Single Ru atoms confined into MOF/C3N4 for dual improved photocatalytic carbon dioxide reduction and nitrogen fixation

Photocatalytic carbon dioxide reduction reaction (CO2RR) and nitrogen reduction reaction (NRR) are two promising directions in new energy development. However, the majority of studies thus far have focused on a single reaction of catalysts (CO2RR or NRR). Herein, we have in-situ synthesized Ru/MOF/C3N4 catalyst by confining the Ru single atom in Metal organic framework (MOF). We separately characterize the photocatalytic CO2RR and NRR of the catalysts (CO2RR: gas–solid mode; NRR: liquid–solid mode) and find that Ru/MOF/C3N4 exhibits excellent catalytic activities and recyclability in both CO2RR and NRR. The presence of Ru single atoms results in energy levels in the bandgap of MOF, which prevents the formation of electron-hole complex and increases the concentration of photogenerated carriers. In addition, it hinders the hydrogen evolution reaction (HER) and reduces the Gibbs free energy of the CO2RR and NRR. These results provide not only insights into promoting the activity of single-atom catalysts in a dual-catalytic system but also guidance for future studies on direct air photocatalysis.