Preparation of Iron-Doped Carbon Dots for Enhanced Photocatalytic Carbon Dioxide Reduction

Photocatalytic reduction of carbon dioxide (CO2) to solar fuel is a potential approach to overcome the problem of high CO2 concentrations; however, the process still faces enormous challenges, such as low light absorption efficiency and high carrier recombination rates. Herein, Fe-doped carbon dots were prepared by a one-step hydrothermal method using sodium citrate, ethylenediamine, and FeCl3·6H2O as raw materials. The performances of the resulting materials toward the photocatalytic reduction of CO2 were investigated and the results showed that Fe doping can regulate the energy band structure of CDs. However, the conduction band potential of Fe-carbon dots displayed no obvious influence except in terms of band gap. Moreover, Fe doping reduced the recombination rate of photo-generated carriers in CDs, increased the mobility of photo-generated carriers, and declined the resistance during the migration of photo-generated electrons. The photocatalytic reduction performances of CO2 illustrated conversion yield of CO2 to CH3OH reaching 289.81 μmol·g (cat)-1·h-1 using Fe-CDs-13.0 catalyst, a value 2.36-fold higher than that of CDs. We found that Fe-CDs were synthesized by modulating the energy band structure of CDs. Fe-CDs improve visible light utilization and apply them to the photocatalytic reduction of CO2.