Activity–Stability Trends for the Oxygen Evolution Reaction on Monometallic Oxides in Acidic Environments

Abstract

In the present study, we used a surface-science approach to establish a functional link between activity and stability of monometallic oxides during the OER in acidic media. We found that the most active oxides (Au ≪ Pt < Ir < Ru ≪ Os) are, in fact, the least stable (Au ≫ Pt > Ir > Ru ≫ Os) materials. We suggest that the relationships between stability and activity are controlled by both the nobility of oxides as well as by the density of surface defects. This functionality is governed by the nature of metal cations and the potential transformation of a stable metal cation with a valence state of n = +4 to unstable metal cation with n > +4. A practical consequence of such a close relationship between activity and stability is that the best materials for the OER should balance stability and activity in such a way that the dissolution rate is neither too fast nor too slow.

Towards Versatile and Sustainable Hydrogen Production through Electrocatalytic Water Splitting: Electrolyte Engineering

“…A trade‐off between the activity and stability is reported for the OER in acidic environments, even for the most active oxides, IrO 2 and RuO 2 149. As expected from the Pourbaix diagram shown in Figure 11,151 the cationic state of the metals is thermodynamically more favored at lower pH levels, which is consistent with the nature of their dissolution into solution.…”

“…Improving not only the activity but also the stability is a challenge for OER electrodes, particularly in acidic149 and near‐neutral pH150 environments. A trade‐off between the activity and stability is reported for the OER in acidic environments, even for the most active oxides, IrO 2 and RuO 2 149.…”

MAXNET Energy – Focusing Research in Chemical Energy Conversion on the Electrocatlytic Oxygen Evolution

“…At high pH ferrous metals are materials of choice, as they are thermodynamically stable [43]. For studied materials, more stable electrodes were typically less active, confirming at least in this case the earlier mentioned inverse activity-stability correlation [36]. Due to the fact that Ru is not stable, most of the research on the acidic OER has been devoted to optimization of Ir-based catalysts.…”

“…A thermodynamic explanation for the observed oxide dissolution during OER was recently provided by Binninger et al [35]. The important outcome of these studies is that in the region of OER potentials, the stability of the material is not only defined by its "nobility," and that there are deviations from the inverse relationship of activity and stability often suggested in literature [36]. As an example, Au as the noblest of the metals [37] is neither stable during OER in acidic media nor active (at least in the classical view of the activity using exchange current density or onset potential of OER) [38][39][40].…”

Exploitation of the Large‐Area Basal Plane of MoS2 and Preparation of Bifunctional Catalysts through On‐Surface Self‐Assembly

“…Unlike Ni(abt) 2 for OER, each step is moderate for the Co site of on‐MoS 2 Co(abt) 2 (see Figure 5c). The potential‐determining step is the process from OH* to O* and the overpotential η is only 0.43 V, comparable to traditional precious metal‐based OER catalysts in a range of about 0.3–0.7 V,51, 58, 59 showing that OER can be efficiently catalyzed at the Co site of on‐MoS 2 Co(abt) 2 . Our calculations show that OER can be catalyzed by Co(abt) 2 along the four‐electron pathway.…”