Photon‐Resilient CsPbBr 3 Nanocrystals Achieved Through Cation‐Ligand Synergistic Surface Engineering for Cocatalyst‐Free High‐Performance CO 2 Photoreduction

ABSTRACT Lead halide perovskite nanocrystals (PNCs) combine strong light harvesting with favorable excited‐state properties for solar‐fuel synthesis, yet their application in CO 2 photoreduction is limited by rapid photoinduced surface degradation. Here, we overcome this limitation through cooperative cation‐ligand engineering of CsPbBr 3 PNCs by integrating surface‐associated Zn 2 + with short‐chain isophthalic acid (IPhA). This dual surface coordination reinforces halide bonding, stabilizes undercoordinated Pb sites, suppresses defect propagation, prolongs carrier lifetime, increases carrier density, and reduces charge‐transfer resistance. Mechanistic investigations, including operando Raman spectroscopy and CO‐stripping voltammetry, reveal sustained surface‐bound intermediates and favorable CO adsorption–desorption behavior during CO 2 reduction. Consequently, the Zn‐IPhA engineered PNCs sustain continuous CO and CH 4 evolution for 10 h under simulated solar irradiation and retain high activity over three consecutive 10 h cycles with only marginal performance loss. The engineered PNCs deliver cocatalyst‐free CO evolution rates of ∼55 and ∼64 µmol g −1 h −1 together with CH 4 evolution rates of ∼20 and ∼26 µmol g −1 h −1 under white‐light (1 Sun) and UV irradiation, respectively, representing the highest reported productivities among 3D PNC photocatalysts and surpassing many cocatalyst‐integrated systems. These findings establish cooperative surface coordination engineering as a general strategy for developing photon‐resilient perovskite photocatalysts for solar‐fuel generation.