Curvature and defect formation synergistically promote the photocatalysis of ZnO slabs

Abstract

Crystal defects and morphological modifications are popular strategies to enhance the catalytic activity of heterogeneous semiconductor photocatalysts. Despite defect engineering and morphology control show their successful applications in ZnO, the effects of curved surface modifications on the photocatalytic performance of ZnO and their interplay with the defect formation remain unclear. To resolve this puzzle, we systemically investigate the joint effects of curvature and defect formation on the electronic structure, optoelectronic properties, and photocatalytic performance of ZnO slabs using first-principles calculations. We find that curvature deformation effectively narrows the electronic bandgap by up to 1.6 eV and shifts the p-/d-band centers, thereby enhancing light absorption in the visible and near-ultraviolet regions. Besides, curvature deformation stimulates self-polarization, facilitating the separation of photo-generated electrons and holes. Also, curvature deformation promotes the formation of defects by reducing defect formation energy (by up to 1.0 eV), thus creating abundant reaction sites for photocatalysis. Intriguingly, the synergistic interaction between curvature and defect deformation further strengthens the self-polarization, narrows the electronic bandgaps, adjusts the p-/d-band centers to improve the optoelectronic properties, and influences the dissociation and free energy barriers of intermediates. Consequently, our findings reveal that this synergy substantially enhances the photocatalytic performance of ZnO slabs, providing deeper insights into the role of defect engineering and morphology control on photocatalysis.