Coke-free direct formic acid solid oxide fuel cells operating at intermediate temperatures

▸ Formic acid is used as a fuel for solid oxide fuel cells for the first time. ▸ Coke formation on Ni-YSZ anode in formic acid vapor is negligible above 600 °C. ▸ Peak power density of 571 mW cm−2 is obtained with formic acid at 800 °C.