Rod-Shaped Carbon Aerogel-Assisted CdS Nanocomposite for the Removal of Methylene Blue Dye and Colorless Phenol

Abstract

A carbon aerogel (CA)-assisted CdS nanocomposite was prepared by hydrothermal process and was investigated as a photocatalyst towards the photodegradation of methylene blue (MB) dye and colorless phenol under visible light irradiation (VLI). CdS have attracted wide attention due to their relatively narrow band gap for the visible light effect and the suitably negative potential of the conduction band (CB) edge for the neutralization of H+ ions. The obtained characterization results suggest that the CA-assisted CdS nanocomposite has enhanced photophysical properties, a more surface area, and the desired morphology at the nm scale. Under optimization, CdS CA 8% shows superior catalytic activity for degradation compared with other samples. The photocatalytic activities of the as-synthesized samples were examined under VLI through the MB and phenol degradation. Compared with pure CA and CdS, the CA (8%)-assisted CdS nanoparticles (NPs) offer significantly enhanced photocatalytic efficiency for MB and phenol. The mechanism of photocatalytic reaction was examined by adding various scavengers, and the results revealed that the holes generated in CA (8%)-assisted CdS NPs have a crucial impact on the visible light photocatalytic process. The improved photocatalytic degradation was due to the strong interaction between the CA and CdS NPs.

Optical properties and photoactivity of carbon nanodots synthesized from olive solid wastes at different carbonization temperatures

“…The high degradation efficiency and the rate at 300 °C are ascribed to a wide bandgap compared to the other synthesized CNDs, because an increase in bandgap energy in the visible region from 2.46 to 2.77 eV can increase the separation of holes (h + ) and electrons (e − ) and hinder and delay the rapid recombination process of charge carriers h + and e − . 90 …”

“…and electrons (e À ) and hinder and delay the rapid recombination process of charge carriers h + and e À . 90 When high-energy photons excite the CNDs, electrons are excited from the ground state (valence band) to the excitation state (conduction band), resulting in excess electrons (e À ) and holes (h + ). Because of the abundance of surface defects on the CNDs, some excited carriers are trapped, preventing e À and h + recombination.…”

“…The degradation rate is gradually decreased when the carbonization temperature increases, decreasing by 3.25 fold when the temperature is raised from 300 to 600 C. The high degradation efficiency and the rate at 300 C are ascribed to a wide bandgap compared to the other synthesized CNDs, because an increase in bandgap energy in the visible region from 2.46 to 2.77 eV can increase the separation of holes (h + ) and electrons (e À ) and hinder and delay the rapid recombination process of charge carriers h + and e À . 90 When high-energy photons excite the CNDs, electrons are excited from the ground state (valence band) to the excitation state (conduction band), resulting in excess electrons (e À ) and holes (h + ). Because of the abundance of surface defects on the CNDs, some excited carriers are trapped, preventing e À and h + recombination.…”

Green synthesis of fluorescent carbon nanodots from sage leaves for selective anticancer activity on 2D liver cancer cells and 3D multicellular tumor spheroids

“…And part of the h + may combine with surface-adsorbed H 2 O to produce hydroxyl radicals, while the e − may be captured by oxygen dissolved in the solution, producing superoxide radicals. 82 …”

“…Several excited carriers are trapped on the CNDs because of the many surface aws inhibiting e − and h + recombination. And part of the h + may combine with surface-adsorbed H 2 O to produce hydroxyl radicals, while the e − may be captured by oxygen dissolved in the solution, producing superoxide radicals 82.…”