High-entropy antiperovskite metal nitrides with nitrogen vacancies as magnetic sonocatalysts for ciprofloxacin degradation

The continuing usage of antibiotics such as ciprofloxacin (CIP) in our water systems raises significant concerns for both the environment and public health. Traditional methods for treating wastewater frequently fall short in completely removing contaminants, highlighting the necessity for more advanced catalytic solutions. This study offers a CrFeCoNiZn high-entropy metal nitride (HEMN) magnetic sonocatalyst that has been thoughtfully engineered with nitrogen vacancies (NVs). The synthesis process involved hydrothermal treatment followed by ammonia nitridation and hydrogenation. The HEMN catalyst from optimized condition, HEMN600A, showcases a single-phase cubic anti-perovskite structure, containing a uniform distribution of Cr, Fe, Co, Ni, Zn, and N. The structure has been confirmed using various analyses, including XRD, XPS, SEM, and XAS. The presence of NVs increases the electron density surrounding metal centers, alters the d-band center, and greatly enhances the generation of reactive oxygen species (ROS) when exposed to ultrasonic irradiation. Consequently, HEMN600A successfully degraded 93% of CIP in 15 minutes. Additionally, HEMN600A shows improved magnetization, making it easier to recover magnetically, while also maintaining stable performance through several reuse cycles. Studies involving radical scavengers and mass spectrometry provide additional confirmation of the degradation pathways mediated by reactive oxygen species. This study shows NVs-engineered HEMNs as novel and magnetically recoverable sonocatalysts, offering a sustainable solution for the removal of antibiotics in water treatment. • N-vacancy engineered CrFeCoNiZn HEMN synthesized for sonocatalysis. • HEMN600A degraded 93% of ciprofloxacin in 15 min. • Nitrogen vacancies enhance ROS generation and magnetic recovery.