Synthesis of SiO2@MnCo2O4 core-shell nanorattles using layered double hydroxide precursors and studies on their peroxidase-like activity

The current work demonstrates a simple soft chemical approach to synthesize SiO2@MnCo2O4 core-shell nanorattles using SiO2@MnCo-LDH (layered double hydroxide) precursors. XRD analysis indicates the formation of MnCo2O4 nanoparticles (NPs) on SiO2 spheres. FESEM images show hierarchical flower-like MnCo2O4 NPs on the surface of the SiO2 spheres. TEM micrographs show the interstitial space between the core (SiO2) and the shell (MnCo2O4), indicating the core-shell nanorattle morphology of SiO2@MnCo2O4. BET adsorption-desorption isotherms of the SiO2@MnCo2O4 core-shell nanorattles indicate their mesoporous nature with high surface area. Optical studies indicate O2- -> Mn2+ and O2- -> Co3+ charge-transfer transitions and d-d transition in pure MnCo2O4 NPs and the SiO2@MnCo2O4 core-shell nanorattles. XPS measurements indicate the presence of Si4+, Mn2+, Co2+, Mn3+, Co3+, and O2- in the SiO2@MnCo2O4 core-shell nanorattles. The SiO2@MnCo2O4 core-shell nanorattles show paramagnetic and superparamagnetic behavior at 300 K and 5 K, respectively. After characterization, the SiO2@MnCo2O4 core-shell nanorattles were explored for peroxidase-like activity for the first time. The SiO2@MnCo2O4 core-shell nanorattles act as a peroxidase nanozyme and exhibit better peroxidase-like activity than pure MnCo2O4 NPs and horseradish peroxidase.