Enhancement of piezophototronic hydrogen evolution reaction through the polarization of ferroelectric Bi4Ti3O12 microplates

In this study, we analyzed the properties of Bi4Ti3O12 microplates in the context of hydrogen evolution reaction. Piezoresponse force microscopy revealed a typical butterfly curve, indicating that as-synthesized Bi4Ti3O12 exhibits ferroelectric properties. Under ultrasonication, the amount of hydrogen produced by polarized (2000 V) Bi4Ti3O12 increased from 728 to 1349 μmol g−1, which was 1.85 times higher than that generated by unpolarized Bi4Ti3O12. The increase in hydrogen evolution rate may be attributed to the gradual alignment of polarization within the ferroelectric domains of Bi4Ti3O12. Moreover, with synergistic piezophototronic activity, the amount of hydrogen produced by Bi4Ti3O12 was further increased to 1478 μmol g−1, which was 200% higher than that generated by unpolarized Bi4Ti3O12. Theoretical calculations revealed that Bi4Ti3O12 microplates exhibit a high piezoelectric potential along the x-axis, which is consistent with the spontaneous polarization of the microplates. By applying an external polarization field, ferroelectric polarization was activated to effectively separate free charges and extend carrier lifetime (from 0.6 to 0.84 ns). The application of an external electric field to ferroelectric Bi4Ti3O12 appears to be a favorable strategy for enhancing its piezophototronic activity. Our findings may facilitate future studies in the fields of environmental science and renewable energy.