Maximizing the Formation of Reactive Oxygen Species for Deep Oxidation of NO via Manipulating the Oxygen-Vacancy Defect Position on (BiO)₂CO₃

Constructing oxygen vacancies (OVs) in metal-oxide semiconductors is an effective and simple way to enhance the photocatalytic performance via promoting the utilization of solar light and boosting the formation of surface reactive oxygen species (ROS). The presence of different oxygen atoms in the same crystal structure can possibly lead to the formation of different types of OVs with distinct physicochemical and optoelectronic properties. Particularly, the two different crystallographic positions of oxygen atoms in the [BiO]22+ layer of (BiO)2CO3 (BOC) allow the construction of two types of OVs (OVs1 and OVs2). In this work, OVs1-BOC and OVs2-BOC are synthesized via introducing the OVs1 and OVs2 on the surface of the BOC. The influence of OVs1 and OVs2 on the generation of ROS in the BOC is demonstrated based on theoretical and experimental studies by analyzing the separation and redox potentials of photogenerated charge carriers, absorption surface adsorbates (H2O and O2), and reaction active energy. The photocatalytic performance is evaluated by photo-oxidative nitric oxide (NO) removal efficiency under visible light irradiation. The OVs1-BOC and OVs2-BOC exhibit 50.0 and 41.6% photo-oxidative NO removal efficiencies, while generating 15.6 and 16.54 ppb NO2, respectively. The in situ Fourier transform infrared spectroscopy and estimated NO conversion pathway reveal the photo-oxidative NO removal mechanism and suppression of NO2 formation on the surfaces of OVs1-BOC and OVs2-BOC. This work demonstrates a straightforward approach for enhancing the photo-oxidative NO removal via manipulating the OV defect position in semiconductors.