In nature, photosynthetic organelles harness solar radiation to produce energy-rich compounds from water and atmospheric CO2 via exquisite supramolecular assemblies. Although artificial photocatalytic cycles have been shown to occur at higher intrinsic efficiencies, the low selectivity and stability in water for multi-electron CO2 reduction hamper their practical applications. The creation of water-compatible artificial photocatalytic systems mimicking the natural photosynthetic apparatus for selective and efficient solar fuel production represents a major challenge. Here we show a highly stable and efficient artificial spherical chromatophore nanomicelle system self-assembled from Zn porphyrin amphiphiles with a Co catalyst in water for CO2-to-methane conversion with a turnover number >6,600 and 89% selectivity over 30 days. The hierarchical self-assembly induced a spherical antenna effect that could facilitate the photocatalytic process with an initial 15% solar-to-fuel efficiency. Furthermore, it has a capability to efficiently reduce atmospheric CO2 into methane with high selectivity in water.
Design of artificial photosynthetic systems that mimic the complex supramolecular structures in natural systems remains a grand challenge. Here self-assembled nanomicelles containing Zn porphyrins and Co porphyrins as photosensitizer and catalyst achieve selective photocatalytic CO2-to-CH4 conversion in water.