Abstract
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•Mesoporous CoFe2O4/g-C3N4 were synthesized using templates approach.•Hg(II) photoreduction in presence of formic acid as holes sacrificial was carried out.•For the first time, the synthesized samples exhibited large surface areas (115 m2 g−1).•4% CoFe2O4/g-C3N4 was achieved a high Hg(II) photoreduction rate of 539.91 μmolg−1 h−1.•Hg(II) photoreduction rate is 11.5 and 7.8 times magnitudes than g-C3N4 and CoFe2O4.
In this contribution, synthesis of mesoporous CoFe2O4/g-C3N4 heterostructures employing soft and hard templates approaches was explored to produce large surface area (151 m2 g−1) and tight bandgap (2.05 eV) photocatalysts for Hg(II) photoreduction under visible light illumination. TEM image exhibited that CoFe2O4 NPs are well distributed over g-C3N4 nanosheet with a spherical like structure ∼ 5−10 nm. The magnetization values for CoFe2O4 NPs and 4%CoFe2O4/g-C3N4 heterostructure were calculated ∼ 6.21 and 11.07 emu g–1, which are very high values compared to the published papers. Mesoporous CoFe2O4/g-C3N4 exhibited a greater photocatalytic efficiency than pure either CoFe2O4 NPs or g-C3N4. Hg(II) photoreduction efficiency boosted from 16.2 % to 100 % as the CoFe2O4 NPs contents increased from 0 to 4% in the mesoporous CoFe2O4/g-C3N4 heterostructures within 60 min. The Hg(II) photoreduction rate goes more quickly over mesoporous 4%CoFe2O4/g-C3N4 (539.91 μmolg−1 h−1) as compared to pure either g-C3N4 (79.86 μmolg−1 h−1) and CoFe2O4 NPs (117.25 μmolg−1 h−1). The key factor for promoting Hg(II) photoreduction is the highly dispersed CoFe2O4 NPs onto the surface of g-C3N4 and their large surface area, narrow bandgap, small particles size, harvest light and high diffusion of Hg(II) into the pores. Mesoporous CoFe2O4/g-C3N4 are magnetically removable easily possessing a high recyclability and durability in the Hg(II) photoreduction in aqueous solutions.