Title

Hierarchical porous ZnWO4 microspheres synthesized by ultrasonic spray pyrolysis: Characterization, mechanistic and photocatalytic NOx removal studies

Authors

Huang, Y; Gao, YX; Zhang, Q; Cao, JJ; Huang, RJ; Ho, WK; Lee, SC

Abstract

Solar-light-driven photocatalysts with porous structure are preferred for gaseous pollutants removal at low concentration levels. In this study, hierarchical porous ZnWO₄microspheres were synthesized by a facile ultrasonic spray pyrolysis method for the first time. The as-prepared ZnWO₄samples were composed of microspheres with diameter ranging from 0.1 to 2 pm and it was revealed that these micro spheres are formed by the self-assembly of nanoparticles. The photocatalytic performances of these microspheres were evaluated by the degradation of gaseous NOx under simulated solar light irradiation. It was found that the ZnWO4 batch synthesized at 700℃exhibited superior photocatalytic activity to those synthesized at 650℃and 750℃as well as Degussa TiO₂P25. Both·OH and O₂·^-radicals were found to be the major reactive species involved for NOx degradation as identified by electron spin resonance spectroscopy (ESR) method, which was consistent with the theoretical analysis. The excellent catalytic activity of ZWO-700 was attributed to its special hierarchical porous structure, which facilitated the separation/diffusion of the photogenerated charge carriers and the diffusion of intermediates and final products of NOx oxidation. The photocatalytic NOx removal mechanism over ZnWO₄samples was also proposed. This study suggests that ultrasonic spray pyrolysis is a facile and scalable process to fabricate ZnWO₄porous microspheres which are promising photocatalytic materials for gaseous pollutants purification.

Corresponding author

Huang Yu

Volume

515

Issue

Page

170-187

Pub year

April, 2016

Publication name

Applied Catalysis A-General

Details

http://www.sciencedirect.com/science/article/pii/S0926860X1630062X