Enabling high-efficiency plasmon-induced visible-light-driven reduction of hexavalent chromium with Au-TiO2/Shewanella biohybrid

Abstract

The application of microbe-photocatalyst biohybrid (MPB) systems to pollutant removals has drawn considerable attentions due to the high demands on energy shortage and environmental pollution prevention. However, the stability and utilization rate of photoelectrons generated under the photocatalysis of plasmonic metals are still low. Herein, we constructed a new Au-TiO₂/Shewanella biohybrid system by combining photocatalyst and electrogenic bacteria to realize the plasmon-induced visible-light-driven reduction of hexavalent chromium. The highly hydrophilic Au-TiO₂ and the outer membrane protein (OmcA) of Shewanella were effectively complexed to form a tight composite. The irradiation of visible light increases the expression level of extracellular polymeric substances (EPS) in the MPB system and upregulates the function gene of OmcA and MtrC, suggesting that the photoelectrons are absorbed by the conductive protein and deposited into the microbes to realize high efficiency chromium removal (68.9%). This study successfully utilize the photogenerated electrons under the catalysis of plasmonic gold nanoparticles and opens up a new avenue to the application of MPB system in water treatment.