(1. Materials Institute of Atomic and Molecular Science, Shaanxi University of Science and Technology, Xi’an 710021, China) (2. School of Materials Science & Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China.)
A catalyst of graphitic carbon nitride (g-C3N4) loaded with ruthenium (Ru) single atoms was synthesized by the method of solid phase in-situ reduction successfully. The results showed that Ru was dispersed on the surface of g-C3N4 as single atoms, and the loading of Ru reduced in-plane repeating units of g-C3N4. Through the analysis of FTIR, it was found that there were cyano groups in the catalyst, which led to the molecular structural defect. Both Ru atoms and cyano groups were electron acceptors, which could accelerate the transfer of photogenerated electrons and acted as photocatalytic active sites. After loading with Ru atoms, the light absorption range of g-C3N4 was widened and the absorption intensity was enhanced. Thus, the catalyst had excellent activity. Its photocatalytic nitrogen fixation efficiency was as high as 113.23 μg·g-1cat·h-1, 2.7 times that of the bare g-C3N4 catalyst. Meanwhile, the catalyst of g-C3N4 supported by Ru atoms also showed good stability, and the photocatalytic nitrogen fixation efficiency remained at 106.75 μg·g-1cat·h-1 after five cycles. In addition, the photocatalytic nitrogen fixation mechanism of the catalyst was investigated by PL, EIS and other characterization methods, in which nitrogen, ultrapure water and illumination were necessary conditions for the photocatalytic nitrogen fixation of the catalyst.