Regulating π-π Stacking Interactions to Boost Near-Infrared Light-Driven CO₂ Reduction

Developing highly efficient photocatalysts to achieve near-infrared (NIR) light-driven CO₂ reduction is of great significance yet remains a great challenge. In this article, we found that BODIPY-based π frameworks can serve as good NIR photocatalysts, achieving highly efficient CO₂ reduction to HCOO^- coupled with benzyl alcohol oxidation to benzaldehyde in pure water. More impressively, the photocatalytic performance of these π frameworks can be improved by regulating π-π stacking interactions, among which the optimized π-pyrenyl (π-PY) framework with the most π-π stacking interactions exhibits HCOO^- production rates of 4045 and 1693 µmol g^-1 h^-1 in >99% and 15% CO₂ atmospheres, respectively. π-PY, thus, stands for the current state-of-the-art photocatalyst in NIR-light-driven CO₂ reduction. Experiments together with theoretical calculations demonstrated that the high photocatalytic activity of π-PY could be due to the abundant π-π stacking interactions, which accelerates charge separation and transfer, as well as prolongs carrier lifetime and reduces energy gap. This work gives new insights in understanding the contribution of π-π stacking interactions to photocatalysis, and introduces a new strategy for developing efficient photocatalysts for NIR-light-driven CO₂ reduction.