Polarization-Inducible Metal–Semiconductor Transition and Bifunctional Catalysis in Sc2CO2/ZrSeO Heterostructures

Abstract

Solar-driven photocatalytic water splitting represents a pivotal strategy for addressing global energy shortages and environmental degradation. Although van der Waals (vdW) heterostructures enhance carrier efficiency via band engineering, their intrinsic electric fields are often restricted by fixed work functions. Taking the ferroelectric Sc₂CO₂ monolayer with switchable polarization and the Janus ZrSeO monolayer with strong visible-light absorption as a representative system, first-principles calculations are employed to investigate the band alignment, carrier transport behavior, and photocatalytic efficacy of the Sc₂CO₂/ZrSeO ferroelectric heterojunction. The study reveals that the interplay between the switchable Sc₂CO₂ polarization and the intrinsic ZrSeO dipole explicitly governs the electronic properties. Combining the two ZrSeO orientations with the two Sc₂CO₂ ferroelectric states yields tunable semiconducting bandgaps (0.76–1.50 eV) and establishes a Type-II band alignment in specific configurations, promoting efficient carrier separation alongside enhanced visible-light absorption. Crucially, at a fixed ZrSeO orientation, reversing the Sc₂CO₂ polarization induces a reversible metal-to-semiconductor transition. Gibbs freeenergy calculations further evaluate the catalytic performance of these representative semiconducting and metallic configurations. These findings highlight the Sc₂CO₂/ZrSeO heterostructure’s potential for multifunctional catalytic applications and ferroelectric electronic devices.