Photocatalysis can be an effective technique for eliminating organic contaminants from water. In this study, BiOBr flower-spheres coupled with porous graphite carbon nitride (g-C3N4) were synthesized by controlling the dosage of cetyltrimethylammonium bromide (CTAB). Various characterization techniques were then applied to elucidate the structure-performance relationships of the resulting heterojunction photocatalysts in degrading organic dyes. Experimental results established an optimal molar ratio for KBr to CTAB of 5:1. Benefiting from a remarkable porous structure and tight coupling between porous g-C3N4 and BiOBr, the optimal BiOBr-g-C3N4(2%) exhibited enhanced visible light absorption capability and promoted the separation of photoinduced carriers. Total removal efficiency for rhodamine B (RhB, 25.0 mL, 20.0 mg L-1) reached 87% within 30 min in the presence of BiOBr-g-C3N4(2%) (20.0 mg) (i.e., 1.51 μmol (gphotocatalyst min)-1), which is superior to the performance of BiOBr (72%) (i.e., 1.25 μmol (gphotocatalyst min)-1), g-C3N4 (21%) (i.e., 0.37 μmol (gphotocatalyst min)-1). Furthermore, the photocatalytic reaction rate constant over the optimal heterojunction was 0.034 min-1, which is significantly larger than those of porous g-C3N4 (0.003 min-1) and BiOBr (0.015 min-1). Moreover, this type II heterojunction showed good universality for other organic dyes (such as methyl violet, methylene blue, and crystal violet), highlighting a promising potential role in the elimination of environmental pollutants.
Keywords: BiOBr flower-Spheres; Organic dyes; Photocatalytic degradation; Porous g-C3N4; Type II heterojunction.
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