Читать книгу Functionalized Nanomaterials for Catalytic Application - Группа авторов - Страница 23

Recently, conjugation of C and N in a metal-free graphitic polymer is a hotspot that captivates the research workers to utilize the visible energy for the receptive photocatalytic zone in redemption of water pollutants [149]. Normally, hetero-junctions of g-C₃N₄–based PC are obtained by fusing g-C₃N₄ (semiconductor) PC and a co-catalyst (semiconductor). Significantly, type II hetero-junction and Z-scheme PC are predominantly employed by many co-workers for removing OPs. Z-scheme have been extensively utilized in BiOI/Pt/g-C₃N₄ [150], MoO₃/g-C₃N₄ [151], g-C₃N₄/FeWO₄ [152], g-C₃N₄/Ag/MoS₂ [153], TiO₂/g-C₃N₄ [154], and g-C₃N₄/Ag/Ag₃VO₄ [155]. While, straddling, staggered, and broken heterojunctions belonging to type 1, type 2, or type 3, with a small/large bandgap between CB and VB/or CB and VB with high potentials, are used in ZnO/g-C₃N₄ [156], Bi/Bi₂WO₆/g-C₃N₄ | Bi/Bi₂MoO₆/g-C₃N₄ [157], SmVO₄/g-C₃N₄ [158], g-C₃N₄/CuWO₄ [159], and BiVO₄/g-C₃N₄ [160]. Thus, many FNMs have been used in fabrication, to name a few for the removal of organic toxics like MB, MO, Rh B, fuchsin, and X3B form water segments.

Li, H. et al., fabricated WO₃/Cu/g-C₃N₄ nanohybrids to degrade 4-nonylphenol [161]. While, Yang, Y. et al. used Ag@AgBr/g-C₃N₄ FNMs as nano-composites to degrade MO [162]. Similarly, the authors Fu, J., et al., in their recent publication of CdS/g-C₃N₄, demonstrated a comparable output in enhancement-factor as 20.5 and 3.1 for dye-degradation of MO while using the composites of two active semiconductors g-C₃N₄ and CdS individually [163]. Later, in another experiment, the authors Yang, Y. et al. investigated SPR results of Ag NMs while studying the performance of Ag-coated-g-C₃N₄ over MO dye-degradation [164]. In another situation, researchers Ma, D. et al. revealed that g-C₃N₄/RGO/Bi₂WO₆ FNMs that fit the Z-scheme had RGO as a bridge to transfer the e⁻ electrons between the two bands g-C₃N₄ and Bi₂WO₆. The photoelectrons formed in the CB of the later Bi₂WO₆ moves rapidly into the VB of the former g-C₃N₄ (holes) to accumulate sufficient (e⁻) electrons in the CB of the former and holes of VB in the later. FNMs were found effective to photocatalytically degrade and remove TCP from water [165].

In a separate work, Jiang, Z. et al. engineered TiO₂/g-C₃N₄ by solvothermal method and proved its photocatalytic degrading properties over Rh B, MB, and CIP. H⁺ and superoxide ^·O²⁻ had significant role over ^·OH radical in this reaction. Excitonic PL signals indicated that n-π* electronic shifts were involved by lone pairs e⁻ present in N atoms of g-C₃N₄. Hetero yolk-shell structure formed significantly promoted the charge transference efficacy [166]. In a new protocol, facile magnetic g-C₃N₄/Fe₃O₄/p-Ru NP FNMs photo-nano catalyst got by deposition-precipitation process showed excellent degradation capacity and reusability with only 5% efficacy lost detected after five cycles. Photocatalysts degraded organic matters—aromatic amines and coloring pigments—azo dyes (CR, CB, EB, and RR-120) efficiently from industrial aqueous water. Formation of photo-electron creates h⁺ (holes), where the reactive ^·OH formed induces a responsible oxidative photo-degradation and h⁺ (holes)/^·O²⁻ radicals have insignificant roles [167].