Rapid nitrophenol degradation using gel-combustion synthesized nickel/manganese cobaltite (Ni1−xMnxCo2O4) nanoparticles

Abstract

Developing efficient catalysts is one of the challenging tasks for protecting our environment from contamination. Here we present the synthesis of Ni1−xMnxCo2O4, noble-metal free multimetallic oxide nanoparticles of 9.5–25.0 nm average sizes by a low-temperature gel combustion method and their utilization as catalysts for rapid reduction of 4-nitrophenol (4-NP) to aminophenol (AP). Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and vibrating sample magnetometry were used for the characterization of the nanostructures. All the nanostructures revealed strong catalytic performance in the reduction of 4-NP, and the performance of Ni0.5Mn0.5Co2O4 nanoparticles was superior (>90 % reduction in 12 min) to that of NiCo2O4 and MnCo2O4 nanoparticles. While the 4-NP reduction process followed a pseudo-first-order kinetics for all the catalysts, the reduction efficiency of the samples manifested a complex trend from cycle to cycle. The anomalous catalytic behavior of the nanostructures in 4-NP degradation has been explained.