Unveiling the Mechanistic Aspects of Solar-Driven Hematein Remediation Using Biocompatible Metal-Free Carbon Nitride Nanosheets

Hematein, the oxidized form of hematoxylin, is extensively used in laboratories for cell identification. Despite its known adverse effects on the environment, there is currently no standardized method for hematein treatment. With the objective of developing a simplified approach for hematein degradation at the point of use, we evaluated the photocatalytic performance of the as-prepared polymeric graphitic carbon nitride (C₃N₄). The formation of exfoliated C₃N₄ (E-C₃N₄₎ was confirmed through the observation of reduced sheet thickness, increased surface area, and a modified band gap. E-C₃N₄ exhibited a higher degradation rate compared to bulk C₃N₄ under solar irradiation owing to the lower charge transfer resistance and improved charge separation. Transient absorption spectroscopy revealed that the hot electrons of E-C₃N₄ readily transfer to the photoactive sites and efficiently facilitate hematein degradation. Additionally, we also noted the degradation of hematein occurring through an exciton-mediated energy transfer pathway. The catalytic performance appeared to improve with an increase in the catalyst concentration. Notably, E-C₃N₄ demonstrated consistent degradation performance over five cycles. Our results confirm that hematein can be repeatedly degraded in the laboratory using the biocompatible E-C₃N₄, and the byproducts generated during hematein degradation were found to be biocompatible. This study represents a step toward developing an environmentally friendly and efficient method for hematein treatment in laboratory settings.