Designing Spin-Selective ZnO-Based Single-Atom Catalysts through Surface Reconstruction Engineering

The catalytic behavior of single-atom catalysts (SACs) and magnetic single-atom catalysts (MSACs) strongly depends on the atomic-scale environment of the support. Reconstructed polar ZnO(0001) surfaces, stabilized by intrinsic Zn or O vacancies, provide distinct sites for transition-metal (TM) anchoring. Using spin-polarized density functional theory, we analyzed Pd, Pt, Rh, and Ru atoms on the (2×2)-VZn and (1×3)-VO reconstructions. A clear contrast arises between the two surfaces: on (2×2)-VZn, magnetism appears only when the TM substitutes a Zn atom, while the vacancy remains empty, producing positive electrostatic potentials that are favorable for spin-selective catalysis. In contrast, the (1×3)-VO reconstruction induces magnetism only for Ru substitution at Zn sites, with nearly neutral potentials for all TMs, suggesting limited catalytic enhancement. These results highlight the crucial role of surface reconstruction in tuning spin polarization and local charge, offering insights for the design of ZnO-based SAC and MSAC systems for oxygen and CO reduction reactions.