Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences
Ruiyuan NIU;Dan-dan ZHU;Jun-ji CAO;Yu HUANG
Study found that secondary organic aerosols(SOA) have important contribution to the concentration of PM2.5 of typical heavy haze pollution in cities of our country ~. Nitrogen oxides(NOx) and volatile organic compounds(VOCs) are important precursors for formation of SOA. Therefore, taking effective measures and technologies to control concentration level of NOx and VOCs in the atmosphere has important practical significance to improve the air quality in our country. Fabrication of heterostructured photocatalysts has drawn significant interest in photocatalytic degradation of organic and inorganic pollutants because these catalysts can expand the light absorption range and promote the separation of photo-generated charge carriers ~. Most bismuth compounds with a layered structure show enhanced visible light absorption and efficient photocatalytic performance ~. Given the thermal instability of(BiO)_2CO_3 ~, we adopted in situ calcination to obtain Bi2O3/(BiO)_2CO_3 heterojunction. 2.5 mmol of Bi(NO_3)_3·5H_2O and 10 mmol of CO(NH_2)_2 were mixed and dissolved into 35 m L of deionized water. After vigorous agitation for 30 min at room temperature, the formed suspension liquid was transferred into a 50 m L Teflon-lined stainless steel autoclave and heated at 160 °C for 12 h. After naturally cooling the autoclave to room temperature, the white(BiO)_2CO_3 sample was collected, repeatedly washed with deionized water and absolute ethanol three times, and dried overnight at 70 °C. The as-prepared(BiO)_2CO_3 sample was further calcined at 400 °C for 1 h to obtain Bi_2O_3/(BiO)_2CO_3 composites. And the performance of the fabricated catalysts for NO removal was evaluated. Results showed that the as-prepared Bi_2O_3/(BiO)_2CO_3 exhibited significant visible light photocatalytic activity for NO removal(Figure 1a). The different photocatalytic results were attributed to the improved charge separation and light absorption range under solar light, as confirmed by UV-vis diffuse reflectance spectroscopy(DRS)(Figure 1b) and photocurrent data(Figure 1c). The heterojunction interface formed cannot only improve the charge separation of photo-induced electron–hole pairs but also broaden the light absorption range. Multiple runs of photocatalytic experiments showed that Bi_2O_3/(BiO)_2CO_3 was not significantly deactivated during long-term NO oxidation(Figure 1d). This result indicates that the BOC-based heterojunction is a stable photocatalyst with promising application in gaseous NOx abatement.