Structural evolution of atomically dispersed Pt catalysts dictates reactivity

Abstract

The use of oxide-supported isolated Pt-group metal atoms as catalytic active sites is of interest due to their unique reactivity and efficient metal utilization. However, relationships between the structure of these active sites, their dynamic response to environments and catalytic functionality have proved difficult to experimentally establish. Here, sinter-resistant catalysts where Pt was deposited uniformly as isolated atoms in well-defined locations on anatase TiO2 nanoparticle supports were used to develop such relationships. Through a combination of in situ atomic-resolution microscopy- and spectroscopy-based characterization supported by first-principles calculations it was demonstrated that isolated Pt species can adopt a range of local coordination environments and oxidation states, which evolve in response to varied environmental conditions. The variation in local coordination showed a strong influence on the chemical reactivity and could be exploited to control the catalytic performance.

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Fig. 1: Controlling chemical and catalytic reactivity of Ptiso via pretreatment.
Fig. 2: In situ AC-STEM characterization of Ptiso/TiO2.
Fig. 3: XAS of Ptiso/TiO2 catalysts.
Fig. 4: Structural models of Ptiso/TiO2.

Data availability

All the data reported in this paper are available from the corresponding author upon request.

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Acknowledgements

We acknowledge S. Hanukovich for his assistance with the microkinetic modelling in Supplementary Fig. 8 and the TPR experiment in Supplementary Fig. 18. P.C. acknowledges funding from National Science Foundation (NSF) CAREER grant number CBET-1823189. The UCSB MRL Shared Experimental Facilities are acknowledged for use of the inductively coupled plasma–optical emission spectrometry equipment and are supported by the MRSEC Program of the NSF under award no. DMR 1720256; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). The work of H.V.T. and G.P. was supported by the Italian MIUR through the PRIN Project 2015K7FZLH SMARTNESS. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under contract no. DE-AC02-76SF00515. Co-ACCESS is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. TEM experiments was conducted using the facilities in the Irvine Materials Research Institute at the University of California-Irvine. The work at UC Irvine was supported by the National Science Foundation through the grant number DMR-1506535.

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Contributions

L.D. developed the catalyst synthesis; L.D. and J.R. performed infrared characterization and catalytic measurements; S.D. performed and analysed TEM measurements with supervision by X.P. and G.W.G.; L.D., A.S.H., A.B. and I.R. performed the XAS supervised by S.R.B.; A.B. performed the XAFS analysis; H.V.T. performed the DFT calculations supervised by G.P.; I.R. performed the inductively coupled plasma–optical emission spectrometry measurements. All authors analysed and interpreted the results and contributed to the preparation of the manuscript. P.C. conceived the project and oversaw all portions.

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Correspondence to Phillip Christopher.

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Supplementary Information

Extended materials and methods, text, Figs. 1–18, Tables 1–5, refs. 1–34

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DeRita, L., Resasco, J., Dai, S. et al. Structural evolution of atomically dispersed Pt catalysts dictates reactivity. Nat. Mater. 18, 746–751 (2019). https://doi.org/10.1038/s41563-019-0349-9

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