Enhanced gas-phase photocatalytic removal of aromatics over direct Z-scheme-dictated H3PW12O40/g-C3N4 film-coated optical fibers

Abstract

Environmentally benign photocatalytic oxidation is one of the most promising approaches to remove volatile, highly toxic and refractory aromatics, and the key points of gas-phase photocatalytic oxidation of aromatics are to develop efficient photocatalysts and design suitable photoreactors. Here, the custom-designed H3PW12O40/g-C3N4 film-coated optical fiber photoreactor is demonstrated for gas-phase simulated sunlight photocatalytic removal of aromatics including benzene, toluene and m-xylene. At relative humidity of 73% and air atmosphere, the H3PW12O40/g-C3N4 film-coated optical fibers with H3PW12O40 doping level of 3.2% exhibit remarkably higher photocatalytic removal efficiency of benzene, toluene and m-xylene than that of the g-C3N4 film, and apparent rate constant of the H3PW12O40/g-C3N4 film for benzene, toluene and m-xylene removal is 2.42, 1.75 and 3.67 times higher than that of g-C3N4 film. The enhanced photocatalytic activity of the H3PW12O40/g-C3N4 film is ascribed to direct Z-scheme-dictated charge carrier migration mechanism, imparting not only superior photogenerated charge carrier separation ability but also undiminished redox capability of the photogenerated electrons and holes; additionally, the increased contact area of catalyst film with the substrates and improved light harvesting ability give rise to the important contribution to gas-phase photocatalytic removal of aromatics. Moreover, the catalyst film exhibits excellent adhesion, stability and recyclability, and the activity loss is negligible after total thirty times’ catalytic runs.