25 mg rGO is dispersed in 40 mg H-C 3 N 4 with 0.25 g FeCl 3 .6H 2 O followed by
stirring, ultracentrifugation, and drying on oven at 70
C for 12 h. Feng et al. (2019)
performed a pyrolysis approach for the synthesis of silver (Ag)-anchored g-C 3 N 4 /
Fe 2 O 3 to study photocatalytic and antibacterial activities. The process followed
addition of 0.02 g laponite to 0.01 g FeNO 3 .9H 2 O with dropwise addition of
0.05 g silver nitrate (AgNO 3 ). The mixture was heated at 400
C for 10 min in a
muffle furnace to obtain Ag-mediated g-C 3 N 4 /Fe 2 O 3 . A ternary heterojunction
comprising of Fe 2 O 3 -decorated ZnO/g-C 3 N 4 was fabricated using precursors urea,
zinc acetate dihydrate, and ferric oxyhydroxide (FeO (OH)). g-C 3 N 4 was prepared
by heating urea in a covered crucible at 550
C followed by pyrolysis process,
whereas a sol–gel method was employed for fabrication of nanocomposite by Balu
et al. (2019). Ren et al. (2019) opted a one-step annealing process for synthesis of an
octahedron hybrid with 3 g melamine and 0.3 g FeCl 3 controlled by
polyvinylpyrrolidone. Wang et al. (2019) exemplified synergistic effect of incorporation of dopant manganese (Mn) in g-C 3 N 4 /Fe 2 O 3 heterojunction. The procedure
involved addition of 0.15 g manganese chloride (MnCl 2 .4H 2 O) to 2 g FeCl 3 .6H 2 O,
thermal polymerization of precursors to form Mn-doped Fe 2 O 3 , and heating 10 g of
urea at 550
C in N 2 atmosphere for preparation of g-C 3 N 4 .
The usage of solvents at low temperature has proven to be a more economical
synthesis strategy. Pant et al. (2017) performed facile one-step hydrothermal with
precursors melamine, FeCl 3 .4H 2 O, and AgNO 3 and obtained Ag-mediated g-C 3 N 4 /
Fe 2 O 3 . Xu et al. (2014) developed an ionic liquid system with precursors
dicyanamide, FeCl 3 , and 1-Butyl-3-methylimidazolium chloride via solvothermal
process at low temperature. Theerthagiri et al. (2014) performed wet impregnation
experiment utilizing precursors Fe (NO 3 ) 3 .9H 2 O and citric acid (1:3) with constant
stirring and drying at 95
C followed by addition of urea. The abovementioned
discussions on synthesis strategies give a comparative overview of low- and hightemperature-driven methods.
2.2.1 g-C 3 N 4 /Fe 2 O 3 Heterojunction Photocatalyst
for Removal of Recalcitrant Pollutants
Among the countless properties exhibited by magnetic oxides, its large specific
surface area with ample number of reactive sites makes it available for anchoring
of pollutants. Additionally, its cost-effective nature and suitable bandgap of 2.2 eV
with regeneration ability exhibit more pronouncing effect for photodegradation of
pollutants. It is clearly apparent from review of literature that researchers have been
constantly exploiting the inherent properties of Fe 2 O 3 and g-C 3 N 4 photocatalyst for
water treatment purpose.
Babar et al. (2019) prepared g-C 3 N 4 /Fe 2 O 3 from waste toner powder
nanocomposite which exhibited 85% and 82% elimination of methyl orange dye
and textile effluents, respectively. X-ray diffraction studies confirmed that on
60
P. Raizada et al.
stirring, ultracentrifugation, and drying on oven at 70
C for 12 h. Feng et al. (2019)
performed a pyrolysis approach for the synthesis of silver (Ag)-anchored g-C 3 N 4 /
Fe 2 O 3 to study photocatalytic and antibacterial activities. The process followed
addition of 0.02 g laponite to 0.01 g FeNO 3 .9H 2 O with dropwise addition of
0.05 g silver nitrate (AgNO 3 ). The mixture was heated at 400
C for 10 min in a
muffle furnace to obtain Ag-mediated g-C 3 N 4 /Fe 2 O 3 . A ternary heterojunction
comprising of Fe 2 O 3 -decorated ZnO/g-C 3 N 4 was fabricated using precursors urea,
zinc acetate dihydrate, and ferric oxyhydroxide (FeO (OH)). g-C 3 N 4 was prepared
by heating urea in a covered crucible at 550
C followed by pyrolysis process,
whereas a sol–gel method was employed for fabrication of nanocomposite by Balu
et al. (2019). Ren et al. (2019) opted a one-step annealing process for synthesis of an
octahedron hybrid with 3 g melamine and 0.3 g FeCl 3 controlled by
polyvinylpyrrolidone. Wang et al. (2019) exemplified synergistic effect of incorporation of dopant manganese (Mn) in g-C 3 N 4 /Fe 2 O 3 heterojunction. The procedure
involved addition of 0.15 g manganese chloride (MnCl 2 .4H 2 O) to 2 g FeCl 3 .6H 2 O,
thermal polymerization of precursors to form Mn-doped Fe 2 O 3 , and heating 10 g of
urea at 550
C in N 2 atmosphere for preparation of g-C 3 N 4 .
The usage of solvents at low temperature has proven to be a more economical
synthesis strategy. Pant et al. (2017) performed facile one-step hydrothermal with
precursors melamine, FeCl 3 .4H 2 O, and AgNO 3 and obtained Ag-mediated g-C 3 N 4 /
Fe 2 O 3 . Xu et al. (2014) developed an ionic liquid system with precursors
dicyanamide, FeCl 3 , and 1-Butyl-3-methylimidazolium chloride via solvothermal
process at low temperature. Theerthagiri et al. (2014) performed wet impregnation
experiment utilizing precursors Fe (NO 3 ) 3 .9H 2 O and citric acid (1:3) with constant
stirring and drying at 95
C followed by addition of urea. The abovementioned
discussions on synthesis strategies give a comparative overview of low- and hightemperature-driven methods.
2.2.1 g-C 3 N 4 /Fe 2 O 3 Heterojunction Photocatalyst
for Removal of Recalcitrant Pollutants
Among the countless properties exhibited by magnetic oxides, its large specific
surface area with ample number of reactive sites makes it available for anchoring
of pollutants. Additionally, its cost-effective nature and suitable bandgap of 2.2 eV
with regeneration ability exhibit more pronouncing effect for photodegradation of
pollutants. It is clearly apparent from review of literature that researchers have been
constantly exploiting the inherent properties of Fe 2 O 3 and g-C 3 N 4 photocatalyst for
water treatment purpose.
Babar et al. (2019) prepared g-C 3 N 4 /Fe 2 O 3 from waste toner powder
nanocomposite which exhibited 85% and 82% elimination of methyl orange dye
and textile effluents, respectively. X-ray diffraction studies confirmed that on
60
P. Raizada et al.