Influence of sonication on co-precipitation synthesis of copper oxide catalyst for CO2 electroreduction

The need to reduce greenhouse gas emissions and increase our energy supply makes the electrochemical reduction of CO2 (CO2R) a very attractive alternative to produce non-fossil-based fuels or chemicals. Copper-based catalysts is one of the catalyst that most efficiently promote the formation of species with one or more carbon-carbon bonds from the electrochemical reduction of CO2 [1]. Because the catalyst preparation method has an influence on the physicochemical properties and on the electrocatalytic performance[2], in this work, it was decided to evaluate the effect of the ultrasound application (US) on the shape and size of the particles obtained, its electrocatalytic activity and its selectivity to products of interest. For this purpose, sonication was carried out at different percentage amplitudes of ultrasonic power (23, 30 and 37%) during the aging time of the synthesis. Physical characterization was carried out by using different techniques including X-ray diffraction, BET and filed-emission scanning electron microscopy (FESEM). Electrochemical tests for CO2 reduction were done under ambient conditions. Regarding the physical characteristics, we found that pore size distribution is narrower by increasing the US amplitude. On the other hand, there is no significant difference in morphology and dimension of particles. However, the surface area increased with the use of ultrasound, this is attributed to a better dispersion created by acoustic cavitation. Ultrasound has also an effect on Copper-based catalysts performance; in this case, the selectivity towards H2 and C1 products (CO and formate) was enhanced. In addition, an increase in productivity of CO2R products was obtained with respect to the synthesized catalysts that were not assisted by ultrasound (> 3-fold). These results motivate us to further explore in what other ways acoustic cavitation phenomenon can influence the physical characteristics of the catalysts and, in turns, their performance for the electrochemical reduction of CO2.