Fabrication of three-dimensional hierarchical porous 2D/0D/2D g-C3N4 modified MXene-derived TiO2@C: Synergy effect of photocatalysis and H2O2 oxidation in NO removal

Abstract

A novel three-dimensional multi-level porous g-C₃N₄ modified MXene-derived TiO₂@C aerogel (g-C₃N₄/TiO₂@C aerogel) was synthesized for NO removal. Through SEM analysis, 2D g-C₃N₄ and 2D Ti₃C₂ nanosheets were constructed into an interconnected macroscopic framework with continuous macropores via ice template. OD TiO₂ nanoparticles uniformly covered 2D C nanosheets with irregular mesopores and macropores in in-situ oxidation of Ti₃C₂ nanosheets by calcination via TEM analysis. g-C₃N₄/TiO₂@C aerogel for photocatalytic activation of hydrogen peroxide (H₂O₂) had an excellent efficiency of 90.7% for NO removal at parts per million level. This efficiency was 4.9 times and 7.8 times that of g-C₃N₄/TiO₂@C aerogel and H₂O₂ individually, due to the synergy between photocatalysis and H₂O₂ oxidation. Meantime, g-C₃N₄/TiO₂@C aerogel exhibited an enhanced performance compared with g-C₃N₄ nanosheet (55.7%) and TiO₂@C aerogel (38.5%). It was attributed to the large specific surface area (93.82 m²/g) with hierarchical mesoporous and macroporous structure and the 2D/OD/2D heterojunction of g-C₃N₄/TiO₂@C aerogel, further enhancing electron-hole separation. The mechanism was hypothesized that g-C₃N₄/TiO₂@C aerogel activated H₂O₂ to generate hydroxyl radicals (·OH) and superoxide radicals (·O₂^-) for oxidation of NO.

Keywords: Nitrogen oxides; Photocatalytic; Synergy effect; TiO(2)@C; g-C(3)N(4) aerogel.