No abstract

The industrialization of the electrochemical reduction of CO 2 toward CO in aqueous electrolytes has recently been started using silver-based gas diffusion electrodes. The performance of a CO 2 -to-CO electrolyzer model on a 10-cm 2 cell size is assessed with respect to operating pressure, achievable current density at faradaic efficiency of CO above 90 %, composition of gas streams and operational lifetime. Operational lifetime has exceeded 1500 h. The first scaling step to 300 cm 2 has been accomplished. The rated power of such a cell is around 300 W.

We report on the long-term stability of the electrochemical reduction of CO 2 at copper sheet electrodes by continuously applying rectangular, pulsed voltage cycles in series. Each pulse cycle consisted of an anodic and a cathodic voltage level. The parameters of the pulse cycle were systematically modified: cathodic (−1.5...−1.8 V) and anodic voltage levels (−0.88...+0.15 V), and ratio of anodic to cathodic pulse duration (5 s:5 s...5 s:500 s). The electrolysis runs were conducted in a divided H-cell. Volatile reaction products (CO, CH 4 , C 2 H 4 , H 2 ) were analyzed with a gas chromatograph in intervals of 7.3 min. We achieved fairly stable faradaic efficiencies (FE) for hydrocarbon formation in the range of 20 to 35% FE for C 2 H 4 and 20 to 50% FE for CH 4 during 16 h of electrolysis and a remarkable suppression of hydrogen evolution reaction (HER) down to 10% FE. Additionally, we show data of two long-term electrolysis runs of 85 h and 95 h duration, respectively. Even for this prolonged electrolysis times, an outstanding, fairly constant suppression of HER and a high efficiency for the formation of carbon containing gaseous products (CO, CH 4 , C 2 H 4 ) was achieved.

No abstract

No abstract