Probing reaction pathways for H2O-mediated HCHO photooxidation at room temperature

• 作者: Weiwei Shao Xiaodong Li Xiaolong Zu Liang Liang Yang Pan Junfa Zhu Chengming Wang Yongfu Sun Yi Xie
• 来源期刊: 纳米研究（英文版）
• 年，卷（期）: 2021,（5）
• 所属期刊栏目: Research Articles
• 页码范围: 1471-1478
• 页数: 8页
• 语种: 英文

摘要

Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO,while the underlying photooxidation mechanism is still unclear,especially the exact role of H2O molecules.Herein,we utilize in-situ spectral techniques to unveil the H2O-mediated HCHO photooxidation mechanism.As an example,the synthetic defective Bi2WO6 ultrathin sheets realize high-rate HCHO photooxidation with the assistance of H2O at room temperature.In-situ electron paramagnetic resonance spectroscopy demonstrates the existence of-OH radicals,possibly stemmed from H2O oxidation by the photoexcited holes.Synchrotron-radiation vacuum ultraviolet photoionization mass spectroscopy and H218O isotope-labeling experiment directly evidence the formed ·OH radicals as the source of oxygen atoms,trigger HCHO photooxidation to produce CO2,while in-situ Fourier transform infrared spectroscopy discloses the HCOO* radical is the main photooxidation intermediate.Density-functional-theory calculations further reveal the ·OH formation process is the rate-limiting step,strongly verifying the critical role of H2O in promoting HCHO photooxidation.This work first clearly uncovers the H2O-mediated HCHO photooxidation mechanism,holding promise for high-efficiency indoor HCHO removal at ambient conditions.