A novel plasmonic Z-scheme photocatalyst for solar-light-driven degradation of naphthalene in seawater: Degradation pathways and mechanism insight

Abstract

In this study, a plasmonic Z-scheme AgBr/Ag/SnO2 photocatalytic system is constructed for the removal of naphthalene (NAP) in seawater under sunlight irradiation by chemical precipitation, photo-reduction, and sol-gel methods. The effects of irradiation time, initial NAP concentration, catalyst dosage, pH value, seawater salinity, reaction solution type, organic pollutant type, and cycle time on the performance of the AgBr/Ag/SnO2 photocatalyst are investigated. The possible degradation pathways of NAP in seawater are speculated. Moreover, a potential mechanism for the plasmonic Z-scheme photocatalytic system is presented. The results demonstrate that the AgBr/Ag/SnO2 photocatalyst achieves a maximal NAP removal efficiency of 95.05 % in seawater under 2.0 g/L catalyst, 8.0 pH, 62.5 gNaCl/L salinity and 120 min sunlight irradiation. The deposited Ag nanoparticles can absorb visible light, which then induces the surface plasmon resonance (SPR) effect and functions as the electronic medium in the plasmonic Z-scheme photocatalytic system. Among all the active species, hydroxyl radical (•OH) contributes the most to the removal of NAP using the AgBr/Ag/SnO2 photocatalyst. Furthermore, the AgBr/Ag/SnO2 photocatalyst exhibits excellent recyclability and good stability. Based on these results, the proposed plasmonic Z-scheme photocatalytic technology has great potential for the removal of polycyclic aromatic hydrocarbons (PAHs) in seawater in practical application.