Constructing Z-scheme heterojunction of AC@g-C3N4/MnOx for effective removal of acetaldehyde in building environment

Abstract

Acetaldehyde is a major odorous compound that reduces perceived indoor air quality; consequently, a high-performance acetaldehyde purification material to facilitate its removal is required. In this study, a novel photocatalyst with a Z-scheme heterojunction of AC@g-C₃N₄/MnO_x (ACNMO) is proposed for efficient removal of acetaldehyde. The acetaldehyde removal efficiency of the AC_12.5 %@g-C₃N₄/MnO_x photocatalyst reached 91.9 % at an acetaldehyde concentration of 3.5 mg/m³, which was more effective than that of g-C₃N₄ (62.5 %). Owing to the Z-scheme heterojunction mechanism, the photoexcited electrons had stronger reducing properties, which in turn produced more $·O_2^{-}$, significantly improving the acetaldehyde removal performance. In terms of the long-term performance, the acetaldehyde removal of AC_{12.5 %}@g-C₃N₄/MnO_x (PA) remained near 90.5 % after 24 h in continuous flow. The byproducts of the photocatalytic reaction did not show significant increase during the reaction, and the characteristic peaks of the samples remained almost unchanged after reaction. In addition, the ACNMO material showed the best realistic odor removal performance in terms of both the subjective odor perception and objective VOCs concentration reduction. The results show that the novel AC@g-C₃N₄/MnO_x material for removing gaseous acetaldehyde has the advantages of a long lifespan, no byproducts, and stable chemical properties. This study provides a novel route for the selective removal of acetaldehyde at low concentrations.