Facile Stitching of Boron-Doped Polymeric Carbon Nitride with Graphene-Based Nanosheets into a Self-Supporting and Recoverable Photocatalyst for Efficient Antibiotic Removal from Wastewater

Polymeric carbon nitride (CN) holds tremendous promise as a visible light-active photocatalyst. However, its widespread application is hindered by low light harvesting efficiency and its powdery nature. This study addresses these limitations by doping CN nanosheets with boron (B). Specifically, a series of B-doped CN (BCN) samples with varying dopant contents were developed and evaluated for their effectiveness in degrading sulfamethoxazole (SMX). The most effective BCN variant was then hydrothermally integrated with graphene oxide nanosheets to create a BCN/graphene aerogel (BCN/GA). A key objective of this effort was to overcome challenges associated with the separation and recovery of BCN sheets from the aqueous phase after treatment. The free-standing composite aerogel exhibited improved charge carrier separation and superior light absorption capacity compared with BCN, which can be attributed to its interconnected porous morphology and high buoyancy. Notably, a maximum SMX degradation of 93% was achieved under visible light within 120 min. Additionally, extensive environmental safety assessments of the degradation byproducts, conducted using ECOSAR software, along with seed germination tests on Vigna radiata, confirmed the ecological compatibility of the treated SMX solution. Furthermore, BCN/GA can be easily recovered post-treatment and demonstrates excellent reusability, showing great potential for large-scale photocatalytic wastewater treatment applications.