The purified molybdenite were obtained using concentrated sulfuric acid and heating oxidation method, and the samples before and after oxidation were characterized systematically based on X-ray fluorescence spectrum (XRF), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectroscopy. Moreover, its electrocatalytic properties were tested and analyzed. The results show that the average grain size of MoS₂ (002) crystal plane direction decreases by 14% and interlayer spacing increases 0.04Å after concentrated sulfuric acid oxidation, and S²⁻ is oxidized into S⁶⁺, indicating that layers of Molybdenite can be stripped through oxidation. The reductive peak of potential move forward after oxidation, implying reduction enhancement on p-nitrophenol.