Porosity-Triggered Efficient Single-Atom Catalysis in Two-Dimensional Materials.

Single-atom catalysts (SACs) promise maximum atomic utilization and enhanced intrinsic activity, yet their high surface energy results in thermal instability and sintering, hindering practical application. While lattice confinement stabilizes SACs, conventional 3D frameworks (e.g., MOFs) suffer from insulating behavior and inefficient pore-size control, compromising intrinsic catalytic efficiency. To overcome this, we introduce a novel lattice confinement paradigm using engineered two-dimensional porous monolayers. These hosts, designed via the "superatom" concept, possess intrinsic sub-nanometer pores that enforce a strong quantum confinement effect on anchored single atoms. We used first-principles calculations to screen 224 candidates, identifying stable hosts with diverse electronic properties. Evaluation of the hydrogen evolution reaction revealed superior catalytic performance over conventional doped architectures. This enhancement stems from the strong confinement effect, enabling precise, localized electronic control over the catalytic properties via active-site charge redistribution. Our work establishes a viable and electronically robust strategy for designing next-generation catalysts with tailored properties.