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

[Display omitted] •Small Ni1−xMnxCo2O4 nanoparticles were synthesized by low-temperature gel combustion.•All the nanoparticles revealed strong catalytic performance in 4-nitrophenol reduction.•The catalytic performance of Ni0.5Mn0.5Co2O4 nanoparticles was superior to NiCo2O4 and MnCo2O4 nanoparticles.•>90 % of 4-nitrophenol could be reduced in 12 min.•The anomalous catalytic behaviors of the nanostructures in repeated cycles were explained. 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.