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.