Controlled hydrothermal synthesis of bismuth oxychloride/bismuth oxybromide/bismuth oxyiodide composites exhibiting visible-light photocatalytic degradation of 2-hydroxybenzoic acid and crystal violet

Ciao-Wei Siao; Hung-Lin Chen; Li-Wen Chen; Jia-Lin Chang; Tsung-Wen Yeh; Chiing-Chang Chen

doi:10.1016/j.jcis.2018.04.097

Controlled hydrothermal synthesis of bismuth oxychloride/bismuth oxybromide/bismuth oxyiodide composites exhibiting visible-light photocatalytic degradation of 2-hydroxybenzoic acid and crystal violet

J Colloid Interface Sci. 2018 Sep 15:526:322-336. doi: 10.1016/j.jcis.2018.04.097. Epub 2018 Apr 26.

Authors

Ciao-Wei Siao¹, Hung-Lin Chen², Li-Wen Chen¹, Jia-Lin Chang¹, Tsung-Wen Yeh¹, Chiing-Chang Chen³

Affiliations

¹ Department of Science Education and Application, National Taichung University of Education, 403, Taiwan.
² Department of Chemistry, National Central University, Taoyuan 320, Taiwan.
³ Department of Science Education and Application, National Taichung University of Education, 403, Taiwan. Electronic address: ccchen@mail.ntcu.edu.tw.

PMID: 29751266
DOI: 10.1016/j.jcis.2018.04.097

Abstract

This paper presents an unprecedented systematic synthetic study of a controlled hydrothermal method for the preparation of bismuth oxychloride/bismuth oxybromide/bismuth oxyiodide ternary composites (BiO_xCl_y/BiO_mBr_n/BiO_pI_q). The pH, temperature, and KCl:KBr:KI molar ratio for the reactions were adjusted to control the compositions and morphologies of BiO_xCl_y/BiO_mBr_n/BiO_pI_q composites. Scanning electron microscopy-energy dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, Brunauer-Emmett-Teller specific surface areas, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy, and electron paramagnetic resonance spectroscopy were applied to the products. The photocatalytic activities of dispersions were examined by monitoring the 2-hydroxybenzoic acid (HBA) and crystal violet concentrations. Various scavengers demonstrated quenching effects. O₂^- was crucial to HBA degradation, whereas h⁺ and OH played minor roles in HBA degradation. This text hypothesizes possible photodegradation mechanisms.

Keywords: 2-Hydroxybenzoic acid; BiO(x)Cl(y)/BiO(m)Br(n)/BiO(p)I(q); Composites; Crystal violet; Photocatalysis.