The deep oxidation of NO was realized by Sr multi-site doped g-C3N4 via photocatalytic method

The NO removal activity of g-C3N4 is limited by many shortcomings including the high recombination rate of photo-generated carriers and secondary pollution induced by incomplete oxidation. Here, we modified g-C3N4 using multi-site Sr-doping with simultaneous N atoms replacement, cavity padding, and intercalation. The NO removal experiments showed that multi-site doping of Sr improved the NO removal rate by 1.5 times. Meanwhile, the conversion rate of secondary pollution (NO2) decreased from 62.5% to 15.8%. The effects of doped Sr were different with different doping modes. All the doping modals of Sr could decrease the band gap of g-C3N4. Meanwhile, the Sr that intercalated in the interlayer of g-C3N4 could improve the transfer of photogenerated electrons; the Sr that replaced the N atoms could help the activation of O-2 to produce more O-center dot(2)-; the Sr padded in the cavity provides g-C3N4 with the ability to activate the H2O2 for the generation of a stronger oxidant ((OH)-O-center dot). The different doping modes complement each other and combine to realize efficient and deep NO removal.