Nanoparticle Self-Assembled Grain Like Curcumin Conjugated ZnO: Curcumin Conjugation Enhances Removal of Perylene, Fluoranthene and Chrysene by ZnO

Abstract

Curcumin conjugated ZnO, referred as Zn(cur)O, nanostructures have been successfully synthesized, these sub-micro grain-like structures are actually self-assemblies of individual needle-shaped nanoparticles. The nanostructures as synthesized possess the wurtzite hexagonal crystal structure of ZnO and exhibit very good crystalline quality. FT-Raman and TGA analysis establish that Zn(cur)O is different from curcumin anchored ZnO (ZnO@cur), which is prepared by physically adsorbing curcumin on ZnO surfaces. Chemically Zn(cur)O is more stable than ZnO@cur. Diffuse reflectance spectroscopy indicates Zn(cur)O have more impurities compared to ZnO@cur. The solid-state photoluminescence of Zn(cur)O has been investigated, which demonstrates that increase of curcumin concentration in Zn(cur)O suppresses visible emission of ZnO prepared through the same method, this implies filling ZnO defects by curcumin. However, at excitation wavelength 425 nm the emission is dominated by fluorescence from curcumin. The study reveals that Zn(cur)O can remove to a far extent high concentrations of perylene, fluoranthene, and chrysene faster than ZnO. The removal depends on the extent of curcumin conjugation and is found to be faster for PAHs having smaller number of aromatic rings, particularly, it is exceptional for fluoranthene with 93% removal after 10 minutes in the present conditions. The high rate of removal is related to photo-degradation and a mechanism has been proposed.

Curcumin‐Functionalized Ag/Ag2O Nanocomposites: Efficient Visible‐Light Z‐scheme Photocatalysts

“…, is proposed. Curcumin has a HOMO–LUMO gap of 2.64 eV in the visible range . The HOMO of curcumin is at 0.55 eV and LUMO at −2.09 eV.…”

“…Here, Ag functions as the plasmonic component and on irradiation by light of appropriate frequency can concentrate the local electric field and boost it. As mentioned earlier, the semiconductor Ag 2 O has a narrow band (1.2-1.4 eV) gap and the HOMO-LUMO gap of curcumin is in the visible range (28). This study first presents the single-step green synthesis of Ag/Ag 2 O nanocomposite particles, with curcumin acting as the reducing as well as stabilizing agent.…”

“…9, is proposed. Curcumin has a HOMO-LUMO gap of 2.64 eV in the visible range (28 (1,23) are more positive than valence band edge of Ag/ Ag 2 O. On the other hand, the visible range LSPR of Ag helps in increasing photocatalytic efficiency by concentrating the visible-light irradiation and generating more efficiently electronhole pairs in the composite.…”

Photosensitive Hybrid Nanostructured Materials: The Big Challenges for Sunlight Capture

“…However, ZnO nanostructures resulted suitable for absorption in ultraviolet rather than visible light because of the wide bandgap (3.3 eV). Hybrid ZnO was synthesized with organic dye-sensitizers, such as 4-((2-hydroxynaphthalen-1-yl)diazenyl)benzoic acid (4ABBN), by precipitation or sol-gel route, for enhanced H 2 generation from water-methanol solution without co-catalysts [84], as well as curcumin by precipitation, for the degradation of polycyclic aromatic hydrocarbons in daylight conditions [82]. ZnO nanorods with adsorbed fluorescein, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), or protoporphyrin provided enhanced visible-light degradation of dyes and resorcinol [81].…”

Construction of a Visible Light Z‐scheme Photocatalyst: Curcumin Functionalized Cu2O/Ag Nanocomposites

“…Contrary to this, very little research has been reported in the fabrication of hybrids of wide bandgap semiconductors and organic molecules with visible range HOMO‐LUMO gap. Among various possibilities, the potential of curcumin for making such hybrids has been investigated by a few researchers, since the HOMO‐LUMO difference of curcumin is also in the visible light energy range . Thus, curcumin has been applied as an efficient photosensitizer in a dye‐sensitized solar cell .…”