Facile Synthesis of Ag–CoOx Catalysts for 4-Nitrophenol Reduction

Abstract

A chemical reduction method was developed for the synthesis of silver-cobalt oxides (Ag–CoO_x). The structural and compositional properties of the as-prepared Ag–CoO_x were systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS). Benefiting from the synergistic effect between Ag and CoO_x, the Ag–CoO_x catalyst exhibited excellent catalytic activity and high cycling stability toward the reduction of 4-nitrophenol (4-NP). Kinetic studies of Ag₂–Co₃O_x revealed that the apparent rate constant (k_app) reached 63.18 × 10^–3 s^–1, which is superior to many previously reported Ag-based or Co-based catalysts for 4-NP reduction. Notably, after 5 consecutive catalytic cycles, the catalyst still maintained a conversion efficiency of over 97% for 4-NP. This work provides a promising synthetic route for high-quality nanoporous Ag–CoO_x, which is expected to promote their practical applications in catalysis and environmental sustainability.