Hydrogen Peroxide Electrosynthesis in a Strong Acidic Environment Using Cationic Surfactants

The two-electron oxygen reduction reaction(2e^(−)-ORR)can be exploited for green production of hydrogen peroxide(H_(2)O_(2)),but it still suffers from low selectivity in an acidic electrolyte when using non-noble metal catalysts.Here,inspired by biology,we demonstrate a strategy that exploits the micellization of surfactant molecules to promote the H_(2)O_(2)selectivity of a low-cost carbon black catalyst in strong acid electrolytes.The surfactants near the electrode surface increase the oxygen solubility and transportation,and they provide a shielding effect that displaces protons from the electric double layer(EDL).Compared with the case of a pure acidic electrolyte,we find that,when a small number of surfactant molecules were added to the acid,the H_(2)O_(2)Faradaic efficiency(FE)was improved from 12%to 95%H_(2)O_(2)under 200 mA cm^(−2),suggesting an 8-fold improvement.Our in situ surface enhanced Raman spectroscopy(SERS)and optical microscopy(OM)studies suggest that,while the added surfactant reduces the electrode’s hydrophobicity,its micelle formation could promote the O_(2) gas transport and its hydrophobic tail could displace local protons under applied negative potentials during catalysis,which are responsible for the improved H_(2)O_(2)selectivity in strong acids.