Manganese oxides are more stable but are not nearly active...

Manganese oxides are more stable but are not nearly active enough. By combining them, the researchers hoped to take advantage of their complementary properties. They also had to consider the high current density needed for practical application outside the laboratory.“For industrial-scale hydrogen production, we needed to set our study’s target current density to about 10 to 100 times higher than what has been used in past experiments,” co-author Shuang Kong said. “The high currents led to a number of problems such as physical decomposition of the catalyst.”Eventually, the team overcame these issues by trial and error and discovered an active and stable catalyst by inserting manganese into the spinel lattice of Co3O4, producing the mixed cobalt manganese oxide Co2MnO4.In their paper, the experts report that activation levels for Co2MnO4 were close to those for state-of-the-art iridium oxides. QUOTE
Interesting article that could be developed in the future IMO

https://www.mining.com/endangered-metals-not-needed-anymore-to-produce-hydrogen-from-water/