Operando Investigation of Toluene Oxidation over 1D Pt@CeO₂ Derived from Pt Cluster-Containing MOF

Abstract

A unique 1D nanostructure of Pt@CeO 2 −BDC was prepared from Pt@CeBDC MOF. The Pt@CeO 2 −BDC was rich in oxygen vacancies (i.e., XPS O β /(O α + O β ) = 39.4%), and on the catalyst, the 2 nm Pt clusters were uniformly deposited on the 1D mesoporous polycrystalline CeO 2 . Toluene oxidation was conducted in a spectroscopic operando Raman−online FTIR reactor to elucidate the reaction mechanism and establish the structure−activity relationship. The reaction proceeds as follows: (I) adsorption of toluene as benzoate intermediates on Pt@CeO 2 −BDC at low temperature by reaction with surface peroxide species; (II) reaction activation and ring-opening involving lattice oxygen with a concomitant change in defect densities indicative of surface rearrangement; (III) complete oxidation to CO 2 and H 2 O by lattice oxygen and reoxidation of the reduced ceria with consumption of adsorbed oxygen species. The Pt clusters, which mainly exist as Pt 2+ with minor amounts of Pt 0 and Pt 4+ on the surface, facilitated the adsorption and reaction activation. The Pt-CeO 2 interface generates reduced ceria sites forming nearby adsorbed peroxide at low temperature that oxidize toluene into benzoate species by a Langmuir−Hinshelwood mechanism. As the reaction temperature increases, the role of lattice oxygen becomes important, producing CO 2 and H 2 O mainly by the Mars-van Krevelen mechanism.

Multifunctional Graphdiyne–Cerium Oxide Nanozymes Facilitate MicroRNA Delivery and Attenuate Tumor Hypoxia for Highly Efficient Radiotherapy of Esophageal Cancer

“…Moreover, the X‐ray powder diffraction pattern indicated that the as‐synthesized CeO 2 NPs exhibited a series of characteristic peaks that correspond to a typical cubic fluorite CeO 2 crystal phase (JCPDS No. 43‐1002), [ 16 ] illustrating that well‐crystallized CeO 2 nanocrystals were successfully grafted onto GDY and maintained the same crystal structures as free CeO 2 (Figure 1E). We confirmed the elemental compositions of GDY and GDY–CeO 2 by X‐ray energy‐dispersive spectroscopy and X‐ray photoelectron spectroscopy (XPS) (Figure 1D–F and Figure S1F–H (Supporting Information)).…”

Construction of a Nanorod Structure‐Confined Pt@CeO2 Catalyst by an In‐Situ Encapsulation Strategy for Low‐Temperature Catalytic Oxidation of Toluene

“…It can be proved that there were two forms of Pt nanoparticles: in‐situ synthesis and conventional supported, which were consistent with the expectation. The synthesis method may hinder the growth of the active Pt NPs on CeO 2 support, thus affecting their catalytic activity [40] …”

“…The synthesis method may hinder the growth of the active Pt NPs on CeO 2 support, thus affecting their catalytic activity. [40] 2.2. Microstructure analysis XRD patterns of three catalysts were shown in Figure 3a, in which the normative diffraction peak (JCPDS No.34-0394) of cerium oxide with face-centered cubic structure can be observed.…”

In Situ Modulation of A‐Site Vacancies in LaMnO3.15 Perovskite for Surface Lattice Oxygen Activation and Boosted Redox Reactions

“…Since gaseous O 2 was absent during temperature ramp, the generation of the broad CO 2 peaks is from the oxidation of adsorbed toluene by activated surface O latt without the participation of gaseous O 2 . Furthermore, inspired by the recent study of toluene oxidation on Pt/CeO 2 by Yeung and co‐workers, [7] we plotted the relationship between mass reaction rates of toluene and the amount of surface O latt (D R ), and detected a linear relationship between the two parameters (Figure 5 c). The participation of activated surface O latt to boost toluene complete oxidation over xU‐LMO can be tentatively interpreted as follows.…”

“…Employing on‐line electrochemical mass spectrometry, Shao‐Horn and co‐workers [6] studied the evolution of O 2 in oxygen evolution reaction (OER) over 18 O‐labeled La 0.5 Sr 0.5 CoO 3− δ , and confirmed the involvement of surface lattice oxygen (O latt ). Using in situ operando Raman, Wang et al [7] . demonstrated that both the ring opening and deep oxidation of toluene to CO 2 over Pt/CeO 2 catalyst involved the participation of surface O latt .…”