Harnessing iron-rich biochar boosted single crystalline Co2VO4 nano-hexagons: A green photo-Fenton catalyst for rifampicin remediation and byproduct toxicity evaluation

A novel cation-substituted transition metal oxide nano-semiconductor was developed for efficient visible light photocatalysis. This nanocomposite (NCs) was created by immobilizing well-defined single crystalline Co2VO4 2D nano-hexagons onto a mesoporous biochar matrix, derived from philodendron plants. The Co2VO4 nanoparticles (NPs) were synthesized using a biologically assisted method employing an ornamental plant, L. delavayanum. Remarkably, the resultant NCs exhibited exceptional photocatalytic activity, achieving 99% degradation efficiency of pharmaceutical pollutant rifampicin (RIF), and merely 1.8% of total organic carbon (TOC) left as residues post-photocatalytic degradation. The influence of pH (optimal at 8), NCs and RIF concentration, and presence of ions was studied and the system worked effectively in a wide range of environment. The coupling of biochar resulted in a greater narrowing of the bandgap of Co2VO4 and thus extending the working range under visible light. A plausible mechanism assisted with photo-Fenton process is outlined based on the support of extensive characterization carried out to elucidate the NCs properties along with the results of scavenging experiments. The NCs performance retained over 98% efficiency even after six consecutive reusing cycles. The present study underscores the potential of the prepared NCs as a robust and effective solution for environmental pollutant removal, with its unique composition and synergistic photo-Fenton reaction contributing to its outstanding photocatalytic performance.