Defect Engineering Centrosymmetric 2D Material Flexocatalysts

Abstract

In this study, the flexoelectric characteristics of 2D TiO₂ nanosheets are examined. The theoretical calculations and experimental results reveal an excellent strain‐induced flexoelectric potential (flexopotential) by an effective defect engineering strategy, which suppresses the recombination of electron–hole pairs, thus substantially improving the catalytic activity of the TiO₂ nanosheets in the degradation of Rhodamine B dye and the hydrogen evolution reaction in a dark environment. The results indicate that strain‐induced bandgap reduction enhances the catalytic activity of the TiO₂ nanosheets. In addition, the TiO₂ nanosheets degraded Rhodamine B, with k_obs being ≈1.5 × 10⁻² min⁻¹ in dark, while TiO₂ nanoparticles show only an adsorption effect. 2D TiO₂ nanosheets achieve a hydrogen production rate of 137.9 µmol g⁻¹ h⁻¹ under a dark environment, 197% higher than those of TiO₂ nanoparticles (70.1 µmol g⁻¹ h⁻¹). The flexopotential of the TiO₂ nanosheets is enhanced by increasing the bending moment, with excellent flexopotential along the y‐axis. Density functional theory is used to identify the stress‐induced bandgap reduction and oxygen vacancy formation, which results in the self‐dissociation of H₂O on the surface of the TiO in the dark. The present findings provide novel insights into the role of TiO₂ flexocatalysis in electrochemical reactions.