A review in Advanced Science covers tri-functional electrocatalysts designed to work in both rechargeable zinc-air batteries and water electrolysis for hydrogen production. The challenge is that one catalyst must handle three different reactions: oxygen reduction during battery discharge, oxygen evolution during charging, and hydrogen evolution during water splitting. Those reactions favor different active sites, so balancing them in one material is the hard part. The review also warns that good half-cell lab results often do not translate into good device performance. Real systems face carbon support corrosion, catalyst restructuring, and interface degradation under cycling. For anyone tracking clean energy storage or hydrogen economics, the takeaway is that catalyst overpotential alone is not enough. The metric that matters is overall system efficiency under real loads.
