In situ fabrication of Bi₄Ti₃O₁₂/BiOCl heterojunctions with shared atomic layer for simulated wastewater treatment

A Bi₄Ti₃O₁₂/BiOCl heterojunction with a coherent interface was constructed via a room-temperature ion-exchange process. • A Bi₄Ti₃O₁₂/BiOCl heterojunction with a coherent interface was constructed via a room-temperature ion-exchange process. • The photocatalyst exhibits excellent performance for the degradation of high-concentration, recalcitrant antibiotics. A strategy is reported for the in-situ fabrication of a Bi₄Ti₃O₁₂/BiOCl heterojunction with shared atomic layer through simple room-temperature ion-exchange on pure Bi₄Ti₃O₁₂. This strategic interfacial engineering, combined with a Type-II band alignment, the Aurivillius-type Bi₄Ti₃O₁₂ and BiOCl share the Bi₂O₂ 2+ layers at the interface, thereby dramatically accelerating the separation and migration of photo-generated carriers and ultimately significantly increasing the yield of photocatalytic reactive species. Consequently, the optimized composite photocatalyst exhibits exceptional performance in the degradation of high-concentration antibiotics. It achieves remarkable degradation efficiencies of 90.8% for sulfamethoxazole (20 ppm) within 120 min, 92% for tetracycline hydrochloride (40 ppm) and 78.6% ciprofloxacin (15 ppm) within just 30 min. Demonstrating superior photocatalytic performance compared to the previously reported analogous photocatalysts in recent years with respect to antibiotic degradation. Furthermore, the degradation efficiency of the as-prepared photocatalyst also demonstrates outstanding cycling stability, with a reduction of only 3.4% after 4 cycles. Therefore, this coherent Bi₄Ti₃O₁₂/BiOCl heterojunction photocatalyst exhibits immense potential for practical applications in environmental remediation.