Bismuth-rich oxyhalide (Bi7O9I3-Bi4O5Br2) solid-solution photocatalysts for the degradation of phenolic compounds under visible light

Auttaphon Chachvalvutikul; Tawanwit Luangwanta; Burapat Inceesungvorn; Sulawan Kaowphong

doi:10.1016/j.jcis.2023.03.063

Bismuth-rich oxyhalide (Bi₇O₉I₃-Bi₄O₅Br₂) solid-solution photocatalysts for the degradation of phenolic compounds under visible light

J Colloid Interface Sci. 2023 Jul:641:595-609. doi: 10.1016/j.jcis.2023.03.063. Epub 2023 Mar 14.

Authors

Auttaphon Chachvalvutikul¹, Tawanwit Luangwanta¹, Burapat Inceesungvorn², Sulawan Kaowphong³

Affiliations

¹ Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
² Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence in Materials Science and Technology, Chiang Mai University, Chiang Mai 50200, Thailand; Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
³ Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence in Materials Science and Technology, Chiang Mai University, Chiang Mai 50200, Thailand; Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand. Electronic address: sulawank@gmail.com.

PMID: 36963253
DOI: 10.1016/j.jcis.2023.03.063

Abstract

Hypothesis: The development of solid-solution photocatalysts with tunable bandgaps and band structures, which are significant factors that influence their photocatalytic properties, is crucial.

Experiments: We fabricated a series of novel bismuth-rich Bi₇O₉I₃-Bi₄O₅Br₂ solid-solution photocatalysts with controlled I:Br molar ratios (denoted as B-I_xBr_1-_x, x = 0.2, 0.3, 0.4, or 0.6) via a rapid, facile, and energy-efficient microwave-heating route. The photodegradations under visible-light irradiation of the phenolic compounds (4-nitrophenol (4NP), 3-nitrophenol (3NP), and bisphenol A (BPA)), and the simultaneous photodegradation of BPA and rhodamine B (RhB) in a coexisting BPA - RhB system were investigated.

Findings: The B-I_0.3Br_0.7 solid solution provided the highest photocatalytic activity toward 4NP degradation, with degradation rates 32 and 4 times higher than those of Bi₇O₉I₃ and Bi₄O₅Br₂, respectively. The photodegradation efficiency of the studied phenolic compounds followed the order BPA (97.5%) > 4NP (72.8%) > 3NP (27.5%). The RhB-sensitization mechanism significantly enhanced the photodegradation efficiency of BPA. Electrochemical measurements demonstrated the efficient separation and migration of charge carriers in the B-I_0.3Br_0.7 solid solution, which enhanced the photocatalytic activity. The B-I_0.3Br_0.7 solid solution effectively activated molecular oxygen to produce •O₂^-, which subsequently produced other reactive species, including H₂O₂ and •OH, as revealed by reactive-species trapping, nitroblue tetrazolium transformation, and o-tolidine oxidation experiments.

Keywords: Bismuth-rich oxyhalide; Dye-sensitization; Microwave synthesis; Phenolic compounds; Photodegradation; Solid solution.