In situ surface spectroscopy and microscopy of zirconia based model catalysts

Günther Rupprechter *

Institute of Materials Chemistry, Technische Universität Wien, 1060 Vienna, Austria

*Corresponding address (Email: guenther.rupprechter@tuwien.ac.at, +43-158801165100)

Abstract

Zirconia supported Ni and Pt nanoparticles are important catalysts for methane steam and dry reforming. To examine such reforming catalysts by a surface science approach, different models were used: (i) an ultrathin ZrO2 trilayer (O-Zr-O) film grown on Pt3Zr(0001), (ii) ZrO2 islands on Pt(111) as inverse model catalysts, and (iii) ZrO2 supported Pt, Pd and Rh particles. Preferentially, the active functioning model systems were studied under in situ conditions, at (near) atmospheric pressure and at elevated temperature.

This requires application of in situ surface spectroscopy, such as sum frequency generation (SFG) laser spectroscopy, polarization-modulation infrared reflection absorption spectroscopy (PM-IRAS) and near atmospheric pressure X-ray photoelectron spectroscopy (NAP-XPS). To image (“see”) ongoing surface reactions by in situ surface microscopy, photoemission electron microscopy (PEEM) was applied. Typically, the in situ studies were performed in lock-step with theory.

This approach should yield a more complete view of the catalytically relevant atomic and electronic surface structure of catalysts, of adsorbed species, and of molecular details that steer reaction activity and selectivity. The following processes will be disussed:

i) CO2 activation by H2O on ultrathin ZrO2 trilayer (O-Zr-O) film on Pt3Zr(0001) (NAP-XPS, PM-IRAS) Surf. Sci. 679 (2019) 139–146,

ii) methane dry reforming on ZrO2/Pt(111) inverse model catalysts (NAP-XPS, IRAS) J. Phys.: Cond. Matt. 30 (2018) 264007 (1-12),

iii) CO oxidation and H2 oxidation on ZrO2 supported Pt, Pd and Rh particles (SFG, NAP-XPS, PEEM) Nat. Mat. 17 (2018) 519-522; Nat. Comms 9 (2018) 600; Catal. Lett. 148 (2018) 2947-2956, Surf. Sci. 679 (2019) 163–168.

These examples will illustrate how in situ surface spectroscopy/microscopy enabled to observe novel phenomena (such as OH assisted CO2 activation, details of SMSI, suppression of coke formation, lang-range metal/oxide interface effects).

Keywords: model catalysis; applied catalysis; operando; surface science; zirconia