Direct electrosynthesis of pure aqueous H<sub>2</sub>O<sub>2</sub> solutions up to 20% by weight using a solid electrolyte.
basic_science · Level V
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- Record sourced from PubMed, PMID 31601767.
- Also identified by DOI 10.1126/science.aay1844.
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Abstract
Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) synthesis generally requires substantial postreaction purification. Here, we report a direct electrosynthesis strategy that delivers separate hydrogen (H<sub>2</sub>) and oxygen (O<sub>2</sub>) streams to an anode and cathode separated by a porous solid electrolyte, wherein the electrochemically generated H<sup>+</sup> and HO<sub>2</sub> <sup>-</sup> recombine to form pure aqueous H<sub>2</sub>O<sub>2</sub> solutions. By optimizing a functionalized carbon black catalyst for two-electron oxygen reduction, we achieved >90% selectivity for pure H<sub>2</sub>O<sub>2</sub> at current densities up to 200 milliamperes per square centimeter, which represents an H<sub>2</sub>O<sub>2</sub> productivity of 3.4 millimoles per square centimeter per hour (3660 moles per kilogram of catalyst per hour). A wide range of concentrations of pure H<sub>2</sub>O<sub>2</sub> solutions up to 20 weight % could be obtained by tuning the water flow rate through the solid electrolyte, and the catalyst retained activity and selectivity for 100 hours.