Interface effect of mixed phase Pt/ZrO2 catalysts for HCHO oxidation at ambient temperature

Abstract

A series of high-efficiency Pt/ZrO₂ catalysts were successfully prepared by simple methods on the basis of a ZrO₂ support with a mixed monoclinic/tetragonal phase structure. The activity test results showed that the mixed phase catalysts exhibited higher catalytic activity than the pure monoclinic phase, and HCHO can be completely oxidized into CO₂ and H₂O at near ambient temperature. XRD, Raman and HRTEM results demonstrated that the monoclinic–tetragonal phase interface with abundant defects was formed due to the introduction of the tetragonal phase. According to the results of TEM, XPS and H₂-TPR, the mixed phase interfacial structure can induce the formation of the active oxygen species, ionic Pt^δ+ species, strong metal-support interaction and low-temperature reducibility, which was vital for the significant improvement of the catalytic activity. Furthermore, the specific HCHO reaction rate of the catalysts at 55 °C increased from 0.8 × 10⁻³ to 10.4 × 10⁻³ mmol h⁻¹ m⁻² and the activation energy decreased remarkably from 213.5 to 24.7 kJ mol⁻¹ with the increase of the biphase interface content. In situ DRIFTS spectra showed that the special interfacial structure can change the reaction pathway of HCHO oxidation and inhibit the formation of inert carbonate species, thus greatly enhancing the HCHO oxidation activity.