Research progress on nano-photocatalytic removal of atmospheric NOx in the global environment

[ Instrument network instrument research and development ] Recently, Huang Yu, a researcher at the Institute of Earth Environment of the Chinese Academy of Sciences, cooperated with Xi’an Jiaotong University, Shaanxi Normal University, etc., to develop new nano-photocatalytic materials with controllable preparation, efficient separation of photogenerated carriers, and identification of catalytic reaction processes. Research on the interface reaction mechanism has achieved a series of results.

Using the method of in-situ synthesis, the research team can control to prepare a Z-type α-Bi2O3/CuBi2O4 heterojunction with high-quality interface contact and strong redox capability. The DFT calculation results show that 3.6e electrons are transferred from α-Bi2O3 to CuBi2O4 after the two composites form the interface structure. The photocurrent and fluorescence results further show that the Z-heterojunction α-Bi2O3/CuBi2O4 interface has a significant promotion effect on the separation and transport of photogenerated carriers. The results of the activity test showed that after α-Bi2O3 and CuBi2O4 are constructed into a Z-type heterojunction, the visible light removal efficiency of NO can be increased by 1.8 times by promoting the separation and transmission efficiency of photo-generated carriers.

Using the method of in-situ surface reduction, the research team can control the preparation of Bi-BiPO4 (BPO) composite nano-photocatalytic material, which promotes the adsorption and activation of O2 and the generation of active free radicals during the catalytic reaction. Compared with BPO, which has almost no visible light activity, Bi-BPO can remove 32.8% of NO and maintain good stability. The La-doped Bi5O7I (AL-BOI) microspheres supported by Au nanoparticles can be prepared in a controlled manner, which enhances the light absorption capacity of L-BOI in the visible light region, while the doping of La forms a large number of oxygen vacancies on the BOI surface, effectively enhancing This improves the removal efficiency of NO and simultaneously suppresses the formation of NO2, a toxic by-product. Using the up-conversion properties of carbon quantum dots (CQDs), the research team can control the preparation of CQDs/ZIF-8 composite materials. The experimental results show that the introduction of CODs can broaden the light absorption range of the material to the entire visible light region on the one hand, and on the other hand significantly enhance the electron separation efficiency of ZIF-8, thereby achieving efficient removal of NO. By doping with N elements to strengthen the up-conversion characteristics of carbon quantum dots, the research team can control the preparation of N/CQDs-MIL-125(Ti) composite materials. The results of in-situ infrared spectroscopy showed that the N/CQDs loaded MIL-125(Ti) had a conversion process from Ti4+-NO to Ti3+-NO during the photoreaction stage (Figure 5), which is the key to the suppression of NO2 by-product.

Related research provides effective control strategies for the construction of nano-photocatalytic air purification materials with high visible light catalytic activity and high NO selectivity.