Synergetic photocatalytic degradation of the tetracycline antibiotic over S-scheme based BiOBr/CuInS2/WO3 ternary heterojunction photocatalyst

Abstract

The present research investigated the photodegradation capability of a ternary BiOBr/CuInS₂/WO₃ heterojunction against the tetracycline (TC) antibiotic. BiOBr/CuInS₂/WO₃ heterojunction is formed using a straightforward physical mixing method, whereas pure photocatalysts (CuInS₂, WO₃) were synthesized hydrothermally and BiOBr by a coprecipitation process. The Field Emission Scanning Electron Spectroscopy examination validated the nanorod and nanosheet shape of the fabricated BiOBr-CuInS₂-WO₃. The photodegradation capabilities of the BiOBr-CuInS₂-WO₃ heterojunction were superior to those of other pure photocatalysts, and it followed the S-scheme charge transfer route as indicated by the band alignments. After 120 min of light irradiation, the BiOBr/CuInS₂/WO₃ S-scheme ternary heterojunction obtained a photodegradation rate of 98.9 %, much greater than other pure photocatalysts. According to electron spin resonance investigations and scavenging experiments, the radicals hydroxyl radicals (^•OH), hole (h⁺), superoxide (•O₂⁻) play a significant role in the photodegradation of TC. The ternary heterojunction's improved light absorption, lower recombination rate, and higher photocarrier separation rate were due to the fabrication of S-scheme heterojunction. The ternary BiOBr/CuInS₂/WO₃ photocatalyst's photodegradation efficacy was consequently enhanced. Investigations for photocatalyst reusability demonstrated its exceptional stability, with a 93.8 % degradation rate after five catalytic cycles.