One-step synthesis of Ag-loaded Co3O4 as an efficient catalyst for the reduction of p-nitrophenol

Abstract

The composite comprised of noble metal and non-precious metal oxide as a catalyst offers both low cost and high performance. To obtain this structure, a two-step approach is usually performed, which is time and energy consuming. In this paper, a one-step hydrothermal method was proposed to prepare the Ag/Co3O4 composites with variable silver loadings, using cobalt acetate, silver nitrate, and l-arginine as the reductant. The catalytic activities of these Ag/Co3O4 composites were investigated taking p-nitrophenol (PNP) reduction using NaBH4 as the reducing agent. The results demonstrated that the Ag/Co3O4 composite exhibited superb catalytic reduction capacity towards PNP benefiting from the even dispersion of elemental Ag particles on the surface of Co3O4 microspheres. A reduction ratio of 89.33 % and a reaction rate of 0.1558 min−1 for PNP were obtained within 15 min under the optimal reaction conditions: Ag0.008/Co3O4 amount of 0.01 g·L−1, NaBH4 dosage of 7 mmol·L−1, PNP concentration of 0.108 mmol·L−1, a total reaction volume of 1000 mL and a temperature of 25 °C. Besides, the composite showed stable catalytic performance after five continuous uses, maintaining a PNP reduction rate above 82 %. This work presents an effective way for the facile preparation of noble metal-loaded composite catalysts.