Carbonate-carbonate coupling on platinum surface promotes electrochemical water oxidation to hydrogen peroxide.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39397014.
- Also identified by DOI 10.1038/s41467-024-53134-3 and PMC identifier 11471758.
- Licence recorded as CC BY-NC-ND.
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Abstract
Water electro-oxidation to form H<sub>2</sub>O<sub>2</sub> is an important way to produce H<sub>2</sub>O<sub>2</sub> which is widely applied in industry. However, its mechanism is under debate and HO<sub>(ads)</sub>, hydroxyl group adsorbed onto the surface of the electrode, is regarded as an important intermediate. Herein, we study the mechanism of water oxidation to H<sub>2</sub>O<sub>2</sub> at Pt electrode using in-situ Raman spectroscopy and differential electrochemical mass spectroscopy and find peroxide bond mainly originated from the coupling of two CO<sub>3</sub><sup>2-</sup> via a C<sub>2</sub>O<sub>6</sub><sup>2-</sup> intermediate. By quantifying the <sup>18</sup>O isotope in the product, we find that 93% of H<sub>2</sub>O<sub>2</sub> was formed via the CO<sub>3</sub><sup>2-</sup> coupling route and 7% of H<sub>2</sub>O<sub>2</sub> is from OH<sub>(ads)</sub>-CO<sub>3</sub><sup>•-</sup> route. The OH<sub>(ads)</sub>-OH<sub>(ads)</sub> coupling route has a negligible contribution. The comparison of various electrodes shows that the strong adsorption of CO<sub>3(ads)</sub> at the electrode surface is essential. Combining with a commercial cathode catalyst to produce H<sub>2</sub>O<sub>2</sub> during oxygen reduction, we assemble a flow cell in which the cathode and anode simultaneously produce H<sub>2</sub>O<sub>2</sub>. It shows a Faradaic efficiency of 150% of H<sub>2</sub>O<sub>2</sub> at 1 A cm<sup>-2</sup> with a cell voltage of 2.3 V.