In recent years, the concept of rechargeable aqueous Zn–CO₂ batteries has attracted extensive attention owing to their dual functionality of power supply and simultaneous conversion of CO₂ into value-added chemicals or fuels. The state-of-the-art research has been mainly focused on the exploration of working mechanisms and catalytic cathodes but hardly applies an integrative view. Although numerous studies have proven the feasibility of rechargeable aqueous Zn–CO₂ batteries, challenges remain including the low CO₂ conversion efficiency, poor battery capacity, and low energy efficiency. This review systematically summarizes the working principles and devices, and the catalytic cathodes used for Zn–CO₂ batteries. The challenges and prospects in this field are also elaborated, providing insightful guidance for the future development of rechargeable aqueous Zn–CO₂ batteries with high performance.

Prussian blue analogs (PBAs) are effective precatalysts for the oxygen evolution reaction (OER); however, the underlying mechanism of their electrochemical activation is still not well elucidated. In this study, we designed and constructed PBA-based precatalysts to determine the electrochemical activation mechanism and achieve high-efficiency OER. The PBAs undergo in situ electrochemical transformation to form the corresponding metal (oxy)hydroxides (M(O)OH) as the true OER catalyst. More importantly, the hexacyanoferrate ligands undergo repetitive interfacial coordination/etching with/from M(O)OH during the activation process. The distinct mechanism could achieve in situ Fe doping and enable defect incorporation. The defect-enriched Fe-NiOOH derived from a well-designed NiHCF/Ni(OH)₂ precatalyst requires a low overpotential of 227 mV to reach a current density of 10 mA cm⁻² and works stably at 130 mA cm⁻² over 100 h. This study provides fundamental insights into the electrochemical activation mechanism for developing advanced precatalysts for OER.