Synthesis of the novel (BiO)4CO3(OH)2/BiOBr heterostructure with enhanced photocatalytic reduction of Cr(vi) and degradation of tetracycline

Abstract

The (BiO)₄CO₃(OH)₂/BiOBr heterojunction was developed by a facile hydrothermal process using polyhedral (BiO)₄CO₃(OH)₂ as the precursor and HBr as the etching agent. BiOBr nanosheets were vertically and orderly grown on the surface of (BiO)₄CO₃(OH)₂, and the obtained (BiO)₄CO₃(OH)₂/BiOBr heterojunction exhibits outstanding photocatalytic performance to degrade 50 mg L⁻¹ of Cr(VI) and 30 mg L⁻¹ of TC in 25 and 20 min, respectively, under simulated sunlight. The enhanced photocatalytic performance is the synergistic effect of the two factors: the unique hierarchical structure can effectively utilize light, and the suitable position of the band edge is conducive to the construction of a Z-scheme heterostructure. The free radical capture confirms that superoxide free radicals (˙O₂⁻) and hydroxyl radicals (˙OH) are the major active agents during photocatalysis. Based on the transient photocurrent response and electrochemical impedance measurements, the (BiO)₄CO₃(OH)₂/BiOBr heterostructure shows excellent separation efficiency of the photogenerated electron–hole pairs. This finding will inspire many researchers to develop novel high-performance photocatalysts for degrading harmful and toxic pollutants and remediating environmental pollution.