Genesis of RuxSey Nanoparticles by Pyrolysis of Ru4Se2(CO)11: A Combined X-ray in Situ and DFT Study

The cluster-like RuxSey (x ≈ 2, y ≈ 1) compound can be prepared by simple pyrolysis of the carbonyl complex Ru4Se2(CO)11 in inert gas. We have observed this process in situ using X-ray diffraction. The clusters exhibit a disordered hcp-type structure with an average size of 1.7 nm. Selenium is probably coordinated at the surface of ruthenium nanoparticles. Up to 430 °C, these nanoparticles are stable in an inert ambient, except for a certain growth in size. Above this temperature, the system splits into two phases: hcp-type ruthenium particles, which are probably free of Se, and a ruthenium-diselenide phase: RuSe2. Using density functional theory (DFT), we studied the surface structure of RuSe2 and found a preference for Se-rich surfaces. Transferring to the nanoparticles, this might correspond to the picture of a Ru core and either a RuxSey- or a pure Se shell (adsorbate layer).