Photocatalytic reduction of o-chloronitrobenzene under visible light irradiation over CdS quantum dot sensitized TiO₂

Abstract

The photocatalytic activity of CdS/P25 hybrid catalysts was studied under visible-light irradiation. The CdS quantum dots sensitized P25 (CdS QDs-P25) showed extremely enhanced activity in the reduction of o-chloronitrobenzene (o-CNB) by comparing to CdS-P25 prepared by the direct deposition-precipitation method in the presence of HCOOH. The synergistic effects between CdS QDs and P25 were beneficial for the separation of photogenerated carriers in space and thus the combination of photoelectrons and holes was prevented, and the CdS QDs could provide more photocharges than CdS due to the particle size effect. Furthermore, the process of photocatalytic reduction in the present system was investigated, under visible-light irradiation, the photogenerated electrons transferred from the valence band (VB) to the conduction band (CB) of CdS QDs, and injected into the CB of inactivated P25. Meanwhile, the holes generated in the VB of CdS QDs could oxidize HCOO(-) to give ˙CO2(-) and H(+). Then, o-CNB was reduced to o-chloroaniline (o-CAN) by the couple of e(-) and ˙CO2(-) with H(+). It is a significant method and a green process for hydrogenation of nitro compounds, which may have great potential applications in the reduction of various organic chemicals.

Supercritical CO2 synthesized TiO2 nanowires covalently linked with core–shell CdS–ZnS quantum dots: enhanced photocatalysis and stability

“…10. 58 The electrons (e À ) accumulated at the CB of TiO 2 are scavenged by dissolved oxygen molecules in water to yield superoxide radial anions (O 2 À c) (eqn (4)), yielding hydroperoxy radicals HO 2 c on protonation (eqn (6)), and nally hydroxyl radicals OHc (eqn (7)). Due to the position of the conduction band (CB) and valence band (VB) of both QDs, the optimal CB and VB edges are located in the core CdS QDs.…”

Facile synthesis of CdS nanorods with enhanced photocatalytic activity

“…Therefore, many methods have been used to prepare CdS nanostructures with excellent photocatalytic activity, such as hydrothermal, solvothermal, sonochemical and precipitation method [9][10][11][12]. However, those methods usually come down to rigor requirements, such as complicated equipments, high power consumption and so forth [13][14][15][16][17].…”

Synthesis of PbS/Ni 2+ doped CdS quantum dots cosensitized solar cells: Enhanced power conversion efficiency and durability

“…However, the low separation efficiency of photogenerated electron-hole pairs and the fact that it is easily corroded are not favorable for the wide applications of CdS in semiconductor solar cells [24][25]. Therefore, it is highly desirable to develop highly efficient and corrosion resistant sensitizer based on the conventional semiconductor materials.…”