Investigation on cds quantum dots sensitized bismuth compounds for photocatalytic splitting of water and degradation of pollutants

Abstract

newline As a very promising method, solar light-driven water redox reaction is an efficient way newlineto solve energy crisis and solar energy induced degradation of pollutants is an effective newlinemode for resolving the disputes of environmental pollutions. Between H2 and O2 newlinegeneration, O2 evolution reaction is the difficult one because of consumption of four newlineelectrons and more potential required for H2O/O2 (1.23 eV vs. NHE). For this Bi-based newlinesemiconductors are best known for their water oxidation ability. However, their catalytic newlineactivity is retarded by some bottlenecks such as low charge separation and slow kinetics newlineof water oxidation reaction (WOR). Therefore, I have chosen CdS QDs to modify these newlinedrawbacks because of its size-dependent photoluminescence, high stability, narrow newlinebandgap, high dispersity, high absorption coefficient, ultra-small particle size, and newlinequantum confinement effect. The combination of CdS QDs and Bi-based semiconductors newlineare suitable for the water reduction reaction. Additionally, they equally contribute to newlineenvironmental remediation. The prepared composites are studied and analyzed newlinesystematically through structural, optical, compositional, morphological and newlineelectrochemical characterizations. Apart from these, the optical and fluorescence newlineproperty of CdS QDs were studied. newlineAtomically colloidal quantum dots are attractive for applications in far-reaching newlineoptoelectronic devices, due to fascinating physical properties. However, the relative low newlinephotoluminescence quantum yield (PLQY) of colloidal quantum dots was the main newlinebottleneck, due to abundant defects. For the first time, we are here suggesting a possible newlinesource of deviation from the reported work is solvent dependence PLQY of CdS QDs. newlineAs most visible light-emitting QDs, colloid CdS QDs prepared in four common solvents newlinelike water, ethanol, acetone and DMSO capped with thioglycolic acid (TGA) is taken newlineinto consideration here. Relative fluorescence quantum yield CdS QDs in DMSO is newlinefound to be highest i.e. 93 % among the solvents used. In addition to this Urbach energy newlinewas also calculated in order to have an idea about the density of states in CdS QDs. newlinevii newlineFigure