Assembling MOF‐Based (NH ₄ ) _0.8 TiOF _2.8 @Fe‐pyz p ‐ n Heterojunction Through L ‐Cysteine for CO ₂ Photoreduction

ABSTRACT Metal organic frameworks (MOFs) have been widely studied in photocatalytic CO ₂ reduction reaction (CO ₂ RR). However, pristine MOFs exhibit low utilization of light, severe recombination of photogenerated carriers and low intrinsic photocatalytic efficiency. In response to the above issues, this paper constructs (NH ₄ ) _0.8 TiOF _2.8 @Fe‐pyz p‐n heterojunction photocatalysts through self‐assembling L‐ cysteine for photocatalytic CO ₂ RR. This composite photocatalyst exhibits excellent photocatalytic activity in reducing CO ₂ to high value‐added products (HCOOH, CO and CH ₄ ). Through experimental characterization and density functional theory (DFT) calculations, the structure‐activity relationship between the crystal structure, the band structure, the photogenerated carrier separation and the catalytic performance of (NH ₄ ) _0.8 TiOF _2.8 @Fe‐pyz was systematically studied, revealing that the built‐in electric field in the interface of the p‐n heterojunction promotes the photogenerated carrier separation, and the active centers are clarified for CO ₂ reduction half‐reaction on (NH ₄ ) _0.8 TiOF _2.8 and H ₂ O oxidation half‐reaction on Fe‐pyz separately. This work demonstrates that rational design of heterojunctions can regulate the structure‐activity relationship and open up a new avenue for the fabricating of highly efficient MOF‐based CO ₂ RR photocatalysts.