Electrochemical reduction of CO₂ at temperatures below 300°C

Reduction of CO₂ at intermediate temperatures (T<300°C) is a tempting way to produce hydrocarbons. One benefit of performing CO₂ reduction below 300°C is that it would possibly allow a single process for production of hydrocarbons. CsH₂PO₄, BaHPO₄ and a composite thereof have been investigated as electrolyte materials both with respect to thermal stability and to conductivity. BaHPO₄ showed an improved thermal stability compared to CsH₂PO₄, but it did at the same time exhibit a low conductivity (1·10^-6 S cm^-1 at 304°C). CsH₂PO₄ started to dehydrate at 249°C, but this dehydration was shown to be reversible. Its conductivity was measured to be 2·10^-2 S cm^-1 at 240°C. Full cells with copper as the CO₂ reduction catalyst have been manufactured and tested in CO₂ containing atmospheres. Initial performance of 34 mA cm^-2 at 245°C has been achieved. ©The Electrochemical Society.