Fabricating carbon nitride-based 3D/0D intramolecular donor–acceptor catalysts for efficient photoreduction of CO2

Abstract

Mass transfer efficiency and charge carrier behavior are two crucial factors affecting the photocatalytic performance of a catalyst. Donor–acceptor (DA) structure has shown great potential in facilitating charge carrier migration, extending light response region, and regulating bandgap structure. In this work, a kind of new three-dimensional carbon nitride (3D CN) with the intramolecular DA structure was prepared by incorporating perylene-3,4,9,10-tetracarboxylicdianhydride (PY) into the structure of 3D CN and applied for the photoreduction of CO₂. The 3D structure greatly improved the specific surface area and facilitated the mass transfer of reactants. Meanwhile, it offered ample active sites for CO₂ reduction as well. The introduction of PY into 3D CN led to the formation of the intramolecular DA structure, resulting in a new transition state and remarkably extends the visible light response range. In addition, the spatial separation of electrons and holes in the DA structure significantly reduced the recombination of electron–hole pairs and accelerated the migration of charge carriers. The 3D and DA structures synergistically catalyzed the photoreduction of CO₂ with high efficiency and afforded a CO evolution rate of 10.34 μmol g⁻¹ h⁻¹, which is about 10 times higher than 3D CN. A possible reaction mechanism was proposed. Moreover, the reaction was carried out in the absence of any additive, which makes it green and sustainable.