Electrolysis of Carbon Dioxide in a Solid Oxide Electrolyzer with Silver-Gadolinium-Doped Ceria Cathode

Splitting CO 2 into CO and pure O 2 at high temperature through solid oxide electrolyzers (SOEs) could provide an efficient way for energy storage and CO 2 utilization. Tubular solid oxide electrolysis cells, with yttrium-stabilized-zirconia (YSZ) as electrolyte, strontium-doped lanthanate (LSM) as anode, cermet of Ag-GDC (gadolinium-doped-ceria) as cathode, is fabricated and operated as SOEs for electrolysis of pure CO 2 . Such an SOE shows a minimum electrolyzing voltage of 0.70 V and a current density of 1359 mA cm −2 at 2 V. Its CO production rates are 3.1, 6.6 and 10.0 mL min −1 at electrical currents of 0.5, 1.0 and 1.5 A, respectively, at 800°C. The corresponding Faraday efficiencies are 88.6%, 94.3%, and 95.2%, and the electrical energy conversion efficiencies are 75.4%, 65.2%, and 56.5%, respectively. An SOE with Ag-GDC electrode is steadily operated at 1.59 V for pure CO 2 electrolysis at 800°C for 18 h, suggesting that Ag-GDC is a promising cathode material for SOEs of CO 2 electrolysis.