Synergy-Compensation Effect of Ferroelectric Polarization and Cationic Vacancy Collaboratively Promoting CO2 Photoreduction

Small. 2022 Nov 23;e2203559. doi: 10.1002/smll.202203559. Online ahead of print.

Abstract

Photocatalytic CO2 reduction is severely limited by the rapid recombination of photo-generated charges and insufficient reactive sites. Creating electric field and defects are effective strategies to inhibit charge recombination and enrich catalytic sites, respectively. Herein, a coupled strategy of ferroelectric poling and cationic vacancy is developed to achieve high-performance CO2 photoreduction on ferroelectric Bi2 MoO6 , and their interesting synergy-compensation relationship is first disclosed. Corona poling increases the remnant polarization of Bi2 MoO6 to enhance the intrinsic electric field for promoting charge separation, while it decreases the CO2 adsorption. The introduced Mo vacancy (VMo ) facilitates the adsorption and activation of CO2 , and surface charge separation by creating local electric field. Unfortunately, VMo largely reduces the remnant polarization intensity. Coupling poling and VMo not only integrate their advantages, resulting in an approximately sevenfold increased surface charge transfer efficiency, but also compensate for their shortcomings, for example, VMo largely alleviates the negative effects of ferroelectric poling on CO2 adsorption. In the absence of co-catalyst or sacrificial agent, the poled Bi2 MoO6 with VMo exhibits a superior CO2 -to-CO evolution rate of 19.75 µmol g-1 h-1 , ≈8.4 times higher than the Bi2 MoO6 nanosheets. This work provides new ideas for exploring the role of polarization and defects in photocatalysis.

Keywords: Bi 2MoO 6; CO 2 reduction; Mo vacancies; charge separation; polarization electric field.