Enhanced MnO 2 nanorods to CO and volatile organic compounds oxidative activity by platinum nanoparticles

Abstract

Pure-phase α-MnO 2 and δ-MnO 2 nanorods were synthesized through an easy solution-based hydrothermal method. Platinum nanoparticles supported by the obtained MnO 2 nanorods were prepared by the colloid deposition process. The microstructure and adsorption activity of the obtained catalysts were researched by different techniques such as transmission electron microscopy (TEM), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), N 2 adsorption-desorption measurements, and H 2 temperature-programmed reduction (H 2-TPR). The cataluminescence (CTL) properties of CO and volatile organic compounds (VOCs), such as benzene and toluene, on the resultant catalysts were explored. The results showed that the platinum nanoparticles were well distributed in α-MnO 2 and δ-MnO 2. In addition, the Pt load process does not affect the crystal phase structure of the α-MnO 2 nanorods, but can generate structural changes in the δ-MnO 2 nanorods. The phase transformation did not the result of the reaction between the δ-MnO 2 nanorods and Pt as shown in the XPS study. The α-MnO 2 and δ-MnO 2 nanorods showed a high catalytic oxidative activity toward CO, benzene, and toluene, and δ-MnO 2 showed a higher activity than the α-MnO 2 phase. Although, the Pt load led to a decrease in the surface area of the MnO 2 nanorods which was confirmed by the N 2 adsorption-desorption measurements, but the H 2-TPR results showed that the interaction between Pt and MnO 2 was intense, which significantly enhanced its catalytic activity. The Pt/δ-MnO 2 nanorods exhibited a higher activity than Pt/α-MnO 2. CTL research showed that the activities of the four catalysts increased in the order of α-MnO 2≤ δ-MnO 2