Synergistic effect of Cu and Fe on g-C3N4 for selective oxidation of methane to C1 products

The selective conversion of methane is a significant but difficult challenge. We reported a CuFe bimetallic catalyst supported by g-C 3 N 4 for the catalytic oxidation of methane to oxygenated C1 products. Using H 2 O 2 as the oxidant, Cu 0.4 Fe 0.3 -C 3 N 4 catalyst had a C1 yield of 8231 μmol·g cat −1 · h −1 at 70 °C, and 1 H NMR results showed that almost all of the liquid phase products were target C1 products. The methanol selectivity on CuFe-C 3 N 4 was 44.5 %, comparing with 20.2 % methanol selectivity on Cu-C 3 N 4 . The formation of a Cu-O-Fe site on the CuFe-C 3 N 4 was confirmed by in situ DRIFTS and 57 Fe Mössbauer spectroscopy. This Cu-O-Fe site was responsible for the improved catalyst performance. DFT calculations illustrated that at the Cu-O-Fe site, H 2 O 2 dissociated into two ·OH radicals instead of ·H and ·OOH radicals as it did at the Cu-O-Cu site. The ·OH radicals combined with the ·CH 3 radicals from the CH 4 molecules to form methanol. These findings provided valuable insights into the rational design of active sites on carbon nitride materials.