Search Results (2)

Unlike the flat Cu sheet, we employed Cu foam to explore the specific porous effect on the expanding specific area. We found that the foam structure is superior to the sheet feature in the specific location from the morphology investigation. In the practical measurement of surface area, we found that the adsorbate could aptly agglomerate, resulting in a consequential block in the transport path. The specific location of the Cu foam was underestimated because the channels of the deep foam layer were blocked by the agglomerated adsorbate. To explore the protonation process of the electro-reduction, we adopted the carbonate electrolyte as the control group in contrast to the experimental group, the bicarbonate electrolyte. In the carbonate electrolyte, the primary intermediate was shown to be CO molecules, as verified using XPS spectra. In the bicarbonate electrolyte, the intermediate CO disappeared; instead, it was hydrogenated as a hydrocarbon intermediate, CHO*. The bicarbonate ion was also found to suppress electrocatalysis in the deep structure of the Cu foam because its high-molecular-weight intermediates accumulated in the diffusion paths. Furthermore, we found a promotion of the oxidation valence on the electrode from Cu₂O to CuO, when the electrode structure transformed from sheet to foam. Cyclic voltammograms demonstrate a succession of electro-reduction consequences: at low reduction potential, hydrogen liberated by the decomposition of water; at elevated reduction potential, formic acid and CO produced; and at high reduction potential, CH₄ and C₂H₄ were formed from −1.4 V to −1.8 V. Full article

Nowadays, the self-accelerating increase in global temperatures strengthens the idea that the cutting of CO₂ emissions will not be enough to avoid climate change, thus CO₂ from the atmosphere must be removed. This gas can be easily trapped by converting it to bicarbonate using hydroxide solutions. However, bicarbonate must be converted into a more valuable product to make this technology profitable. Several studies show great efficiency when reducing bicarbonate solutions saturated with pure CO₂ gas to formate. However, those approaches don’t have a real application and our objective was to obtain similar results without pure CO₂ saturation. The method consists of electroreduction of the bicarbonate solution using bulk tin (Sn) as catalysts. Tin is a relatively cheap material that, according to previous studies performed in saturated bicarbonate solutions, shows a great selectivity towards formate. The ¹H NMR analysis of bicarbonate solutions after electroreduction show that, without pure CO₂ gas, the faradic efficiency is around 18% but almost 50% for saturated ones. The formate obtained could be used to power formate/formic acid fuel cells obtaining a battery-like system, with greater energy density than common lithium batteries, but electroreduction efficiency needs to be improved to make them competitive. Full article