Electrocatalytic nitrate and nitrous oxide reduction at interfaces between Pt-Pd nanoparticles and fluorine-doped tin oxide

Abstract

We report the preparation of Pt and/or Pd nanoparticle-deposited fluorine-doped tin oxide (FTO) electrodes by an arc-plasma deposition (APD) technique and their electrocatalytic activity for nitrate (NO3–), nitrite (NO2–), nitric oxide (NO), and nitrous oxide (N2O) reduction reactions in acidic media. Cyclic voltammetry of the electrodes revealed that the co-presence of Pt and Pd on FTO showed higher catalytic activity than Pt or Pd on FTO for the NO3– reduction reaction, where the PtPd/Sn interface acts as the catalytic active site. The PtPd/Sn interface also showed higher catalytic activity for the N2O reduction reaction to dinitrogen than the Pt/Sn or Pd/Sn interfaces, whereas it showed no drastic contribution to the electrocatalytic NO2– and NO reduction reactions. Because the NO3– and N2O reduction reaction occur in the potential region of hydrogen adsorption on Pt and Pd electrodes, the PtPd/Sn interface could enhance NO3– and N2O adsorption and/or suppress the hydrogen adsorption. Our findings will be useful for the design of interfaces between noble metal mixture/alloy nanoparticles and Sn, leading to the practical application of denitrification to harmless dinitrogen.