Designing Novel Photocatalysts for Disinfection of Multidrug-Resistant …
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Ag NPs resulting in delayed electron–hole recombination and better photocatalytic
yield. This has been confirmed by other studies too. ZnO has been once considered as the most appropriate alternative for TiO 2 and photocatalytic applications.
Sulphonated GO with ZnO nanorods along with Ag could have greater photocatalytic
inactivation activity toward E. coli cells than their two-component counterparts like
of SGO–ZnO, and ZnO–Ag. Also CdS is recognized as an excellent photocatalyst
under visible light. Thus, efforts were use them in graphene-based composites were
accomplished by a novel two-phase mixing method. Their visible light PCD performance was evaluated against Gram-negative E. coli and Gram-positive B. subtilis.
The composite was reported to achieve 100% disinfection of E. coli and about 90%
of B. subtilis in 20 and 10 min, respectively (Zhao et al. 2013). This efficiency is
better than their lone counterparts, i.e., CdS and GO individually. The much detrimental action on Gram-positive bacteria is attributed to the lack of additional outer
membrane in them unlike Gram-negative bacteria, which usually can protect the
inner peptidoglycan layer from reactive oxygen species-mediated peroxidation (Ong
et al. 2015). On another instance, reduced graphene oxide (RGO)-modified with
Bi 2 MoO 6 nanoplates using hydrothermal treatment possess superior uniformity and
ordered orientation of their active lattice (Ong et al. 2015). They were reported to
have better visible light PCD against E. coli, i.e., nearly 5-log reduction in 3 h, where
Bi 2 MoO 6 failed in even 4 h with just 2-log reduction. The better PCD efficiency with
oxide (RGO)-modified with Bi 2 MoO 6 was attributed to effective charge transfer from
Bi 2 MoO 6 to graphene (Zhang et al. 2013).
2.5 Nonmetallic Materials Graphitic Carbon Nitride
Polymeric graphitic carbon nitride (g-C 3 N 4 ) has been the major source of photocatalytic attraction in the modern era (Ong et al. 2016). The presence of heptazine
ring structure and a great degree of condensation serves advantages related to good
physicochemical stability, attractive electronic structure with a bandgap of 2.7 eV,
making it sunlight or visible light responsive (Wang et al. 2015). With the ease of
preparation involving thermal polycondensation of the less expensive N-rich precursors, like cyanamide (Lei et al. 2015), urea (Lei et al. 2015), thiourea (Lei et al. 2015),
melamine (Shan et al. 2016), and dicyandiamide, they can be suitable candidates in
water splitting and PCD of harmful coliform waterborne and MDR bacteria.
The photocatalytic efficiency of such materials for the disinfection of E.coli
was first reported by Huang et al. They reported that the mesoporous form of gC 3 N 4 with surface area nearly equal to 230 m
2 /g, resulted complete disinfection of
the E. coli K-12 in presence of sunlight in less than 4 h time (Huang et al. 2014).
Pure g-C 3 N 4 endures inadequacy as a suitable photocatalyst due to faster recombination of electron–hole pairs, lesser specific surface area, and lower visible light
utilization (Zhang et al. 2012). Thus, researchers are focussing on layering the bulk
g-C 3 N 4 into nanosheets for better photocatalytic activity. Evidences from Zhao et al.
(2014), where a 0.5 nm thick single layer g-C 3 N 4 nanosheets using thermal etching
461
Ag NPs resulting in delayed electron–hole recombination and better photocatalytic
yield. This has been confirmed by other studies too. ZnO has been once considered as the most appropriate alternative for TiO 2 and photocatalytic applications.
Sulphonated GO with ZnO nanorods along with Ag could have greater photocatalytic
inactivation activity toward E. coli cells than their two-component counterparts like
of SGO–ZnO, and ZnO–Ag. Also CdS is recognized as an excellent photocatalyst
under visible light. Thus, efforts were use them in graphene-based composites were
accomplished by a novel two-phase mixing method. Their visible light PCD performance was evaluated against Gram-negative E. coli and Gram-positive B. subtilis.
The composite was reported to achieve 100% disinfection of E. coli and about 90%
of B. subtilis in 20 and 10 min, respectively (Zhao et al. 2013). This efficiency is
better than their lone counterparts, i.e., CdS and GO individually. The much detrimental action on Gram-positive bacteria is attributed to the lack of additional outer
membrane in them unlike Gram-negative bacteria, which usually can protect the
inner peptidoglycan layer from reactive oxygen species-mediated peroxidation (Ong
et al. 2015). On another instance, reduced graphene oxide (RGO)-modified with
Bi 2 MoO 6 nanoplates using hydrothermal treatment possess superior uniformity and
ordered orientation of their active lattice (Ong et al. 2015). They were reported to
have better visible light PCD against E. coli, i.e., nearly 5-log reduction in 3 h, where
Bi 2 MoO 6 failed in even 4 h with just 2-log reduction. The better PCD efficiency with
oxide (RGO)-modified with Bi 2 MoO 6 was attributed to effective charge transfer from
Bi 2 MoO 6 to graphene (Zhang et al. 2013).
2.5 Nonmetallic Materials Graphitic Carbon Nitride
Polymeric graphitic carbon nitride (g-C 3 N 4 ) has been the major source of photocatalytic attraction in the modern era (Ong et al. 2016). The presence of heptazine
ring structure and a great degree of condensation serves advantages related to good
physicochemical stability, attractive electronic structure with a bandgap of 2.7 eV,
making it sunlight or visible light responsive (Wang et al. 2015). With the ease of
preparation involving thermal polycondensation of the less expensive N-rich precursors, like cyanamide (Lei et al. 2015), urea (Lei et al. 2015), thiourea (Lei et al. 2015),
melamine (Shan et al. 2016), and dicyandiamide, they can be suitable candidates in
water splitting and PCD of harmful coliform waterborne and MDR bacteria.
The photocatalytic efficiency of such materials for the disinfection of E.coli
was first reported by Huang et al. They reported that the mesoporous form of gC 3 N 4 with surface area nearly equal to 230 m
2 /g, resulted complete disinfection of
the E. coli K-12 in presence of sunlight in less than 4 h time (Huang et al. 2014).
Pure g-C 3 N 4 endures inadequacy as a suitable photocatalyst due to faster recombination of electron–hole pairs, lesser specific surface area, and lower visible light
utilization (Zhang et al. 2012). Thus, researchers are focussing on layering the bulk
g-C 3 N 4 into nanosheets for better photocatalytic activity. Evidences from Zhao et al.
(2014), where a 0.5 nm thick single layer g-C 3 N 4 nanosheets using thermal etching