where A is Li, Na, K, Cs) on OER activity of NiOOH. The consistent activity trend of Cs + > Na + > K + > Li + was found for both pure NiOOH as well as NiOOH containing iron impurities. Combining the deprotonation and alkali metal cation adsorption effects, one may speculate that the interaction of cations with negatively charged surface oxygen species (NiOO-A + ) plays an important role in stabilizing cations on the surface .