Ce doped Bi-MOF derived hollow BiO/CeO: Abundant oxygen vacancies to efficiently enhance catalytic ozonation of 4-Nitrophenol.

4-Nitrophenol (4-NP), a toxic and persistent pollutant in chemical wastewater, presents significant challenges in degradation and mineralization. Conventional ozone oxidation catalysts are hindered by low efficiency, mass transfer constraints and metal leaching, necessitating the development of stable and efficient catalysts. Herein, BCn-H/MS, the derivative of Bi(Ce)-MOF, was prepared by in situ incorporation, thermal decomposition and acid etching. The resulting materials were characterized and employed in catalytic ozonation for the reduction of 4-NP. Under the specific experimental conditions of the O+BC0.3-H/MS system, the total organic carbon (TOC) and chemical oxygen demand (COD) removal rates of 4-NP were observed to reach 94.6 % and 91.8 % within 30 min, respectively. These two parameters were improved by raising the initial pH, reducing the pollutant concentration and increasing the catalyst dosage. The abundant oxygen vacancies (OVs) were regarded as the pivotal catalytic site of BC0.3-H/MS, which was conducive to the adsorption of O and the acceleration of the formation of reactive oxygen species (ROS). The regular hollow square structure effectively boosted the specific surface area, increased OVs exposure and accelerated the adsorption and mass transfer process. The electron paramagnetic resonance (EPR) results demonstrated that the primary ROS engaged in the degradation reaction were ⋅OH and ⋅O. BC0.3-H/MS demonstrated excellent stability and reusability in cyclic experiments. Toxicity analysis revealed that the O+BC0.3-H/MS system exhibited an effective detoxification effect. Ultimately, the primary degradation pathway of 4-NP was proposed through liquid chromatography-mass spectroscopy (LC-MS) and in-situ diffuse reflectance infrared fourier-transform spectroscopy (DRIFTS) analyses at varying reaction times.