Renewable electricity can be applied to the reduction of water to generate hydrogen as a carbon neutral fuel. The discovery of new heterogeneous electrocatalysts for this reaction has been driven by the use of activity descriptors, or thermodynamic parameters that predict and rationalize catalytic activity. For homogeneous hydrogen evolution electrocatalysts that proceed through protonation of a metal hydride intermediate, we discuss how hydricity can be used as an activity descriptor. The discrete energies associated with molecular systems results in different utility compared to heterogeneous catalysis. Specifically, in molecular systems hydricity can be used to determine the functional or optimal pH range of hydrogen evolution, as well as the conditions for the selective electrochemical generation of metal hydride intermediates for reduction of alternative substrates without concomitant hydrogen formation.

Hydricity as an activity descriptor for molecular hydrogen evolution electrocatalysts

253rd National Meeting (2017)

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