Surface Partial-Charge-Tuned Enhancement of Catalytic Activity of Platinum Nanocatalysts for Toluene Oxidation

Abstract

The ability to tune the surface partial charge of noble metal catalysts at the nanoscale size dimension is essential for harnessing the activity of nanocatalysts in many important environmental catalytic reactions, such as hydrocarbon oxidations. We report herein a synthetic pathway to control the catalyst−support interactions and enable a surface partial-charge-tuned enhancement of the nanocatalytic activity using titania-supported Pt nanoparticles for oxidation of toluene as a model system. This pathway involved the onepot wet-chemical synthesis of TiO 2 -supported ultrasmall Pt nanoparticles (1−5 nm) with a controlled morphology and size. The catalysts showed greatly enhanced activities for toluene oxidation, exhibiting a strong dependence on the support morphology (e.g., nanopowders, nanowires, nanotubes, and mesoporous structures). The tunable partial negative charges on Pt were achieved by suppressing roughening of the support surface, favoring O 2 spillover from TiO 2 to Pt. In situ DRIFT data further reveal two parallel pathways responsible for oxidation of the methyl group and opening of the aromatic ring, the latter of which is favored by the partial negatively charged Pt, leading to a high activity. These findings provided insights into tuning nanoscale catalytic properties, which has significant implications for the design of supported noble metal nanocatalysts for environmental catalysis.

Efficient catalytic combustion of toluene at low temperature by tailoring surficial Pt0 and interfacial Pt-Al(OH)x species

“…The aromatic ring could be adsorbed on noble metal catalysts through π-binding ( Liu et al., 2019a ; Wang et al., 2018a ). Accordingly, toluene would be adsorbed via π-binding as the electron in d-orbital of the negatively charged Pt could back-donation to the π∗ of toluene ( Lu et al., 2019 ). Therefore, the adsorption interaction bond between toluene and the Pt/γ-Al 2 O 3 might be the π-binding.…”

Nanocage‐Shaped Co3−xZrxO4 Solid‐Solution Supports Loaded with Pt Nanoparticles as Effective Catalysts for the Enhancement of Toluene Oxidation

“…[ 36 ] The cationic Pt 2+ is suggested to result from Pt(acac) 2 not being fully reduced by ethylene glycol (EG), or the Pt nanoparticles are slightly oxidized if exposed to air during the synthesis steps. [ 18 ] Importantly, metallic Pt is the major Pt phase in the catalysts, which plays a role in the oxidation of toluene. Furthermore, the actual Zr/Co atomic molar ratio and Pt content were obtained by inductively coupled plasma atomic emission spectroscopy and are presented in Table 1.…”

“…The yPt/Co 3−x Zr x O 4 catalysts were successfully synthesized via chemically etching Cu 2 O nanocube templates, followed by thermal and impregnation treatments. [17][18][19] First, the clear and homogeneous nanocube morphology of Cu 2 O template can be observed by SEM, with an average diameter size of ≈650 nm (Figure 1a-d). After a solution-phase cation exchange method, reported elsewhere, [20] Co(OH) 2 and Zr x (OH) 4x /Co(OH) 2 nanosheets grew into hollow nanocages, as shown in Figures 1e,i, respectively.…”

Insights into the role of strontium in catalytic combustion of toluene over La1−xSrxCoO3 perovskite catalysts

“…S4 (ESI †), peaks around 1619 and 1495 cm À1 47 were assigned to the in-plane skeletal vibration of the aromatic ring. At the same time, the absorption intensity of benzaldehyde species (1593 and 1446 cm À1 ) and benzoate species (1533 cm À1 ), 47,48 and the asymmetric vibration (1563 cm À1 ) 49,50 and symmetric vibration (1391 cm À1 ) 51,52 infrared peaks attributed to the benzoate species increased with time, implying that toluene and intermediate product were easily adsorbed on both L 0.82 S 0.18 C and LC samples. The peak around 3078 cm À1 was assigned to the absorption of the benzene ring.…”