Microwave-Assisted Synthesis of BiOI for Solar-Driven Environmental Remediation

Bismuth oxyiodide (BiOI) microspheres were synthesized by a microwave-assisted solvothermal method at 126 °C in only 4 min, a significantly shorter reaction time than in previously reported works. The structural, surface, morphological, and optical properties of BiOI were analyzed and correlated with the photocatalytic activity during the degradation of gallic acid (GA) and the photo-oxidation of nitric oxide (NO) in the aqueous and gas phases, respectively. The BiOI microspheres exhibited higher first-order apparent rate constants for GA and NO (0.188 min−1 and 0.230 min−1) than the benchmark TiO2 P25 (0.101 min−1 and 0.066 min−1). In addition, in steady-state reaction conditions (after 10 min), BiOI achieved 86% degradation of GA instead of the 63% degradation observed with TiO2 P25. Furthermore, at the same point in the reaction, the BiOI microspheres showed up to 65% NO conversion, while TiO2 P25 only achieved 15%. Accordingly, the results suggest that the microwave-assisted solvothermal method provides significant advantages for rapid, low-cost, and eco-friendly synthesis of BiOI microspheres for photocatalytic remediation of polluted water and air.