /graphitic carbon nitride using simple adsorption–deposition
method led to construct composite materials that have more adsorption sites and
224
T. G. Ambaye et al.