Plasmonic Bi/ZnWO₄ microspheres with improved photocatalytic activity on NO removal under visible light

In this work, bismuth (Bi) nanoparticle anchored ZnWO4 microspheres (Bi/ ZnWO₄) were prepared and used as robust and efficient photocatalysts for NO removal at parts-per-billion level under visible light irradiation. The as-synthesized composite with a proper mass ratio of Bi (50%) displayed a higher reaction rate (0.067 min⁻¹) than its single counterparts ZnWO₄ (0.004 min⁻¹) and Bi (0.027 min⁻¹), respectively. Due to the surface plasmon resonance (SPR) effect of Bi nanoparticles, the Bi/ ZnWO₄ composites showed broad light absorption in the visible spectrum. Moreover, the formation of the Bi/ZnWO₄ heterointerface promoted the separation of photoexcited electron-hole pairs, which is demonstrated by the increased photocurrent density in comparison to the pristine materials. The above characteristics endowed the Bi/ZnWO₄ composites with superior photocatalytic activity for NO removal. The radical scavanger tests revealed that the superoxide radical was the main active species to initiate NO oxidation, while the hydroxyl radical was not involved in the process. This study shows practical value in air pollutant abatement, because it provides an economical and feasible route to fabricate SPR-enhanced composite photocatalysts using earth abundant Bi material instead of noble metals. Copyright © 2016 American Chemical Society.