Cation deviated stoichiometry Ca1.1ZrO3 perovskite as an efficient ozonation catalyst for m-cresol wastewater degradation

Highly efficient and stable catalysts for continuous catalytic ozonation of organic pollutants are of great significance in industrial applications. Perovskites have been seen as promising environmental catalysts because of their tunable defect structures and electronic properties. This work reports on A-site cation stoichiometry deviation as an effective engineering strategy to improve the crystallinity of perovskite CaZrO3, as well as its catalytic ozonation activity. High pure phase Ca1.1ZrO3 nanocrystals were successfully synthesized using a co-precipitation calcination method and evaluated as ozonation catalysts for m-cresol degradation. Surprisingly, Ca1.1ZrO3 exhibits a higher total organic carbon (TOC) removal rate, ozone utilization rate, and conversion rate of m-cresol than the stoichiometric of CaZrO3 and other conventional transition metal catalysts. In addition, Ca1.1ZrO3 shows an almost constant conversion rate of m-cresol (100%) and TOC removal rate (similar to 82%) during uninterrupted 100-h catalytic ozonation m-cresol degradation, demonstrating its excellent catalytic stability. These outstanding catalytic activity and stability toward ozonation are attributed to the synergistic meliorated oxygen octahedron structure, including Zr cation and contiguous coordinated oxygen, by introducing a non-stoichiometry defect into the perovskite. Thus, Ca1.1ZrO3 presents an advanced oxidation process of reactive oxygen species (.OH, O-2(.)- , O-1(2)). These results were verified by in situ X-ray diffraction, in situ Fourier transform infrared spectroscopy, electron paramagnetic resonance, and density functional theory. This work strongly believes that Ca1.1ZrO3 can be an efficient, stable, and an economic catalyst for catalytic ozonation.