Facile construction of Z-scheme g-C3N4/BiOI heterojunction for improving degradation of tetracycline antibiotics

•Self-assembled tubular g-C3N4 was synthesized via a facile thermal treatment.•g-C3N4 nanotubes were coupled with BiOI microspheres to form Z-scheme heterojunction.•5 wt%-g-C3N4/BiOI heterojunction exhibited the highest TC removal efficiency. Tubular g-C3N4 derived from melamine and trithiocyanuric acid was coupled with flower-like BiOI microspheres to form Z-scheme heterojunction photocatalyst for the efficient photocatalytic degradation of tetracycline (TC). The structure, morphology, and optical properties of the prepared g-C3N4/BiOI were characterized. When the mass fractions of g-C3N4 in the composites was 5 wt%, g-C3N4/BiOI exhibited the highest removal efficiency of 84.2 % within 60 min. The enhanced photocatalytic performance of g-C3N4/BiOI could be ascribed to stronger absorption in the visible region and faster charge transfer rate. Trapping experiments revealed that h+ and ·O2− radicals were the main active species. Based on the band structure and trapping experiments, the Z-scheme pathway was proposed to clarify the photocatalytic mechanism.