This study focuses on the chemical synthesis of high-purity silica derived from Algerian diatomite, targeting its use in advanced technological applications, particularly in the photovoltaic sector. Diatomite, a naturally abundant siliceous mineral, was subjected to a controlled chemical purification process using a 4 mol/L sodium hydroxide (NaOH) solution. This alkaline leaching aims to dissolve impurities, enhance silica content, and improve the material's structural order. The treated samples were extensively characterized by X-ray diffraction (XRD), to assess crystallinity and phase evolution, and X-ray photoelectron spectroscopy (XPS), to examine surface chemistry and impurity levels. The untreated diatomite contained approximately 80% SiO₂. Post-treatment, XRD patterns indicated a clear improvement in crystallinity and the removal of amorphous or non-siliceous phases. XPS analysis revealed a marked reduction in surface impurities, particularly metallic elements and carbon-containing species, with a significant drop in carbon peak intensity, indicating a cleaner silica surface. This enhanced surface purity is crucial for the downstream production of solar-grade silicon. Overall, the results confirm that sodium hydroxide NaOH-based chemical treatment is a simple, effective, and scalable approach for producing high-purity silica from natural diatomite. The purified material demonstrates excellent potential for use in the photovoltaic industry and other advanced applications requiring ultra-clean silica sources.