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

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.