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

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 (V_Mo ) facilitates the adsorption and activation of CO₂ , 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 CO₂ adsorption. In the absence of co-catalyst or sacrificial agent, the poled Bi₂ MoO₆ with V_Mo 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.