Fumed Silica-Derived CoOx@SiO2 Composites for Catalytic Reduction of 2-Nitrophenol

Nitrophenols, despite their wide synthetic utility in the specialty chemical industry, are recognized as toxic and can pose a serious environmental hazard. A popular strategy for the purification of wastewater containing nitrophenols is their catalytic reduction to the corresponding aminophenols in the presence of supported transition metal catalysts. However, the practical application of such systems is hindered by tedious catalyst manufacturing protocols and strong dependence on the catalyst/support microstructure. Herein, a series of CoOx@SiO2 composites was prepared by a direct reduction of aqueous solutions of Co(II) salts (Co(OAc)2, CoCl2, and CoF2) with fumed silica having a triethoxysilane-modified surface. The prepared composites, despite the observed low cobalt content (0.1–0.2 wt%), proved highly effective in reducing 2-nitrophenol to 2-aminophenol, demonstrating a cost-effective, readily available non-precious-metal-based system for the remediation of nitrophenols from contaminated water.