Robust magnetic laccase-mimicking nanozyme for oxidizing o-phenylenediamine and removing phenolic pollutants

In this study, we report a novel magnetic biomimetic nanozyme (Fe3O4@Cu/GMP (guanosine 5'-monophosphate)) with high laccase-like activity, which could oxidize toxic o-phenylenediamine (OPD) and remove phenolic compounds. The magnetic laccase-like nanozyme was readily obtained via complexed Cu2+ and GMP that grew on the surface of magnetic Fe3O4 nanoparticles. The prepared Fe3O4@Cu/GMP catalyst could be magnetically recycled for at least five cycles while still retaining above 70% activity. As a laccase mimic, Fe3O4@Cu/GMP had more activity and robust stability than natural laccase for the oxidization of OPD. Fe3O4@Cu/GMP retained about 90% residual activity at 90°C and showed little change at pH 3-9, and the nanozyme kept its excellent activity after long-term storage. Meanwhile, Fe3O4@Cu/GMP had better activity for removing phenolic compounds, and the removal of naphthol was more than 95%. Consequently, the proposed Fe3O4@Cu/GMP nanozyme shows potential for use as a robust catalyst for applications in environmental remediation.