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. 2020 Feb 26;11(1):1062.
doi: 10.1038/s41467-020-14816-w.

Activating low-temperature diesel oxidation by single-atom Pt on TiO2 nanowire array

Son Hoang #  1 , Yanbing Guo #  1   2 , Andrew J Binder  3 , Wenxiang Tang  1 , Sibo Wang  1 , Jingyue Jimmy Liu  4 , Huan Tran  1 , Xingxu Lu  1 , Yu Wang  5 , Yong Ding  6 , Eleni A Kyriakidou  3 , Ji Yang  2 , Todd J Toops  3 , Thomas R Pauly  7 , Rampi Ramprasad  1 , Pu-Xian Gao  8
Affiliations

Activating low-temperature diesel oxidation by single-atom Pt on TiO2 nanowire array

Son Hoang et al. Nat Commun. .

Erratum in

Abstract

Supported metal single atom catalysts (SACs) present an emerging class of low-temperature catalysts with high reactivity and selectivity, which, however, face challenges on both durability and practicality. Herein, we report a single-atom Pt catalyst that is strongly anchored on a robust nanowire forest of mesoporous rutile titania grown on the channeled walls of full-size cordierite honeycombs. This Pt SAC exhibits remarkable activity for oxidation of CO and hydrocarbons with 90% conversion at temperatures as low as ~160 oC under simulated diesel exhaust conditions while using 5 times less Pt-group metals than a commercial oxidation catalyst. Such an excellent low-temperature performance is sustained over hydrothermal aging and sulfation as a result of highly dispersed and isolated active single Pt ions bonded at the Ti vacancy sites with 5 or 6 oxygen ions on titania nanowire surfaces.

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Conflict of interest statement

A U.S. non-provisional patent (Application No.: 16/465,981) on catalyst methods of making, with P.-X.G. and S.H. as co-inventors, has been filed by the University of Connecticut.

Figures

Fig. 1
Fig. 1. Synthesis and structure of single Pt atoms supported on rutile TiO2 nanowire arrays.
a Schematic illustration of integration process of Pt1/TiO2 nanowire array forest onto ceramic monoliths and physicochemical and catalytic characteristics of such DOC catalytic converters. b Cross-sectional and c top view SEM images of rutile TiO2 NA on a cordierite honeycomb; inset: low-magnification cross-sectional view of cordierite substrate interface with conformably distributed TiO2 nanowire forest. d HAADF STEM of a rutile nanowire bundle. The arrays of dark spots on the HAADF STEM image identified the mesoporosity of the TiO2 nano-arrays. e–g ac-HAADF STEM images of Pt1/TiO2 NA prepared by microwave-assisted dip-coating (0.71 gPt L−1) (e) before, (f) after hydrothermal aging at 700 °C for 100 h, and (g) after hydrothermal aging at 700 oC for 100 h followed by simulated CDC exhaust test treatment. The bright dots on the surface of TiO2 are Pt atoms, as pointed by red arrow-heads.
Fig. 2
Fig. 2. Characterization of the Pt single-atom species on TiO2 NW and NA surfaces.
a k2-weighted Fourier-transformed EXAFS spectra of Pt1/TiO2 NW. Pt NP/TiO2 NA, Pt foil, and PtO2 are employed as references. b Normalized XANES spectra at the Pt L3 edge of Pt1/TiO2 NW under in situ CO oxidation. c Core Pt 4 f XPS spectrum of the Pt1/TiO2 NW. d The proposed Eley-Rideal mechanism for CO oxidation on Pt1/TiO2 NA. The reaction cycle shows the structure of intermediates and transient state (TS) of the key elementary steps. The inset shows the calculated energy profile. e In situ DRIFT spectra of CO adsorption and oxidation at 30 and 100 °C of Pt1/TiO2 NA, and f, H2-TPR profile of Pt1/TiO2 NW.
Fig. 3
Fig. 3. Diesel oxidation performance of Pt1/TiO2 NA integrated monoliths.
a Light-off curves for Pt1/TiO2 NA (0.71 gPt L−1) in the CDC simulated exhaust. b Comparison of the DOC activity in the CDC simulated exhaust between P1/TiO2 NA (0.71 gPt L−1) and Pt NP/TiO2 NA (1.73 gPt L−1). c Durability of the Pt1/TiO2 NA in the simulated exhaust. d, e Sulfur-poisoning effects on the DOC activity of Pt1/TiO2 NA (1.73 gPt L−1) in the LTC-D simulated exhaust. f Transient (upper panel) and cumulative (lower panel) THC emission in the transient gas conditions mimicking a HDD FTP as running on a HDD certified 2010 Cummins ISB (6.7 L) 320 hp engine for fresh (blue) and aged (red) Pt1/TiO2 NA (0.53 gPt L−1). A commercial DOC monolith with double PGM loading (1.06 g L−1) was employed as the reference.
See this image and copyright information in PMC

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