Palladium is an important catalyst in many catalytic reactions with diversity of technological applications. Apart from the pure metal, catalytic activity is being increasingly attributed also to palladium oxides, which however remain poorly characterized. The only thoroughly scientifically studied and technologically exploited palladium oxide is PdO. In our present study we focus on theoretical examination of PdO₂. Its formation was observed under elevated hydrostatic pressure and rutile structure was proposed [1,2]. Using Density Functional Theory modelling, we have obtained more detailed information about existence of PdO₂ including possible polymorphs with distinct oxygen anions (O^2-, (O₂)^2-), details of crystal structures, vibrational properties and thermodynamic stability [3]. Here we will show that apart from the rutile structure, PdO₂ can form in variety of polymorphs with much more favorable formation enthalpies. We examine these polymorphs in relation to PtO₂ and calculate their IR/Raman fingerprints in broader pressure range that can help to identify them in future experiments.

Acknowledgement: The European Regional Development Fund, Research and Innovation Operational Programme, for project No. ITMS2014+: 313011W085; Scientific Grant Agency of the Slovak Republic, grant No. VG 1/0223/19; the Slovak Research and Development Agency, grant No. APVV-18-0168; Aurel supercomputing infrastructure in CC of Slovak Academy of Sciences acquired in projects ITMS 26230120002 and 26210120002 funded by ERDF.

References:

[1] I. S. Shaplygin, G. L. Aparnikov, V. B.Lazarev, Zhurnal Neorganicheskoi Khimii, 23, 884 (1978).

[2] G. I. Goncharenko, V. B. Lazarev, I. S. Shaplygin, Zhurnal Neorganicheskoi Khimii, 30, 3032 (1985).

[3] D. Fabušová, Bachelor thesis 2020, available at https://opac.crzp.sk/