Precious metal free tunable manganese oxides for sustainable anion exchange membrane fuel cells.

Li2Mn0.9Sn0.1O3 cathodes in anion exchange membrane fuel cells achieve peak power densities above 1.0 W cm-2geo and 3.96 W mg-1Pt under H2/O2.

• Why it matters: Platinum-group metal removal from low-temperature polymer electrolyte fuel cell cathodes is needed, but activity and stability often trade off.
• What they did: The team doped atomically dispersed p-block Sn into Li2MnO3 and used operando X-ray absorption spectroscopy plus rapid freeze-quench 119Sn Mössbauer to track changes during oxygen reduction.
• The result: During oxygen reduction, Mn4+ is converted to Mn3+ while Sn4+ remains unchanged, supporting electronic-structure modulation that enables the reported power output.

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