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

Photocatalytic reduction of carbon dioxide (CO 2 ) to solar fuel is a potential approach to overcome the problem of high CO 2 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 FeCl 3 ·6H 2 O as raw materials. The performances of the resulting materials toward the photocatalytic reduction of CO 2 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 CO 2 illustrated conversion yield of CO 2 to CH 3 OH 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 CO 2 .