Facilitating Catalytic Purification of Auto-Exhaust Carbon Particles via the Fe₂O₃{113} Facet-dependent Effect in Pt/Fe₂O₃ Catalysts

Abstract

The purification efficiency of auto-exhaust carbon particles in the catalytic aftertreatment system of vehicle exhaust is strongly dependent on the interface nanostructure between the noble metal component and oxide supports. Herein, we have elaborately synthesized the catalysts (Pt/Fe2O3-R) of Pt nanoparticles decorated on the hexagonal bipyramid α-Fe2O3 nanocrystals with co-exposed twelve {113} and six {104} facets. The area ratios (R) of co-exposed {113} to {104} facets in α-Fe2O3 nanocrystals were adjusted by the fluoride ion concentration in the hydrothermal method. The strong Pt–Fe2O3{113} facet interaction boosts the formation of coordination unsaturated ferric sites for enhancing adsorption/activation of O2 and NO. Pt/Fe2O3-R catalysts exhibited the Fe2O3{113} facet-dependent performance during catalytic purification of soot particles in the presence of H2O. Among the catalysts, the Pt/Fe2O3-19 catalyst exhibits the highest catalytic activities (T 50 = 365 °C, TOF = 0.13 h–1), the lowest apparent activation energy (69 kJ mol–1), and excellent catalytic stability during soot purification. Combined with the results of characterizations and density functional theory calculations, the catalytic mechanism is proposed: the active sites located at the Pt–Fe2O3{113} interface can boost the key step of NO oxidation to NO2. The crystal facet engineering is an effective strategy to obtain efficient catalysts for soot purification in practical applications.

Functional MCFe@PTFE Filters for the Catalytic Oxidation of PCDD/Fs at Low Temperatures

“…The peak position of Fe 2p 3/2 was fitted into two peaks: the Fe 2+ valence state was characterized by Fe 2p 3/2 peak (BE = 710.9 eV), whereas the Fe 2p 3/2 signal at 714.1 eV was indicative of the presence of surface Fe 3+ . One peak located at around 718.4 eV is assigned to the satellite peak of Fe 2p 3/2 , which can prove the formation of Fe 3+ species at the surface of the catalysts . According to calculations, the ratio of Fe 3+ /Fe is 60.5% .…”

Study on the Catalytic Characteristics of Precious Metal Catalysts with Different Pt/Pd Ratios for Soot Combustion

“…The reaction mechanism of Nox-assisted soot oxidation has also been determined. Li 33 37 used this method to study the electrontransfer mechanism during the oxidation of soot. Wang 38 et al used the DFT method to prove that oxygen vacancies and alkali metals can promote the soot combustion activity of CeO 2 .…”

A room-temperature formaldehyde sensor based on hematite for breast cancer diagnosis

“…For example, Deng et al reported that the Fe 2 O 3 {113} facet interaction increased the density of the active oxygen species, further boosting the activation of O 2 and NO. 10 Similarly, hollow α-Fe 2 O 3 octadecahedra enclosed by the {113} and {104} facets were conducive to the generation of O-vacancy and surface OH species, resulting in high activity and stability of HCHO. 11 However, there have been a few studies and efforts in developing facet-enclosed α-Fe 2 O 3 -based HCHO gas-sensing devices at room temperature.…”