Coordination symmetry breaking in a cobalt Prussian blue analogue redirects the oxygen reduction pathway.

Coordination-symmetry breaking of cobalt sites in a macroporous cobalt hexacyanoferrate (macro-CoHCF), achieved via silica-templated confined crystallization, redirects oxygen reduction selectivity from the 4e- to the 2e- pathway. The resulting low-symmetry Co centers weaken *OOH adsorption and suppress O-O cleavage, boosting H2O2 selectivity from 15% to ∼90%.