Synthesis and Application of the Ternary Zn_0.5Cd_0.5S/ZnO/carbon Xerogel Composite in the Photocatalytic Degradation of 4-chlorophenol

Abstract

The Zn_0.5Cd_0.5S/ZnO/carbon xerogel photocatalyst was synthesized through the thermal treatment of ZnO, CdS, and a low-cost carbon xerogel matrix at high temperature (600 ºC). ZnO is one of the most widely used photocatalysts, but it has low visible-light absorption, while Zn_0.5Cd_0.5S is a visible-light active photocatalyst, which can be used as a co-catalyst to enhance photoactivity under natural radiation and promote charge separation through the creation of Z-scheme heterojunctions. The further addition of the carbon xerogel can be justified by its highly developed porous structure and ability to capture photogenerated electrons, which will also promote charge separation. The creation of the hexagonal Zn_0.5Cd_0.5S and ZnO phases was confirmed through the X-ray diffractometry technique. The addition of the carbon xerogel led to an increase in the specific surface area of the XC/ZnO (630%) and XC/ZnO-Zn_0.5Cd_0.5S (320%) and a decrease in particle size when compared to the pure ZnO. Regarding the photocatalytic performance of the materials, the Zn_0.5Cd_0.5S/ZnO/carbon xerogel displayed an enhanced photocatalytic activity for 4-chlorophenol degradation, with 84% degradation after 300 minutes of artificial solar irradiation. The enhanced photoactivity of the Zn_0.5Cd_0.5S/ZnO/carbon xerogel composite was further confirmed by chronoamperometry, as the composite presented higher photocurrent generation under light irradiation.

Keywords:
Photocatalysis; carbon xerogel; zinc oxide; cadmium sulfide; Zn_0.5Cd_0.5S; 4-chlorophenol