Mechanical Control of Photocatalysis in 2D Ferroelectrics

Strain is a conventional mechanical means for optimizing light absorption of photocatalysts. Herein, an additional degree of freedom-ferroelectricity is introduced into this process, enhancing not only solar absorption but also photogenerated carrier separation and carrier-driven forces through opto-electro-mechanical coupling. This approach is illustrated using a 2D ferroelectric material, In2Se3. The findings show that strain can adjust its bandgap for improved absorption and solar-to-hydrogen efficiency, and can also change its polarization to selectively control water-splitting products. Specifically, strain manipulation can tune the bandgap within a range of 0.5-1.5 eV, thereby better aligning it with the solar spectrum, and increasing solar-to-hydrogen conversion efficiency to 6.6%. Additionally, strain-induced changes in the polarization (internal electric field) of ferroelectric In2Se3 can alter redox potentials, selectively promoting hydrogen or oxygen reduction on the surface by ferroelectric switching. These findings provide a theoretical basis for designing and optimizing efficient 2D ferroelectric photocatalysts.