Enhanced Photocatalytic Performance of a ZnO/CdS Heterostructure for Hydrogen Production and Mixed Dye Degradation

Abstract

ZnO/CdS composite was prepared using a simple one‐step hydrothermal method, and its photocatalytic performance was investigated under different conditions. The photocatalytic efficiency of ZnO/CdS was 6345.04 μmol ⋅ g−1 ⋅ h−1 in H2 production from water splitting using Na2S and Na2SO3 as sacrificial agents. The photocatalytic efficiency of eosin Y‐sensitized ZnO/CdS was 6939.39 μmol ⋅ g−1 ⋅ h−1 when triethanolamine was used as a sacrificial agent. The photocatalytic activity of ZnO/CdS was better than those of pristine ZnO and CdS during H2 evolution. The ZnO/CdS composite also exhibited superior photocatalytic activity compared to pristine ZnO and CdS in the degradation of a mixed dye pollutant. The degradation rates of methylene blue, rhodamine B, and orange G in the mixed dye after 120 min of irradiation were 99.41 %, 92.96 %, and 65.74 %, respectively. Possible mechanisms for photocatalytic H2 production and photocatalytic degradation of organic pollutants have been proposed.

Ce‐Doped MoO3 Photocatalyst as an Environmental Purifier for Removal of Noxious Rhodamine B Organic Pollutant in Wastewater

“…Herein, X is the pure electronegativity of the semiconductor, E H is the hydrogen-scale energy of free electrons (%4.5 eV), E CB shows the energy of conduction band, E g is the energy of the bandgap, and E VB represents the valance band potential. [64] The X value for MoO 3 is 6.4 eV, as reported earlier [65] The estimated position potentials for valance band and conduction value of 2-CMO are 3.16 and 0.64 eV, respectively. The model proposed for photocatalytic reduction of rhodamine B dye by Ce-doped MoO 3 in the presence of visible light is depicted in the Figure 8.…”

Effect of CdS on microstructure and performance of ZnO composite photocatalyst

“…Among them, CdS is a common visible light-responsive photocatalyst. According to literature reports, 20,21 the lattice structure of CdS is similar to ZnO, if ZnO and CdS are effectively combined, the two can form close contact heterojunction, which can reduce the probability of electron-hole pair recombination, thereby improving the catalytic performance. In the CdS/ZnO composite, since the conduction band (CB) position of CdS is higher than that of ZnO, the free electrons in CdS spontaneously diffuse into ZnO until their Fermi levels reach equilibrium.…”

Flower‐Like Ag6Si2O7/Bi12O17Cl2 p‐n Heterojunctions: Enhanced Photocatalytic Activity and Mechanistic Insight**

“…Hence, it is an urgent and significant task to explore and develop efficient, low‐cost and environmentally friendly technologies to completely remove RhB from the water environment. Therefore, researchers have tried to use a variety of chemical, physical and biological methods to remove RhB from wastewater in recent years [3] . Among them, the photocatalytic oxidation method has attracted widespread attention because of its outstanding advantages such as mild reaction conditions, small secondary pollution, high efficiency and high reusability performance [4,5] …”

“…Therefore, researchers have tried to use a variety of chemical, physical and biological methods to remove RhB from wastewater in recent years. [3] Among them, the photocatalytic oxidation method has attracted widespread attention because of its outstanding advantages such as mild reaction conditions, small secondary pollution, high efficiency and high reusability performance. [4,5] BiOX (X = Cl, Br, I) materials have generated considerable interest in the direction of photocatalysis attributed to their excellent chemical stability, characteristic band structure and multiple morphologies.…”