Metal–Organic Framework-Derived Hierarchical Ag/Sr<sub>6</sub>Bi<sub>2</sub>O<sub>9</sub>-α-Bi<sub>2</sub>O<sub>3</sub> Ternary Photocatalyst for Micropollutant Remediation and Bacterial Photoinactivation
Swagat Kumar Nayak, Priyanka Dash, Ranjit Bariki, Sibun Kumar Pradhan, Saumyaranjan Panda, Bismita Nayak, Braja Gopal Mishra
Abstract
High Resolution Image Download MS PowerPoint Slide In this work, a hierarchical Ag/Sr 6 Bi 2 O 9 -α-Bi 2 O 3 (Ag/SBO-BO) ternary heterostructure photocatalyst was fabricated by an MOF-derived route and studied for aqueous-phase micropollutant remediation and inactivation of water pathogens. The as-synthesized Ag/Sr 6 Bi 2 O 9 -α-Bi 2 O 3 composite inherited the cuboidal-rod shape morphology of the pristine Bi-MOF with an internal hollow structure. The Ag nanodots (3–5 nm) were preferentially decorated over the planar surface of high-aspect-ratio Sr 6 Bi 2 O 9 nanosheets, which were epitaxially grown over the porous Bi 2 O 3 (BO)-microrods. The Ag/SBO-BO composite displayed important structural attributes including anionic vacancies and formation of a tight heterojunction between Sr 6 Bi 2 O 9 /Bi 2 O 3 (SBO-BO) phases, which endowed superior optical absorption, synergistic charge channelization, and higher photoexcited state lifetimes. The improved optoelectronic features of Ag/Sr 6 Bi 2 O 9 -α-Bi 2 O 3 were successfully exploited for enhanced photocatalytic antibiotic degradation (ciprofloxacin, k = 0.0116 min –1 ), heavy-metal reduction (Cr 6+, k = 0.0752 min –1 ), and inactivation of water pathogens ( Vibrio cholerae, 96.5% in 40 min). The biocompatible nature of the ternary heterostructure was also ascertained from a hemagglutination study. An S-scheme charge transfer mechanism promoted by plasmonic hot electron injection from Ag nanodots coupled with a robust • OH radical generation ability accounted for the observed photocatalytic and photoantibacterial activity of the ternary composite.