Optimized Hydrothermal Synthesis of Highly Crystalline Sheet-Like BiOCl Powders for Enhanced Photocatalytic Degradation of Organic Pollutants

Bismuth oxychloride (BiOCl) powders, known for their layered structure and photocatalytic properties, were synthesized via an optimized hydrothermal method to improve environmental remediation efficiency. The synthesis involved reacting bismuth nitrate and sodium chloride in an aqueous solution, followed by hydrothermal treatment at 100 °C or 200 °C for varying durations (2, 4, and 6 h), and subsequent drying of the precipitated BiOCl powders. Structural and morphological properties were investigated using XRD, SEM, BET, EDS, FTIR, and UV–DRS. BiOCl synthesized at 200 °C for 4 h (BiOCl-200-4) showed the highest crystallinity and sheet-like morphology, enhancing charge separation and light absorption. BiOCl-200-4 demonstrated excellent photocatalytic activity under UV light, achieving 99.90% degradation of methyl orange (MO) with a rate constant of 0.0290 min⁻¹ under optimal conditions (2.5 mg/L MO, 0.6 g/L catalyst dosage, pH 3). Scavenger tests confirmed photogenerated holes and hydroxyl radicals as primary reactive species. BiOCl-200-4 also retained 90.28% of its activity after five cycles, indicating good stability. Unlike previous studies, this work systematically optimizes synthesis parameters to control crystallinity, morphology, and facet exposure, achieving a dominant (001) orientation that improves photocatalytic efficiency. The study also demonstrates a high-yield (94.73%) and scalable synthesis route, offering practical advantages over conventional approaches. These findings provide new insights into structure–function relationships and position BiOCl as a promising, sustainable photocatalyst for wastewater treatment.

Graphical Abstract