Pt-Modulated CuMnOx Nanosheets as Catalysts for Toluene Oxidation

Abstract

Controllable ternary Pt–Cu–Mn lamellar oxides with different amounts of Pt were synthesized using a facile and expeditious self-propagating flaming technique for catalytic oxidation of toluene. The surface structure, composition, and structure–performance relationship were investigated by combining X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, scanning electron microscopy (SEM), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The catalytic performance of the as-produced catalysts toward the catalytic oxidation of toluene was investigated. Among the catalysts, the 0.5Pt-MnCu catalyst has shown 90% toluene removal at 228 °C with excellent cyclic stability, which is a significant achievement for MnCu binary nanosheet-like catalysts containing low amounts of Pt (0.5 wt %). This study has also inferred the degradation activity of modulated MnCu composite catalysts, which greatly hinges on the doping level of Pt. The lattice oxygen species are dominating according to the Mn–O bond strength, local environment, and reducibility. Moreover, Pt can increase the covalency of surface metal–oxygen bonds and electron affinity of surface metal-coordinated oxygen centers, thereby expediting the adsorption/activation of the gaseous oxygen molecules on oxide surfaces, which can step up the lattice oxygen as well as oxygen vacancy-involved reactions to invoke the Mars–van Krevelen and Langmuir–Hinshelwood mechanisms for boosting the overall toluene oxidation performance of PtCuMnOx catalytic materials. Based on the obtained results, this study proposes a vital insight into manipulating the nanoscale catalytic functions, which could also promise pivotal potential toward engineering the state-of-the-art transition-metal nanostructure for environmental catalysis.