Semiconductor/Covalent‐Organic‐Framework Z‐Scheme Heterojunctions for Artificial Photosynthesis

A strategy to covalently connect crystalline covalent organic frameworks (COFs) with semiconductors to create stable organic–inorganic Z‐scheme heterojunctions for artificial photosynthesis is presented. A series of COF–semiconductor Z‐scheme photocatalysts combining water‐oxidation semiconductors (TiO 2 , Bi 2 WO 6 , and α‐Fe 2 O 3 ) with CO 2 reduction COFs (COF‐316/318) was synthesized and exhibited high photocatalytic CO 2 ‐to‐CO conversion efficiencies (up to 69.67 μmol g −1  h −1 ), with H 2 O as the electron donor in the gas–solid CO 2 reduction, without additional photosensitizers and sacrificial agents. This is the first report of covalently bonded COF/inorganic‐semiconductor systems utilizing the Z‐scheme applied for artificial photosynthesis. Experiments and calculations confirmed efficient semiconductor‐to‐COF electron transfer by covalent coupling, resulting in electron accumulation in the cyano/pyridine moieties of the COF for CO 2 reduction and holes in the semiconductor for H 2 O oxidation, thus mimicking natural photosynthesis.