Hydrogen peroxide (H₂O₂) as a low cost, safe and clean disinfection agent plays an important role in providing clean water for human society. Compared with complicated industrial anthraquinone process or direct catalytic synthesis from H₂ and O₂, the distributed production of H₂O₂ in a polymer electrolyte fuel cell system (PEFC) has numerous merits, including lower financial and energy cost, safer process, use of small-scale, easily deployable device.^1,2 For these reasons, there is strong interest in developing electrocatalysts with high activity and selectivity for H₂O₂ production via the electrochemical reduction of molecular oxygen. Up until now, H₂O₂ electrocatalysts have been based on precious-metal amalgams, which are costly, scarce, and difficult to handle safely due to the use of Hg.^2,3 Carbon-based electrocatalysts have been considered for H₂O₂ production,^4-6 as have been metal-free and nitrogen-containing molecular catalysts known to be selective for two-electron reduction of O₂ in various media.^7-9

In this presentation, we will demonstrate a new catalyst based on a small organic molecule that enables electrochemical production of H₂O₂ in an aqueous acidic electrolyte (0.5 M H₂SO₄). When adsorbed onto glassy carbon this molecular catalyst shows a high onset potential of around 0.6 V vs. RHE, and a specific current density > 1.3 mA/cm²_ECA at 0 V vs. RHE in electrochemical cell test. Rotating ring-disk electrode (RRDE) studies indicate high selectivity for H₂O₂ production, with H₂O₂ yield over 80%, and current efficiency over 67%. The durability of this molecule has been evaluated in an electrochemical cell, as well as in a PEFC. Based on experimental data and density functional theory (DFT) calculations, a two electron oxygen reduction mechanism on this molecular catalyst will be proposed.

References

(1) Centi, G.; Perathoner, S.; Abate, S. In Modern Heterogeneous Oxidation Catalysis; Wiley-VCH Verlag GmbH & Co. KGaA: 2009, p 253.

(2) Siahrostami, S.; Verdaguer-Casadevall, A.; Karamad, M.; Deiana, D.; Malacrida, P.; Wickman, B.; Escudero-Escribano, M.; Paoli, E. A.; Frydendal, R.; Hansen, T. W.; Chorkendorff, I.; Stephens, I. E. L.; Rossmeisl, J. Nat. Mater. 2013, 12, 1137.

(3) Verdaguer-Casadevall, A.; Deiana, D.; Karamad, M.; Siahrostami, S.; Malacrida, P.; Hansen, T. W.; Rossmeisl, J.; Chorkendorff, I.; Stephens, I. E. L. Nano Lett. 2014, 14, 1603.

(4) Yamanaka, I.; Onizawa, T.; Takenaka, S.; Otsuka, K. Angew. Chem. Int. Ed. 2003, 42, 3653.

(5) Yamanaka, I.; Onisawa, T.; Hashimoto, T.; Murayama, T. ChemSusChem 2011, 4, 494.

(6) Fellinger, T.-P.; Hasché, F.; Strasser, P.; Antonietti, M. J. Am. Chem. Soc. 2012, 134, 4072.

(7) Hatay, I.; Su, B.; Méndez, M. A.; Corminboeuf, C.; Khoury, T.; Gros, C. P.; Bourdillon, M.; Meyer, M.; Barbe, J.-M.; Ersoz, M.; Záliš, S.; Samec, Z.; Girault, H. H. J. Am. Chem. Soc. 2010, 132, 13733.

(8) Wu, S.; Su, B. Chem. Eur. J. 2012, 18, 3169.

(9) Savéant, J.-M. Chem. Rev. 2008, 108, 2348.