From Adsorbent to Photocatalyst: The Sensitization Effect of SnO2 Surface towards Dye Photodecomposition

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.

Tunable Generation of Reactive Oxygen Species in SnO2/SnS2 Nanostructures: Mechanistic Insights into Indigo Carmine Photodegradation

“…the adsorption for RS with RS_1:1, represented by violet and green dashed lines in Figure a, respectively). The observed effect of pronounced NBT adsorption on the SnO 2 surface is consistent with our previous study, which revealed that the bare SnO 2 - and SnS 2 -coated samples exhibit different adsorption properties. It turned out that the RS sample more favorably adsorbs cationic dyes, such as rhodamine B (NBT is also a cationic dye).…”

“…Based on the conducted experiments, IC was chosen as a representative model dye for photocatalytic tests. These tests showed that increasing SnS 2 content in the samples improves the photodegradation rate of IC (Figure ).…”

“…In the case of RS (SnO 2 ), no quenching tests were performed as its photocatalytic activity in the IC degradation was very low (less than 10% efficiency using UV lampssee Figure S3 in the Supporting Information). According to our previous study, this sample exhibits a negative surface charge in the IC solution. Thus, anionic IC molecules are not readily adsorbed on the surface of SnO 2 .…”

Synthesis, properties and catalytic performance of the novel, pseudo-spinel, multicomponent transition-metal selenides

“…Historically, TMCh were associated mainly with thermoelectric applications and are still considered to be the benchmark for other materials, displaying performance beyond the capabilities of other materials groups. [1][2][3][4][5][6][7][8][9][10] However, recently, they have gained a lot of interest with regard to the possibility of their utilization in a number of other technologies operating on the basis of electrocatalytic processes, including photochemistry, [11][12][13] sensors, 12,14,15 fuel cells, and catalysis. 12,16,17 This interest stems from their excellent catalytic activity with respect to some of the most fundamental catalytic reactions, namely hydrogen evolution reaction (HER), and the oxygen evolution reaction (OER).…”

Indigo Carmine in a Food Dye: Spectroscopic Characterization and Determining Its Micro-Concentration through the Clock Reaction

“…Due to the potential toxicity and harmful effects of indigo carmine on the ecosystem and biodiversity, its presence and concentration must be reliably determined. Different methods have been proposed to identify and quantify indigo carmine in wide-range samples, based mainly on UV/Vis spectrometry [ 14 , 15 , 16 , 17 , 18 ], electrochemical techniques [ 19 , 20 , 21 ], chromatography [ 22 , 23 , 24 ], FTIR spectroscopy [ 12 , 25 ], as well as advanced digital imaging techniques [ 26 , 27 ]. Understandably, all of these techniques have different sensitivity and accuracy of indigo carmine detection mainly depending on sample nature (to be more precise on its matrix).…”