Synergy-Compensation Effect of Ferroelectric Polarization and Cationic Vacancy Collaboratively Promoting CO 2 Photoreduction.

Photocatalytic CO 2 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 CO 2 photoreduction on ferroelectric Bi 2 MoO 6 , and their interesting synergy-compensation relationship is first disclosed. Corona poling increases the remnant polarization of Bi 2 MoO 6 to enhance the intrinsic electric field for promoting charge separation, while it decreases the CO 2 adsorption. The introduced Mo vacancy (V Mo ) facilitates the adsorption and activation of CO 2 , and surface charge separation by creating local electric field. Unfortunately, V Mo largely reduces the remnant polarization intensity. Coupling poling and V Mo not only integrate their advantages, resulting in an approximately sevenfold increased surface charge transfer efficiency, but also compensate for their shortcomings, for example, V Mo largely alleviates the negative effects of ferroelectric poling on CO 2 adsorption. In the absence of co-catalyst or sacrificial agent, the poled Bi 2 MoO 6 with V Mo exhibits a superior CO 2 -to-CO evolution rate of 19.75 µmol g -1 h -1 , ≈8.4 times higher than the Bi 2 MoO 6 nanosheets. This work provides new ideas for exploring the role of polarization and defects in photocatalysis.