Innovative visualization of the effects of crystal morphology on semiconductor photocatalysts. Tuning the Hückel polarity of the shape-tailoring agents: the case of Bi 2 WO 6

• Published in: CrystEngComm 2019-02, Vol.21 (8), p.1267-1278
• Main Authors: Kása, Zsolt, Baia, Lucian, Magyari, Klára, Hernádi, Klára, Pap, Zsolt
• Format: Article
• Language: English
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/C8CE01744A

The shape-tailoring synthesis of different materials is a hot topic nowadays. The essence of morphology-controlling processes is to tune the geometry of the crystal in such a way that a desired property of the crystal can be preponderantly enhanced. However, the main issue of such synthesis approaches is to achieve simple morphological correlations with the applied shape-tailoring agents. This specific situation is also valid for shape-controlled photocatalytic materials. That is why in the present work Bi 2 WO 6 microcrystals were obtained using two shape-tailoring agents: Triton-X and amino acids/(tio)carbamide structures. The first of these agents was applied as a binary variable (presence or absence), while in the case of the second one, the Hückel polarity of the chalcogen–carbon double bond (CO or S) was considered as the changing parameter. The as-prepared materials were characterized by XRD, DRS, SEM and IR spectroscopy and their activity was verified under visible light illumination using rhodamine B as the model pollutant to enhance the general validity of the results. It was found that an empiric geometric function, defined as the “rose similarity decay constant” ( R SDC ), showed that a perfect rose shape (low R SDC ) or geometries with similarly low R SDC exhibited high photocatalytic activity. Moreover, the introduced empiric value was correlated with the Hückel polarity of the samples, thus showing for the first time a direct association between a structural parameter of the shape-tailoring agent, the obtained crystal geometry and the photoactivity.