Catalysis, electrocatalysis and electrochemical promotion of the steam reforming of methane over Ni film and Ni-YSZ cermet anodesCatalysis, electrocatalysis and electrochemical promotion of the steam reforming of methane over Ni film and Ni-YSZ cermet anodes Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2015-10-301995enThe kinetics of the steam reforming reaction of CH4 were investigated at temperatures 750 to 950°C under both open-circuit and closed-circuit conditions on Ni-YSZ (Yttria Stabilized Zirconia) solid oxide fuel cell (SOFC) anodes and polycrystalline Ni film SOFC anodes of measured Ni surface area. It was found that the rate of methane reforming on the Ni surface exhibits a Langmuir-Hinshelwood type dependence onPCH4 andPH2O which results from competitive adsorption of carbonaceous species and oxygen or OH. Consequently the rate is maximized for intermediatePCH4 toPH2O ratios. The reaction kinetics are affected significantly by cell current and potential under closed-circuit conditions. Over a rather wide range of operating conditions the observed rate changes are Faradaic, which implies negligible variation in the catalytic properties of the Ni surface with potential. At lower temperatures, however, and particularly under conditions of carbon deposition, the rates of CO, H2, CO2 and, more importantly, carbon formation exhibit pronounced non-Faradaic (NEMCA), or electrochemical promotion, behaviour. Some non-Faradaic behaviour is also observed for higher H2O to CH4 ratios but in this case the effect of applied potential is reproducible but not readily reversible.http://creativecommons.org/licenses/by/4.0/Ionics15-6491-498 Gentekakis Ioannis Γεντεκακης Ιωαννης Jiang Yi Neophytides, S. G Bebelis, Symeon Vayenas, Costas G Springer Verlag Catalysis Electrocatalysis