NiFeS2 Nanozymes Derived From Ni-Fe Layered Double Hydroxide Precursor Using Thermal Decomposition Method: A Study on Their Peroxidase-Mimicking Properties.

In the present work, NiFeS2 nanoparticles were synthesized using NiFe-LDH (layered double hydroxide) as a precursor via a thermal decomposition method. The NiFe-LDH was converted into NiFeS2 nanoparticles at 200°C in diphenyl ether or 1-octadecene using two different sulfur sources (thioacetamide and thiourea). The formation of pure pyrite phase of NiFeS2 nanoparticles was proved by powder X-ray diffraction, while transmission electron microscopy (TEM) studies revealed nearly spherical, and well-dispersed NiFeS2 nanoparticles. X-ray photoelectron spectroscopy proved the presence of Ni2+, Ni3+, Fe3+, and S2 2- in the NiFeS2 nanoparticles. Optical characterization, using UV-vis diffuse reflectance spectroscopy, revealed that the NiFeS2 nanoparticles possess a narrow band gap (1.30-1.46 eV). The magnetic properties of NiFeS2 nanoparticles reveal paramagnetic behavior at 300 K and weak ferromagnetic characteristics at 5 K. Notably, the NiFeS2 nanoparticles exhibit intrinsic peroxidase-like activity. Under the experimental conditions employed in the present study, the NiFeS2 nanoparticles show enhanced catalytic efficiency compared to natural HRP and reported analogous nanozymes. Among the synthesized NiFeS2 nanoparticles, the NFS-DPE-TAA exhibits superior catalytic activity and demonstrates its applicability as a nanozyme-based colorimetric probe for H2O2 sensing.