Surface construction of a novel metal-free g-C3N4-based heterojunction photocatalyst for the efficient removal of bio-toxic antibiotic residues

Abstract The exploration of metal-free g-C3N4-based photocatalysts is recognized as one of the most effective approaches for remedying environmental pollution and ameliorating energy crisis. However, the simultaneous realization of a highly efficient, long-term stability and broad visible-light responsive photocatalysts remains a major desirable challenging goal in the area of photocatalysis. Herein, using N,N′-bis(p-carboxyl-phenylene) perylene-3,4:9,10-perylene bisimide (BCPP-PBI) as the efficient surface photovoltaic agent, a novel BCPP-PBI/g-C3N4 heterojunction is successfully constructed via an one-step acylation reaction for the first time. The optimized 1%BCPP-PBI/g-C3N4 composite exhibited significantly improved visible-light absorption capability for light with wavelength shorter than 658 nm and demonstrated remarkably enhanced photocatalytic performance in tetracycline degradation with high stability. Benefitting from the surface modification effect by incorporating BCPP-PBI onto g-C3N4, there is a significantly improved visible light harvesting capability, as well as, a highly efficient photoexcited charges carrier separation and transfer system in 1%BCPP-PBI/g-C3N4. The strong covalent chemical bond formed between BCPP-PBI and g-C3N4 enabled the BCPP-PBI molecules to serve as important electron sink which adopts electrons from g-C3N4. This study paves the way for the design of highly effective g-C3N4-based metal-free organic catalysts towards their practical utilization in the elimination of recalcitrant antibiotic pollutants from various real wastewaters.