Enhanced Solar CO₂ Reduction Using Single Cobalt Sites on Carbon Nitride Modified with a Dianhydride

Photoactive single-atom catalysts (SACs) are among the most exciting catalytic materials for solar fuel production. Different SACs, including our own Co SACs, have been prepared on graphitic carbon nitride (C₃N₄) for use in photocatalysis. Building on our prior success, we report here doped C₃N₄ using various supplemental carbon dopants as the support for Co SACs. The Co SAC on a dianhydride-doped C₃N₄ showed the highest activity in photocatalytic CO₂ reduction. Catalyst characterization was carried out to explore the origin of the enhanced activity of this particular Co SAC. The dianhydride-doped C₃N₄ possesses unique microstructural features, including a large interlayer space and fibrous morphology, that could contribute to enhanced photocatalytic activity. Our results further indicate that dianhydride is the most effective dopant to incorporate aromatic moieties in C₃N₄, which resulted in improved charge separation and enhanced activity in photocatalysis.