Efficient photocatalysis of organic vapors using graphitic carbon nitride and iron dual-coupled ZnO nanocomposites

Abstract

Abstract This study assessed the performance of graphitic carbon nitride (g-C 3 N 4 ) and iron (Fe) dual-coupled zinc oxide (ZnO) nanocomposites (FCZs) in the photocatalytic degradation of vaporous β -pinene and o -xylene via a continuous system. The properties of the synthesized photocatalysts were examined by various spectral analyses. The adsorption efficiencies of g-C 3 N 4 -coupled ZnO composites (CZs) determined in the dark were lower than those of ZnO. In contrast, the CZ samples exhibited higher photocatalytic degradation than ZnO. Moreover, the photocatalytic degradation efficiencies of the FCZ photocatalysts were higher than those of the CZ, Fe-modified ZnO, and bare ZnO samples, likely due to the greater charge separation efficiency in FCZ. The optimal g-C 3 N 4 /ZnO and Fe/CZ ratios for the synthesis of the CZ and FCZ samples, respectively, were determined. Under certain conditions, mineralization efficiencies of β -pinene (37.0%) and o -xylene (46.6%) over an FCZ sample with the Fe/CZ ratio of 0.05 were lower than the corresponding photocatalytic degradation efficiencies (67.5% and 72.4%, respectively). CO and organic vapors were identified as the major gaseous intermediates, while chemicals adsorbed onto the catalyst surface inside the reactor were not detectable. Super oxide ion radicals, hydroxyl radicals, and positive holes appeared to be responsible for vapor degradation over the FCZ photocatalysts, and a heterojunction-type mechanism is proposed.