Defects Regulation Through Halogenation-Modification for Enhanced Photocatalytic Carbon Dioxide Reduction

Abstract

Modulating the band structure of semiconductor photocatalysts to increase the photocatalytic CO2 reduction activity has become a great challenge for sustainable energy conversion. Herein, the halogenation-modified defective Bi2WO6 nanosheets have been successfully prepared to address aforementioned challenge. The modification of halogenation atoms can promote the defective Bi2WO6 nanosheets to generate more oxygen defects, and the concentration of oxygen vacancy in Bi2WO6 nanosheets can be controlled by modifying with different halogenation atoms. Importantly, the modification of halogenation atoms can modulate the band structure of Bi2WO6 and optimize the separation and transport of photogenerated carriers. As a result, all the halogenation-modified defective Bi2WO6 nanosheets manifested an enhanced photocatalytic CO2 reduction activity. Specially, the Br-Bi2WO6 exhibited the best CO generation rate of 13.8 μmol g-1 h-1, and displayed roughly 7.3 times as high as that of defective Bi2WO6 (1.9 μmol g-1 h-1). Moreover, in the coexistence of cocatalysts (CoPc) and sacrificial agents (TEOA), the Br-Bi2WO6 exhibited superior CO generation rate of 187 μmol g-1 h-1. This finding provides a new approach to simultaneously modulate the concentration of oxygen vacancy and band structure of semiconductor photocatalysts, developing highly efficient CO2 reduction photocatalysts.