Superoxide anion and singlet oxygen dominated faster photocatalytic elimination of nitric oxide over defective bismuth molybdates heterojunctions

Establishing an ideal photocatalytic system with efficient reactive oxygen species (ROS) generation has been regarded as the linchpin for realizing efficient nitric oxide (NO) removal and unveiling the ROSmediated mechanism. In this work, a novel oxygen-deficient 0D/1D Bi3.64Mo0.36O6.55/Bi2MoO6 heterojunctions (BMO-12-H) were successfully synthesized under the enlightenment of clarified crystal growth mechanism of bismuth molybdates. Because of the synergies between defect-engineering and heterojunction-construction, BMO-12-H demonstrated improved photoelectrochemical properties and O-2 adsorption capacity, which in turn facilitated the ROS generation and conversion. The enhancement of .O-2(-) and O-1(2) endowed BMO-12-H with strengthened NO removal efficiency (59%) with a rate constant of 12.6*10-2 min(-1). A conceivable NO removal mechanism dominated by center dot O-2(-) and (1)O(2 )was proposed and verified based on the theoretical calculations and in-situ infrared spectroscopy tests, where hazardous NO was oxidized following two different exothermic pathways: the center dot O2--induced NO -> NO3- process and the O-1(2)- induced NO-. NO2-. NO3- process. This work offers a basic guideline for accelerating ROS generation by integrating defect-engineering and heterojunction-construction, and provides new insights into the mechanism of efficient NO removal dominated by center dot O-2(-) and O-1(2).