Insight into singlet oxygen generation from metastable lattice of Treated-NaBiO3: A mechanism study

Abstract

Nitric acid treated NaBiO3 (N-NBO) was observed to have the ability of yielding singlet oxygen (1O2) for degrading organic pollutants, and a mechanism study or insight into 1O2 generation from metastable lattice of treated-NBO was conducted. It was demonstrated that the acid treatment made Bi(V)O6 octahedron in NBO undergo drastic distortion, leading to the formation of a metastable Bi(III)O6 octahedron, which could store and release active oxygen as 1O2. As confirmed by characterization experiments, the 1O2-generating ability of N-NBO could be activated, deactivated and re-activated by different treatments, which corresponded to the formation, consummation and re-formation of the active metastable Bi(III)O6 octahedron. The formation of the metastable structure was related closely to the conversion of Bi5+ to Bi3+ in N-NBO, and its “collapse” eliminated the activity of the metastable Bi(III)O6 octahedron “pseudo-interface”. This structure was responsible for the release of active oxygen from the lattice in the form of 1O2, and the deactivated N-NBO could be re-activated by re-constructing this metastable structure through metal-ion doping and iodide reduction. A mechanism of 1O2 generation was proposed by considering the Bi(V)-Bi(III) conversion and the formation of the metastable Bi(III)O6 octahedron.