Dynamic aggregation of carbon dots self-stabilizes symmetry breaking for exceptional hydrogen production with near-infrared light

Developing new photosystems that integrate broad-band near-infrared (NIR) light harvesting and efficient charge separation is a long-sought goal in the photocatalytic community. In this work, we develop a novel photochemical strategy to prepare light-active carbon dots (CDs) under room temperature and discover that the aggregation of CDs can broaden the light absorption to the NIR region due to the electronic couplings between neighboring CDs. Importantly, the dynamic non-covalent interactions within CD aggregates can stabilize symmetry breaking and thus induce large dipole moments for charge separation and transfer. Furthermore, the weak non-covalent interactions allow for flexible design of the aggregated degrees and the local electronic structures of CD aggregates, further strengthening NIR-light harvesting and charge separation efficiency. As a result, the CD aggregates achieve a record apparent quantum yield of 13.5% at 800 nm, which is one of the best-reported values for NIR-light-driven hydrogen photosynthesis to date. Moreover, we have prepared a series of different CDs and also observed that these CDs after aggregation all exhibit outstanding NIR-responsive photocatalytic hydrogen production activity, suggesting the universality of aggregation-enhanced photocatalysis. This discovery opens a new promising platform for using CD aggregates as efficient light absorbers for solar conversion. Carbon dot (CD) aggregates exhibit strong light-harvesting from visible to NIR light region.Importantly, the aggregation of CDs can stabilize symmetry breaking and thus maintain a large dipole moment for charge separation. As a result, the CD aggregates can efficiently drive photocatalytic hydrogen production under low-energy NIR light irradiation.image