Nanoscale ZnO/CdS heterostructures with engineered interfaces for high photocatalytic activity under solar radiation

Abstract

Semiconductor based nanoscale heterostructures are promising candidates for photocatalytic and photovoltaic applications with the sensitization of a wide bandgap semiconductor with a narrow bandgap material being the most viable strategy to maximize the utilization of the solar spectrum. Here, we present a simple wet chemical route to obtain nanoscale heterostructures of ZnO/CdS without using any molecular linker. Our method involves the nucleation of a Cd-precursor on ZnO nanorods with a subsequent sulfidation step leading to the formation of the ZnO/CdS nanoscale heterostructures. Excellent control over the loading of CdS and the microstructure is realized by merely changing the initial concentration of the sulfiding agent. We show that the heterostructures with the lowest CdS loading exhibit an exceptionally high activity for the degradation of methylene blue (MB) under solar irradiation conditions; microstructural and surface analysis reveals that the higher activity in this case is related to the dispersion of the CdS nanoparticles on the ZnO nanorod surface and to the higher concentration of surface hydroxyl species. Detailed analysis of the mechanism of formation of the nanoscale heterostructures reveals that it is possible to obtain deterministic control over the nature of the interfaces. Our synthesis method is general and applicable for other heterostructures where the interfaces need to be engineered for optimal properties. In particular, the absence of any molecular linker at the interface makes our method appealing for photovoltaic applications where faster rates of electron transfer at the heterojunctions are highly desirable.

Photocatalysis and Bandgap Engineering Using ZnO Nanocomposites

“…Our work is focused on the review of photocatalytic properties of composite nanostructures of ZnO with CdS [81,126,127,145,[148][149][150][151][152][153][154][155][156][157][158][159][160][161][162][163][164][165][166], TiO 2 [167][168][169][170][171][172][173][174][175][176][177], SnO [178], SnO 2 [179][180][181][182][183][184][185][186][187][188][189][190][191][192][193]…”

Ag/ZnO/graphene oxide heterostructure for the removal of rhodamine B by the synergistic adsorption–degradation effects

“…Thus the development of well-defined ZnO-based heterostructures with narrowed band gap, excellent light absorption and highly efficient dye adsorption has been actively pursued [13][14][15][16][17][18][19][20][21].…”

Aromatic compounds photodegradation catalyzed by ZnS and CdS nanoparticles

“…The photocatalytic activity of a Downloaded by [Dokuz Eylul University ] at 00:44 04 November 2014 semiconductor depends on surface and structural properties such as crystal composition, surface area, particle size distribution, porosity, band gap and surface hydroxyl density. The band-gap energies of ZnS and CdS semiconductors are 3.54 and 2.42 eV at 300 K, respectively [26,27]. Thus, the higher degradation efficiencies obtained at the presence of CdS with the lower band-gap energy.…”

“…This both prevents the electron from recombining with the hole and results in an accumulation of oxygen radical species that can also participate in attacking contaminants [27,28].…”