Facilitating Charge Separation and CO2 Adsorption in g-C3N4 by Fe Single Atoms on 2D Nitro-Oxygeneous Carbon for Efficient Artificial Photosynthesis.

Photocatalytic reduction of carbon dioxide (CO2), so-called artificial photosynthesis, has been regarded as the future technology with high potential to sustainably address global warming. However, the efficiency and stability of the catalysts used in this frontier technology are substantially lower than the requirement for practical application and need to be further improved, especially for gas-phase reactions. In this work, the composites of iron single-atom catalysts (Fe-SACs) supported on N/O-doped carbon and graphitic carbon nitride (g-C3N4) were fabricated to promote the gas-solid phase photocatalytic CO2 reduction under the simulated sunlight. Insightful characterizations reveal that g-C3N4 could function as a CO2 capture and light-absorber, while the Fe-SACs act as a promotor for charge-carrier separation. Hence, the catalytic performance was greatly increased compared to that of the individual component. For example, the individual thin g-C3N4 (T-CN) and Fe-SAC can generate total reduced CO2 products of 5.06 and 0.75 μmol.h-1g-1, respectively. On the other hand, the reduced CO2 products were increased by more than doubled (14.62 μmol.h-1g-1) when the composite of T-CN/Fe-SAC was used as a catalyst. The photocatalytic enhancement could be attributed to the synergistic effects between Fe-SAC/T-CN which possess the stronger CO2 adsorption ability and charge separation capability and the increased number of active sites, resulting in the improved overall performance.