Direct synthesis of methane from CO2/H2O in an oxygen-ion conducting solid oxide electrolyser

Abstract

Synthetic fuels produced from CO₂/H₂O are an attractive alternative energy carrier. Here we demonstrate a novel strategy to electrochemically convert CO₂/H₂O into hydrocarbon in a single step in an oxygen-ion conducting solid oxide electrolyser. Methane was directly synthesized in an efficient electrolyser with configuration of (anode) (La_0.8Sr_0.2)_0.95MnO_3−δ/YSZ/La_0.2Sr_0.8TiO_3+δ (cathode) by combining coelectrolysis of CO₂/H₂O and in situ Fischer–Tropsch-type synthesis. We demonstrate a high Faradaic yield of CO/H₂ and lower methane yield, which shows that the limit on conversion efficiency comes from the heterogeneous catalysis process. Electrochemical results also show that the electrochemical reduction of La_0.2Sr_0.8TiO_3+δ cathode is the main process at low electrical voltages while the coelectrolysis is the main process at high voltages.