High efficiency photocatalytic degradation of indoor formaldehyde by Ag/g-C3N4/TiO2 composite catalyst with ZSM-5 as the carrier

Indoor formaldehyde is an invisible killer of human health. Photocatalytic method can remove formaldehyde with high efficiency and no pollution. Ag/ZSM-5/g-C3N4/TiO2 catalyst was prepared by simple calcination and silver reduction method. The degradation efficiency of Ag/g-C3N4/TiO2 and Ag/ZSM-5/g-C3N4/TiO2 catalysts reached 84.71% and 93.53%, respectively. The activity of composite catalyst is 2.65 times and 1.22 times of pure semiconductor g-C3N4 and TiO2. Silver nanoparticles can act as an electron trap and broaden the photoresponse range of the catalyst under the influence of surface plasmon resonance, which makes the composite catalyst receive more excitation energy in the visible range. As a catalyst carrier, ZSM-5 (SiO2/Al2O3) zeolite plays the role of supporting and dispersing catalysts. In addition, ZSM-5 zeolite can absorb a large number of formaldehyde molecules to promote the physical process of photocatalytic reaction. Ion chromatography revealed that HCOOH was an intermediate product in the process of formaldehyde oxidation, and •O2−, •OH were the main active groups. Cycle experiment shows that the photocatalytic stability of the composite catalyst is improved after the addition of ZSM-5 zeolite. The catalyst is cheap and easy to be obtained and the operation is simple and feasible, which can lay a certain foundation for future research. [Display omitted] •The composite catalyst Ag/ZSM-5/g-C3N4/TiO2 was synthesized.•The degradation rate of Ag/ZSM-5/g-C3N4/TiO2 to formaldehyde reached 93.53%.•ZSM-5 promotes the physical adsorption process of photocatalytic reaction.•Heterojunction and localized surface plasmon resonance effect (LSPR) are beneficial to reactions.