Combining Transition Metals – An Approach towards High-Performing Coking Tolerant Solid Oxide Fuel Cell Anodes

Abstract

Bimetallic combinations of the three transition metals, Ni, Co, and Fe, were infiltrated alongside gadolinium doped ceria (CGO), into a strontium titanate backbone. The infiltrated cells were analyzed using electrochemical impedance spectroscopy in the temperature range 650°-850°C and in the atmospheres: 4% H2O/H2, 50% H2O/H2, 80% H2O/H2, and 50% CO2/CO. In addition, in situ synchronous Raman spectroscopy and EIS experiments were performed to explore the coking tolerance of the bimetallic infiltrations. The electrocatalytic activity of the bimetals were similar to the single metals with electrode area specific resistances 0.35 Ωcm 2 , 0.28 Ωcm 2 , and 1.32 of Ωcm 2 for the Co-Fe-CGO, Ni-Co-CGO, and Ni-Fe-CGO infiltrated cells, respectively, at 750 o C in 50% H2O/H2. The results obtained from the synchronous in situ Raman -EIS experiments further indicates an improved coking resistance for combined transition metal infiltrations.

Operando characterization of metallic and bimetallic electrocatalysts for SOFC fuel electrodes operating under internal methane reforming conditions

“…The data illustrate how the inltrated nanoparticles tended to agglomerate into larger particles during SOFC operation, a result consistent with prior literature reports. 15,17,32 This behavior was common to all inltrates used in these studies and resulted in spherical nanoparticles of 100-200 nm diameters aer operation. Some separation of the metal inltrates from the CGO was also observed.…”

“…16 Adding CGO into the structural matrix has successfully decreased the polarization resistance of these STN electrodes in the symmetrical cell conguration. 17 The studies described below investigated the electrochemical performance of inltrated STN based fuel electrodes in fully functional SOFCs. The STN-based fuel electrodes were inltrated with CGO and either nickel or cobalt as Ni-CGO, Co-CGO, or Ni-Co-CGO.…”

The promoting effect of Fe on Ni/ GDC for the Solid Oxide H 2 O electrolysis

“…Another interesting application of Fe (1 and 40 wt%) and Ni (5‐10 wt%) combination with GDC was reported by Simonsen et al, 33 who characterized this formulation as a potential fuel electrode for metal‐supported SOFC/SOECs. Furthermore, small amounts of NiO (~1 wt%) and FeO (~1 wt%) co‐infiltrated on a Sr 0.94 Ti 0.9 Nb 0.1 O 0.3 (STN94) backbone were studied by Drasbæk et al 34 either in the absence of GDC under 4% H 2 O/H 2 and 50% H 2 O/H 2 mixtures, or in the presence of GDC 35 under 4% H 2 O/H 2 , 50% H 2 O/H 2 and 50% CO 2 /CO.…”