Ultrathin Co_0.85Se nanosheet cocatalyst for visible-light CO₂ photoreduction

Ultrathin Co_0.85Se nanosheets were prepared via a facile solvothermal method, which successfully overcome the disadvantage of insufficient active sites in bulk Co_0.85Se by reducing its thickness into the atomic scale. Co_0.85Se nanosheets have been found to be efficient cocatalysts for photocatalytic CO₂ reduction with TON as high as 58 in 1 h reaction under visible-light irradiation. Compared with bulk Co_0.85Se blocks, the ultrathin nanosheet samples exhibited nearly 2.5 times higher activity in CO₂ photoreduction. The metal-like character and ultrathin 2D structure of Co_0.85Se nanosheets support the superb charges transfer and rich CO₂ adsorption sites exposure for surface catalysis. A relationship between the surface structure and the cocatalytic activity was established. These results not only demonstrate the potential of a notable, affordable and earth-abundant CO₂ photoreduction cocatalyst based on ultrathin Co_0.85Se nanosheets but also provide a guidance in the exploration of excellent active and durable cocatalysts/catalysts to replace noble metals for artificial photosynthesis.