Optimization of an airbrush-spray deposition method to fabricate copper-based gas diffusion electrodes.

Abstract

Carbon dioxide emissions are a global problem. Its excess is increasing, and therefore there are more and more lines of research to be able to reuse this excess of CO2. One way to take advantage of this excess is through the electrochemical reduction of carbon dioxide to obtain chemical products such as ethylene (C2H4), methanol (CH3OH), methane (CH4), carbon monoxide (CO), etc. Among these, ethylene production is the most extensively studied, due to its significance as one of the most widely used polymers in the industry. Continuous flow cell with gas diffusion electrodes (GDEs) are usually investigated to carry out the CO2RR at industrial levels due to its simple configuration. In these advanced electrochemical systems, GDEs are crucial compounds. With respect to its fabrication, advanced fabrication techniques, such as precision coating methods and controlled drying processes can be required. The use of a CNC airbrush is an advanced technique that offers high precision, uniformity and repeatability, thereby improving the quality and performance of the manufactured GDEs. The technique is particularly useful for applications that require high consistency and detailed control of the deposition of the catalyst layer. In this line, this project will try to optimize an airbrush-spray deposition method to fabricate copper-based gas diffusion electrodes for the reduction of carbon dioxide to ethylene. With this aim, parameters such as the displacement on the x and y axis of the airbrush, the height between the airbrush nozzle and the electrode, the displacement velocity and the aperture of the airbrush were investigated using Cu2O-CeO2 catalyst. Characterization and electrochemical results suggested that the presence of cracks decreases the hydrophobicity of GDE and causes a decrease in selectivity towards ethylene, respectively. On the other hand, the presence of a surface of the catalytic layer with roughness is important to favour the electroreduction of CO2 to ethylene. As proposal to fabricate copper-based GDEs, the best parameters for the deposition of its catalytic layer with an automated airbrush are: 1.5 mm displacement on the x and y axis, -100 mm height of the nozzle of the airbrush, 3500 mm/min as velocity of displacement and an aperture less than 7.5.