The Sabatier principle in heterogeneous catalysis and electrocatalysis states that reactants and intermediates should bind neither too strongly nor too weakly to a surface for active catalysts. The binding of hydrogen atoms to the surface is often an important component of catalysis, and the surface-H bond dissociate free energy (BDFE) is a common energetic descriptor for processes such as the hydrogen evolution reaction (HER). Yet for the rapidly emerging pnictide and chalcogenide classes of catalysts, little is known about the binding of H at their solid/solution interfaces. This talk will describe the reactions of nanoscale pnictide and chalcogenide materials, especially CoP and MoS<sub>2</sub>, with molecular hydrogen atom donors. As one example, 1,8-dichlorohydroanthraquinone can transfer H-atoms to the materials. Titration of the hydrogenated materials with 2,4,6-tri-<i>tert</i>-butylphenoxy radical forms the corresponding phenol. Alternatively, H-atoms on the materials can be removed by hydrogenating alkynes. Such experiments measure how many reactive hydrogen atoms were present on (or in) the materials. By varying the X–H BDFEs in the molecular H-atom transfer reagents, a measure of the surface–H BDFEs can be obtained. Only reagents with low bond dissociation free energies (BDFEs) X-H are capable of introducing H-atoms to any of the studied materials, in line with the Sabatier principle. These results, and extensions to metal and metal-oxide nanocrystals, will provide new molecular-level understanding of heterogeneous processes.

Hydrogen-atom transfer chemistry of pnictide, chalcogenide and other materials

2019 Spring National Meeting

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