On the activity and stability of Sb2O3/Sb nanoparticles for the electroreduction of CO2 toward formate

The development of new electrocatalysts with improved properties for the electrochemical reduction of CO2 is being the objective of innumerable contributions. In this contribution, the electrochemical reduction of CO2 to formate on novel carbon-supported antimony nanoparticles (Sb/C NPs) is studied. The carbon-supported Sb2O3/Sb nanoparticles were synthesised using a simple methodology at room temperature and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The Sb2O3/Sb/C electrodes were prepared by air-brushed onto a carbon paper and were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The Sb2O3/Sb/C electrodes were also electrochemically characterized by cyclic voltammetry and displayed a clear activity for CO2 electroreduction. To evaluate the properties of the electrodes for the reduction of CO2, electrolyses at different potentials were systematically conducted. Hydrogen and formate were the only products found. The faradic efficiency towards formate was found to be about 20%. This FE was in good agreement with previous finding obtained with comparable system. Interestingly, 24-hour tests were carried out to analyse the stability of the material under working conditions. The results indicate that Sb2O3/Sb-based electrodes display a remarkably better stability than other nanostructured electrocatalysts such as Sn or Bi.