Electrochemical reduction of CO2 (ECR) powered by renewable energy sources have emerged as a powerful technology to fight a global battle against climate change. Considering the huge industrial importance (global market size of $230 billion) of ethylene and its contribution towards CO2 emission (~150 Mt of CO2 emission per year), it is necessary to find sustainable methods for synthesizing ethylene. Therefore, this work focus on finding new avenues for electrochemical reduction of CO2 to ethylene with higher product selectivity, high current density and long-term stability. A methodology is developed for catalyst regeneration under controlled microenvironments by applying oscillating reduction and oxidation currents. A zero-gap two electrode electrochemical cell is used which consists of Cu mesh, aqueous electrolyte (0.1 M KHCO3 and 1M KCl) through which CO2 is sparged continuously, Ni foam as anode and a membrane between cathode and anode. The factors under consideration are: (1) reduction current , (ii) oxidation current, (iii) reduction time ; (iv) oxidation time and (v) electrolyte flow rate and (vii) catalyst surface area. In addition to this, the efficient removal of gaseous products is ensured by optimizing the inlet/outlet design of electrochemical cell. The experimental results reveal that reduction current and oxidation time are the important parameters affecting the performance of electrochemical cell. The faradaic efficiency (FE) and ethylene selectivity increases with increase in oxidation time and attains maxima at =5s. As compared to constant current operations, the oscillations lead to enhanced FE by 15%. The characterization techniques such as XPS and SEM helps in identifying the presence of mixed Cu oxides and dynamic surface restructuring which attributes to higher selectivity toward ethylene. The long-term stability tests show 20% reduction in FE after 7 days of operation.
