Catalytic electrooxidation of volatile organic compounds by oxygen-ion conducting ceramics in oxygen-free gas environment

Pt nanoparticles (2.5 ± 0.5 nm) deposited on yttria-stabilized zirconia (YSZ), ceria (CeO2) and samarium doped-ceria (SDC) show a strong metal support interaction (SMSI) resulting in O2 − transfer towards Pt through the triple phase boundary (tpb) and electron transfer from Pt to the ceramic. This charge transfer leads to a remarkable catalytic activity of Pt nanoparticles interfaced with ionically and mixed conductive supports for carbon monoxide and ethylene oxidation in the absence of O2 in the gas feed. It is proposed, that Pt nanoparticle and the conducting ceramic form local micro-galvanic cells, where anodic reaction is VOCs oxidation by O2 − at the tpb and the cathodic reaction is the partial reduction of zirconia or ceria. The complete electrooxidation of 909 ppm of CO and C2H4 by O2 − from the conductive ceramic support was achieved in the temperature range of 120–240 °C depending on the support. The total oxygen fraction consumed from each support per catalytic run was 1.9–2.4 and 16.9–25.9% for oxidation of 909 ppm of CO and C2H4, respectively. The catalytic activity of Pt/solid electrolytes was compared with YSZ, CeO2 and SDC blank supports and also with Pt nanoparticles deposited on non-ionically conductive carbon black (Pt/C) and γ-alumina (Pt/γ-Al2O3) supports, which all showed no catalytic activity in the absence of oxygen in the gas feed.

Figure optionsDownload as PowerPoint slideHighlights
► Electrooxidation of CO and C2H4 from the gas phase by O2 − conducting ceramics
► Pt nanoparticles on yttria-stabilized zirconia (YSZ), samarium doped-ceria (SDC) and ceria
► Formation of the local micro-galvanic cells between Pt nanoparticles and solid electrolytes
► Electrooxidation of CO and C2H4 is accompanied by partial electroreduction of solid electrolytes.
► Localized surface O2 − ionic conductivity is present in conductive ceramics at ~ 70 °C.