Reinforcing 2D Single‐Crystal Bi₂O₂CO₃ with Additional Interlayer Carbonates by CO₂‐Assisted Solid‐to‐Solid Phase Transition

Abstract A facile gaseous CO₂ mediated solid‐to‐solid transformation principle is adopted to insert additional CO₃²⁻ anions into the thin single‐crystal nanosheets of Bi₂O₂CO₃, which is built of periodic arrays of intrinsic CO₃²⁻ anions and (Bi₂O₂)²⁺ layers. The additional CO₃²⁻ anions create abundant defects. The Bi₂O₂CO₃ nanosheets with rich interlayer CO₃²⁻ exhibit superior electronic properties and charge transfer kinetics than the pristine single‐crystal 2D Bi₂O₂CO₃ and display enhanced catalytic activity in photocatalytic CO₂ reduction reaction and the photocatalytic oxidative degradation of organic pollutants. This work thus illustrates interlayer engineering as a flexible means to build layered 2D materials with excellent properties.