Tip-induced electronic polarization at the atomic scale: a mechanistic framework for enhanced water dissociation

Tip effects exhibit unique advantages in a variety of application scenarios covering both civilian and cutting-edge fields. However, the further development of conventional tip-based structures is intrinsically limited by the complex thermo-mechano-electromagnetic interplay arising from strong multi-physical field coupling. Herein, a single-atom tip structure (SATS) model is proposed through accurate density functional theory (DFT) based on symmetry breaking and quantum confinement effects. We successfully demonstrate the powerful capability of SATSs to modulate local charge density and further predict the enormous potential of copper SATSs for promoting the catalysis of water dissociation. Specifically, water dissociation can be enabled at a mild temperature (350 K) owing to the reduced dissociation barriers adjacent to copper SATSs, which arise from both charge-injection-induced intense local fields and a core-shell electronic configuration. The abnormal homogenization observed when the number of atomic layers in SATSs reaches a certain level further indicates a unique mechanism of the SATS effect compared to the common behavior of macroscopic charge distribution, which is solely correlated with curvature. This work provides a theoretical basis for overcoming the low efficiency and yield of water dissociation via a design principle for quantum-confined electrocatalysts. In addition to the anticipated breakthrough in water harvesting, the strategy of atomic-scale tip engineering may be extended to related fields such as photocatalysis, electronic structure regulation, and matter transport or capture.