High-Performance Photocatalytic Hydrogen Production and Degradation of Levofloxacin by Wide Spectrum-Responsive Ag/Fe3O4 Bridged SrTiO3/g-C3N4 Plasmonic Nanojunctions: Joint Effect of Ag and Fe3O4.

Highly photoresponsive semiconductor photocatalysis for energy and environmental applications require judicious choice and optimization of semiconductor interfaces for wide spectral capabilities. This work aims at rational designing of highly active SrTiO3/g-C3N4 junctions bridged with Ag/Fe3O4 nanoparticles for utilizing Z-scheme transfer and surface plasmon resonance effect of Ag augmented by iron oxide. The SrTiO3/(Ag/Fe3O4)/g-C3N4 (SFC) catalyst was employed for photocatalytic hydrogen production and photodegradation of levofloxacin (LFC; 20 mg/L) under UV, visible, near infra-red, and natural solar light exhibiting high performance. Under visible light (<780 nm), SFC-3 sample (30 wt % g-C3N4 and 3% Ag/Fe3O4) shows a H2 evolution of 2008 μmol g-1 h-1 which is ∼14 times that of bare g-C3N4. In addition, 99.3% removal of LFC was degraded in 90 min under visible light with retention of activity under sun. The inherent topological properties, complete, higher charge separation, and reduced recombination allowed this catalyst for a high photocatalytic response which was proved by UV-diffuse reflectance spectroscopy, photoluminescence, electrochemical impedance spectroscopy, and photocurrent response measurements. Scavenging experiments and electron spin resonance analysis reveal that the mechanism shifts from a dual charge transfer in case of binary junction to essential Z-scheme with incorporation of Ag/Fe3O4. Both •O2- and •OH are main active radicals in visible light, whereas •O2- majorly participate under UV. The synergistic effect of SrTiO3, g-C3N4, and plasmon resonance of Ag/Fe3O4 not only improves light response and reduce recombination but also enhances the redox-ability of charge carriers. A H2 production mechanism and LFC degradation pathway (degradation, defluorination, and hydrolysis) has been predicted. This work paves a way for development of photocatalysts working in practical conditions for pollution and energy issues.