Self-doping and surface plasmon modification induced visible light photocatalysis of BiOCl

Abstract

In this study we demonstrate that self-doping and surface plasmon resonance could endow a wide-band-gap ternary semiconductor BiOCl with remarkable visible light driven photocatalytic activity on the degradation of organic pollutants and photocurrent generation properties. The self-doped BiOCl with plasmonic silver modification was synthesized by a facile one-pot nonaqueous approach and systematically characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-visible diffuse reflectance spectra, electron spin resonance, and X-ray photoelectron spectroscopy. The photocurrent enhancement was found to be intimately dependent on the irradiation wavelength and matched well with the intensity of the absorption of the Ag nanoparticles. Reactive species trapping experiments and electron spin resonance spectroscopy with 5,5-dimethyl-1-pyrroline-N-oxide spin-trapping adducts confirmed that more oxidative species could be generated from the photogenerated electrons due to the plasmon-excitation of the metallic Ag in the self-doped BiOCl with plasmonic silver modification, which is responsible for the great enhancement of photocatalytic activity and photocurrent. Surface photovoltage spectroscopy and time-resolved photoluminescence spectroscopy results revealed the transfer of plasmon-band-induced electrons from Ag nanoparticles into BiOCl and the acceleration effect of surface plasmon resonance-induced intense oscillating electric fields on this electron transfer. This study would not only provide direct evidence of plasmonic photocatalysis, but also shed light on the design of highly efficient metal-semiconductor composite photocatalysts.