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International audience; Architecturally designed La2−xPrxNiO4+δ (with x = 0, 0.5, 1 and 2) cathodes on the Ce0.9Gd0.1O2−δ (CGO) electrolyte have been prepared with a view to take advantage of the complimentary properties of the two extreme compositions La2NiO4+δ and Pr2NiO4+δ, i.e. the superior stability of La2NiO4+δ and the higher electronic conductivity of Pr2NiO4+δ. The design consists of stacking of two layers starting with a 3D tree-like microstructure (∼20 μm thick) over a thin dense base layer (∼100 nm) fabricated in one step by electrostatic spray deposition (ESD) and then topped by using a screen-printed (SP) current collecting layer of the same composition. X-ray diffraction confirms the formation of a complete solid solution crystallizing in a single phase orthorhombic structure with the Fmmm space group. The thermodynamic stability and polarisation resistance (Rpol) decrease by increasing the Pr content. Among the complete La2−xPrxNiO4+δ solid solutions, LaPrNiO4+δ shows the best compromise between electrochemical properties (the lowest Rpol value available in the literature for this composition, 0.12 Ω cm2 at 600 °C) and thermodynamic stability in air. Moreover, an anode supported single cell (Ni-3YSZ/Ni-8YSZ/8YSZ/CGO) including the LaPrNiO4+δ double layer electrode shows a maximum power density of 438 mW cm−2 at 700 °C.

In this paper, based on a multiscale modelling framework, we focus on understanding the impact of CO adsorption on the intrinsic stability properties of PtxCoy nanoparticles under PEMFC anode operating conditions. First, CO adsorption effect on PtxCoy has been studied by using Monte Carlo (MC) simulation. Then, the MC results are coupled with an ab initio based kinetic model to simulate the effect of CO poisoning on the activity and durability of the PtxCoy nanoparticles as HOR catalysts. The results are compared with simulations carried out with pure Pt, where potential self-oscillatory behaviour is detected and experimentally confirmed. The PtxCoy HOR activity and stability reveals to be strongly dependent on the nanoparticle size and composition. For some nanoparticle sizes, simulations show that PtCo nanoparticles provide better CO tolerance than Pt3Co. CO adsorption on PtCo slows down Co dissolution in short-term operation. However, this effect is overcome by the increase of the anode potential due to CO adsorption. Thus, CO adsorption enhances Co dissolution in long-term operation. Due to this Co dissolution, the HOR activity of PtCo degrades faster than Pt3Co in long-term operation.

In this paper we discuss a comprehensive physical-based model of the PEMFC materials degradation allowing predicting the MEA durability as function of the operation conditions, initial material loadings and electrodes microstructure. The approach, build within a modular multiscale non-equilibrium thermodynamics framework, couples atomistic-based descriptions of catalyst contamination/oxidation/dissolution/ripening, dissolved catalyst migration in the ionomer, C catalyst-support corrosion and chemical PEM degradation, with the degradation-induced nano/microstructural and transport properties (of reactants and charges) evolution. By describing the feedback between the instantaneous performance and the material aging phenomena, the model provides new insights on the competition between the different degradation processes under automotive-operating conditions. The predictive capabilities of our approach are illustrated in this paper through four applicative examples: 1) PtxCoy catalysts degradation 2) competition of PEM and cathode C degradation 3) synergies between anodic CO contamination and PEM and cathode C degradation, and 4) synergies between Pt and C degradation.

Based on a multiscale modeling framework, we focus on understanding the impact of CO adsorption on the intrinsic stability properties of PtxCoy nanoparticles under PEMFC anode operating conditions. Firstly, CO adsorption effect on PtxCoy has been studied by using Monte Carlo (MC) simulation. Then, the MC results were coupled with a non-equilibrium thermodynamics kinetics model (MEMEPhys®) to simulate the effect of CO poisoning on the activity and durability of PtxCoy nanoparticles as HOR catalysts. The results are compared with simulations carried out on Pt, where potential self-oscillatory behaviour is observed and experimentally confirmed. The PtxCoy HOR activity and stability properties reveal to be strongly dependent on the nanoparticle size and composition. For certain nanoparticle sizes, simulations show that PtCo nanoparticles provide better CO tolerance than Pt3Co. However, the CO tolerance of PtCo degrades faster than that of Pt3Co in long-term operation. From both modeling and experimental approaches, it is demonstrated for the first time that this observation is due to the fact that CO adsorption enhances Cobalt dissolution.