Abstract
Semiconductor photocatalysis is considered one of the most promising technologies for water purification from toxic organic dyes. However, to reliably evaluate the possibility of using a given material as a photocatalyst, it is crucial to investigate not only the photocatalytic activity but also its affinity towards various dyes and reusability. In this work, we studied the adsorptive/photocatalytic properties of hollow-spherical raspberry-like SnO2 and its SnO2/SnS2 heterostructures that were obtained via a chemical conversion method using three different concentrations of a sulfide precursor (thioacetamide). The adsorptive/photocatalytic properties of the samples towards cationic rhodamine B (RhB) and anionic indigo carmine (IC) were analyzed using uncommon wall zeta potential measurements, hydrodynamic diameter studies, and adsorption/photodecomposition tests. Moreover, after conducting cyclic experiments, we investigated the (micro)structural changes of the reused photocatalysts by scanning electron microscopy and Fourier-transform infrared spectroscopy. The obtained results revealed that the sensitization of SnO2 resulted not only in the significantly enhanced photocatalytic performance of the heterostructures, but also completely changed their affinity towards dyes. Furthermore, despite the seemingly best photocatalytic performance, the sample with the highest SnS2 content was unstable due to its (micro)structure. This work demonstrates that dye adsorption/desorption processes may overlap the results of cyclic photodecomposition kinetics.
Highlights
With rapidly growing industrialization and urbanization, water contamination is becoming an increasing problem worldwide [1]
The results revealed that SnO2 and its heterostructures are characterized by completely different affinities towards rhodamine B (RhB) and indigo carmine (IC)
The SnO2/SnS2 heterostructures were obtained via chemical conversion of hollow-spherical raspberry-like SnO2 nanomaterials (HS)
Summary
With rapidly growing industrialization and urbanization, water contamination is becoming an increasing problem worldwide [1]. The problem of dye-contaminated water has been addressed using various methods, such as biological treatment, membrane filtration, sorption processes, ion exchange, coagulation-flocculation, and catalytic oxidation [2,4,5]. Many of these methods do not decompose dyes, but only transfer them to other media, creating secondary pollution that needs post-treatment [4,5,6]. Semiconductor photocatalysis, as a green and sustainable technology, has attracted a lot of attention in recent years [5,6] In this process, organic dyes can be decomposed into non-toxic compounds (CO2 and H2O) under solar radiation and ambient conditions [4]
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