Probing reaction pathways for H2O2-mediated HCHO photooxidation at room temperature
mechanistic study, H2O-mediated, HCHO photooxidation, room temperature
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 H2O2 molecules. Herein, we utilize in-situ spectral techniques to unveil the H2O2-mediated HCHO photooxidation mechanism. As an example, the synthetic defective Bi2WO6 ultrathin sheets realize high-rate HCHO photooxidation with the assistance of H2O2 at room temperature. In-situ electron paramagnetic resonance spectroscopy demonstrates the existence of •OH radicals, possibly stemmed from H2O2 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 H2O2 in promoting HCHO photooxidation. This work first clearly uncovers the H2O2-mediated HCHO photooxidation mechanism, holding promise for high-efficiency indoor HCHO removal at ambient conditions.
Tsinghua University Press
Weiwei Shao, Xiaodong Li, Xiaolong Zu, Liang Liang, Yang Pan, Junfa Zhu, Chengming Wang, Yongfu Sun, Yi Xie. Probing reaction pathways for H2O2-mediated HCHO photooxidation at room temperature. Nano Research 2021, 14(5): 1471-1478.