Stability and activity of non-noble based catalysts toward the hydrogen evolution reaction -feasible electrocatalysts in acidic medium?
Résumé
Fundamental understanding of the behavior of non-noble based materials toward the hydrogen evolution reaction is crucial for
the successful implementation into practical devices. Through the implementation of a highly sensitive on-line inductively coupled
plasma mass spectrometer coupled to a scanning flow cell, an activity and stability protocol for non-noble electrocatalysts is presented. The studied catalysts comprise a range of compositions, including metal carbides (WC), sulfides (MoS2), phosphides (Ni5P4, Co2P), their base metals (W, Ni, Mo, Co) and their activity, stability and degradation behavior was elaborated and compared to platinum. It is shown that
the non-noble materials are stable at HER potentials but dissolve substantially when no current is flowing. Through pre- and post-
characterization of the catalysts, explanations of their stability (thermodynamics and kinetics) are discussed, challenges for the
application in real devices are analyzed, and strategies for circumventing dissolution are suggested. The precise correlation of
metal dissolution with applied potential/current density allows for narrowing down suitable material choices as replacement for precious
group metals as e.g. platinum and opens up new ways in finding cost-efficient, active and stable new-generation electrocatalysts