A novel Cr2O3/Cr-doped g-C3N4 photocatalyst with a narrowed band gap for efficient photodegradation of tetracycline

Two significant strategies for enhancing photocatalyst performance are heterojunction construction and band gap modulation, but up until now, these methods have typically been treated separately. This work examines a strategy combining the heterojunction with a mid-gap state to prepare a novel Cr2O3 modified Cr-doped g-C3N4 photocatalyst for antibiotics degradation. According to the characterization results, the integration of Cr 3d orbital energy level into the original band gap of g-C3N4 results in the formation of Cr-doped g-C3N4, leading to a reduction in the band gap from 2.80 eV to 2.36 eV. Besides, the constructed Z-type heterojunction enhances the separation of photoinduced carriers. The degradation experiments of tetracycline proved the significant enhancement in the photocatalytic performance of the prepared catalyst. In addition, the degradation effect of the prepared catalyst on tetracycline in micro-polluted lake water was also investigated, revealing the applicability of the catalyst in the purification of natural water environments. [Display omitted] •A combination of heterojunctions and mid-gap status strategies.•The 3d orbits of Cr were successfully introduced into the band gap of g-C3N4.•The narrowing of the forbidden band width results in considerable visible light absorption.•The synthesized catalysts were used to degrade tetracycline in contaminated water sources.