In situ modification of bismuth oxyhalide photocatalysts with natural chlorophyll for enhanced photocatalytic performance

Abstract

Bismuth oxyhalides (BiOX) exhibit limited sunlight absorption and utilization, presenting a challenge for their effectiveness in photocatalytic applications. This study draws inspiration from the sensitization effects of natural chlorophyll on semiconductor photocatalysts, achieving in situ synthesis of chlorophyll-sensitized BiOX photocatalysts through a precipitation method. The photocatalytic activity of these materials was evaluated under blue light irradiation (410–420 nm LED) using Rhodamine B (RhB) as a model pollutant. Experimental results reveal that chlorophyll derived from Chlorella effectively sensitized BiOX samples, changed them specific surface area, and surface potential, thereby enhancing RhB degradation efficiency. Among the as-prepared BiOX materials, BiOBr demonstrated the most pronounced improvement, achieving a 97.8% degradation rate for 20 mg per L RhB within 90 min after sensitization. Mechanistic investigations through free radical trapping experiments identified superoxide radicals (˙O₂⁻), photogenerated electrons (e⁻) and holes (h⁺) as the key reactive species driving RhB degradation. This study underscores the critical role of chlorophyll sensitization in improving the photocatalytic efficiency of BiOX and provides a comparative analysis of the photocatalytic performance of BiOCl, BiOBr, and BiOI. The findings offer valuable perspectives for the advancement and practical implementation of sensitized photocatalysts in environmental remediation.