Engineering defects and lattice disorientation in layered double hydroxides by coupling 2D-Co(OH)2 platelets via p-n heterojunction for enhanced photocatalytic degradation chloramphenicol

Abstract

Defects and interface engineering play pivotal roles in optimizing the photocatalytic performance of heterojunctions. Among these, layered double hydroxides (LDH) stand out due to their two-dimensional lamellar structure and optical properties. This study focuses on creating a heterojunction between 2D-Co(OH)₂ platelets and defect-induced 2D-MgFe LDH by constructing interfacial electric field via p-n junction and enhanced the photocatalytic degradation of chloramphenicol. HR-TEM analysis shows abundant vacancies and lattice disorientation, affirming the effectiveness of defect engineering. The MgFe LDH–Co(OH)₂ nanocomposite (NCs) was synthesized through a straightforward co-precipitation and ultrasonic method. The band gap of 2.05 eV for MgFe LDH–Co(OH)₂ facilitated visible light absorption, leading to a remarkable 95.9 % degradation of chloramphenicol within 180 min under optimal conditions. The comparison studies conducted with layered double oxides (LDO) showed its lower efficacy than LDH. The stability of the NCs over five cycles and magnetic nature showcased their potential for large-scale wastewater treatment applications. Furthermore, both hydroxyl radicals (•OH) and superoxide radicals (O₂•⁻) were generated by the photocatalysis, as well as through the assistance of the Fenton reaction. The intermediates detected by GC-MS was tested for its toxicity using ECOSAR program which indicates its ideal for safe practical applications. This comprehensive study highlights the importance of defect engineering and heterojunction design in advancing photocatalytic materials for environmental remediation and paves a way for manufacturing innovation.