CuO/Ag photocatalyst involving precipitation of spherical Ag nanoparticles over
needle-shaped CuO and curcumin as the functionalization and reducing agent for
aerobic eradication of methyl orange dye. The photodegradation mechanism follows
Z-scheme-assisted improved electron–hole pair separation as depicted in Fig. 4.3
which involves transference of electrons from conduction band of CuO semiconductor via Ag mediator valence band of curcumin (Kumar et al. 2019a, b).
In another study, cotton-like CuO microstructures were synthesized by ultrasonic- assisted technique, which showed 95% disintegration of reactive black-5 dye
under visible radiation (Rao et al. 2018). The reactive black-5 is extensively utilized
in textile industry for coloring the fabrics. The continuous exposure to reactive
black-5 may cause allergic or asthma problem. A possible degradation mechanism
was confirmed by liquid chromatography–mass spectrometry (Fig. 4.5).
Mandal et al. (2019) fabricated an evenly dispersed Fe 2 O 3 on the surface of SiO 2
via a sol–gel process involving 88% congo red dye degradation in 180 min with
absorption in the range of 560 nm. SiO 2 decorated with Co core shell have been
vulnerably used to degrade congo red and methyl orange. Nearly, 95% methyl
orange was degraded, whereas only 82% of congo red dye at 565 nm indicating
the complexity due to the presence of two (ÀN¼N) which requires large concentration of synthesized photocatalyst for degradation (Zhang et al. 2016). Semiconductor quantum dots have been anchored with cadmium sulfide (CdS) photocatalyst
prepared via heat quench treatment for effective removal of methyl orange dye.
Another way is to fabricate a nanoparticles with carbonaceous material as support
that canhelp to solve its leaching problem, lower rate of recombination and make it
visible light-active photocatalyst so as to achieve high efficiency for the removal of
pollutant and many more. Fabrication of heterojunction depends upon the band edge
position of the two combining semiconductors which also assist in upconversion
photoluminescence. Heterojunction formation will help to slower down the rate of
recombination as charge carrier will spent more time apart, to carry out reduction and
oxidation.
4.3 Ternary Photocatalyst for Azo Dye Degradation
Wu et al. (2019) synthesized ZnO/Fe 3 O 4 /g-C 3 N 4 ternary nanocomposites which is a
visible light-induced and easily recoverable photocatalyst. ZnO/Fe 3 O 4 /g-C 3 N 4 were
employed for the degradation of monas dye and observed remarkable upgraded in
photocatalytic activity of ZnO/Fe 3 O 4 /g-C 3 N 4 as compared to pure graphitic carbon
nitride and ZnO nanoparticle. Heterojunction of ZnO/Fe 3 O 4 /g-C 3 N 4 displayed
higher absorption of visible radiation and enhanced charge separation efficiency.
The stability experiment exposed that ZnO/Fe 3 O 4 /g-C 3 N 4 –50% nanocomposites
exhibited comparatively more photodegradation activity after 5 recycles. 97.87%,
98.05%, and 83.35% degradation efficiency was observed for methyl orange, alizarin yellow R, and orange G, respectively via ZnO/Fe 3 O 4 /g-C 3 N 4 . High
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P. Shandilya et al.
needle-shaped CuO and curcumin as the functionalization and reducing agent for
aerobic eradication of methyl orange dye. The photodegradation mechanism follows
Z-scheme-assisted improved electron–hole pair separation as depicted in Fig. 4.3
which involves transference of electrons from conduction band of CuO semiconductor via Ag mediator valence band of curcumin (Kumar et al. 2019a, b).
In another study, cotton-like CuO microstructures were synthesized by ultrasonic- assisted technique, which showed 95% disintegration of reactive black-5 dye
under visible radiation (Rao et al. 2018). The reactive black-5 is extensively utilized
in textile industry for coloring the fabrics. The continuous exposure to reactive
black-5 may cause allergic or asthma problem. A possible degradation mechanism
was confirmed by liquid chromatography–mass spectrometry (Fig. 4.5).
Mandal et al. (2019) fabricated an evenly dispersed Fe 2 O 3 on the surface of SiO 2
via a sol–gel process involving 88% congo red dye degradation in 180 min with
absorption in the range of 560 nm. SiO 2 decorated with Co core shell have been
vulnerably used to degrade congo red and methyl orange. Nearly, 95% methyl
orange was degraded, whereas only 82% of congo red dye at 565 nm indicating
the complexity due to the presence of two (ÀN¼N) which requires large concentration of synthesized photocatalyst for degradation (Zhang et al. 2016). Semiconductor quantum dots have been anchored with cadmium sulfide (CdS) photocatalyst
prepared via heat quench treatment for effective removal of methyl orange dye.
Another way is to fabricate a nanoparticles with carbonaceous material as support
that canhelp to solve its leaching problem, lower rate of recombination and make it
visible light-active photocatalyst so as to achieve high efficiency for the removal of
pollutant and many more. Fabrication of heterojunction depends upon the band edge
position of the two combining semiconductors which also assist in upconversion
photoluminescence. Heterojunction formation will help to slower down the rate of
recombination as charge carrier will spent more time apart, to carry out reduction and
oxidation.
4.3 Ternary Photocatalyst for Azo Dye Degradation
Wu et al. (2019) synthesized ZnO/Fe 3 O 4 /g-C 3 N 4 ternary nanocomposites which is a
visible light-induced and easily recoverable photocatalyst. ZnO/Fe 3 O 4 /g-C 3 N 4 were
employed for the degradation of monas dye and observed remarkable upgraded in
photocatalytic activity of ZnO/Fe 3 O 4 /g-C 3 N 4 as compared to pure graphitic carbon
nitride and ZnO nanoparticle. Heterojunction of ZnO/Fe 3 O 4 /g-C 3 N 4 displayed
higher absorption of visible radiation and enhanced charge separation efficiency.
The stability experiment exposed that ZnO/Fe 3 O 4 /g-C 3 N 4 –50% nanocomposites
exhibited comparatively more photodegradation activity after 5 recycles. 97.87%,
98.05%, and 83.35% degradation efficiency was observed for methyl orange, alizarin yellow R, and orange G, respectively via ZnO/Fe 3 O 4 /g-C 3 N 4 . High
130
P. Shandilya et al.