Electrochemical Reduction of Carbon Dioxide on Au Nanoparticles: An in Situ FTIR Study
journal contributionposted on 19.09.2019, 14:34 by Shuai Chen, Aicheng Chen
For the conversion and storage of renewable energy, the electrochemical reduction of CO2 to hydrocarbon fuels and chemicals comprises one of the most promising strategies. A number of studies have focused on the development of robust electrocatalysts for the reduction of CO2 with high efficiency and selectivity. Most of the proposed mechanisms of the CO2 reduction are based primarily on theoretical calculations. Although a few studies have been dedicated to the in situ direct detection of intermediates, the mechanisms are still unclear and questionable. As Au is one of the most efficient catalysts for CO2 reduction, it is selected as an electrocatalyst model for this work to examine intermediates and to explore the kinetics of the electrochemical reduction of CO2. In this study, gold nanoparticles were prepared by a facile sputtering method. In situ attenuated total reflection Fourier transform infrared spectroscopy (FTIR) was employed to investigate the reaction mechanism of the electrochemical reduction of CO2 at the Au nanoparticles. To assign the IR peaks and to identify the formed intermediates and products, H2O and D2O were used as solvents. Our experimental results have provided the direct evidence of the formation of *COO– species on the Au nanoparticles, confirming that *COO– is one of the main intermediates during the CO2 activation. Besides the main product CO, another product HCOO– was detected during the CO2 reduction on gold nanoparticles. The amount of the formed CO and formate products depends on the applied cathodic potential. The mechanism of CO and formate formation on the Au nanoparticle surface is proposed; the kinetics of the CO2 reduction has been further studied using the in situ FTIR technique. The findings from this study provide direct IR spectroscopic evidence of the CO2 reduction mechanism at the Au nanoparticles; the approaches reported in the present study would be useful to investigate various electrocatalytic reactions for energy and environmental applications.