Polymer electrolyte fuel cells hold great potential for stationary and mobile applications due to high power density and low operating temperature. However, the structural changes during electrochemical reactions are not well understood. In this article, we detail the development of the sample holder equipped with gas injectors and electric conductors and its application to a membrane electrode assembly of a polymer electrolyte fuel cell. Hydrogen and oxygen gases were simultaneously sprayed on the surfaces of the anode and cathode catalysts of the membrane electrode assembly sample, respectively, and observation of the structural changes in the catalysts were simultaneously carried out along with measurement of the generated voltages.

In this study, the density functional theory (DFT) and Monte Carlo (MC) simulations were conducted to determine the equilibrium conformation of Pt2Ru3 nanoparticles with diameters 1.0–3.5 nm at finite temperature. DFT calculations were carried out to estimate the binding energy using slab configurations and energy could be correlated with some structural descriptors and multilinear regression equations to calculate the binding energy from descriptors related to the number of a specific bond to neighboring atoms. MC simulations were carried out to obtain the equilibrium conformation of atoms in Pt2Ru3 at 150–363 K. MC simulations’ result shows that atoms of the same element tend to segregate each other, and Pt/Ru ratio on the surface increases with increasing particle size; also, most of the Pt are located on the surface whereas most of the Ru are located on the subsurface or at the core sites. It is qualitatively exhibited that the Pt/Ru ratio on the surface decreases with increasing temperature.

This paper presents a periodic density functional theory study on the adsorption of H, CO, and OH on Pt2Ru3 alloy surfaces containing different conformations of Pt and Ru atoms. The results show that for separate adsorption, H is preferentially adsorbed at Pt sites, whereas CO and OH are preferentially adsorbed at Ru sites. The adsorption strengths of H, CO, and OH are affected by ratio of the alloying atoms in top surface, the nature of the neighboring atom nearest to the adsorption site, and the conformation of alloying atoms in subsurface. We also investigated the coadsorption of CO with OH and the coadsorption of CO with H and found that the Pt–CO bond strength weakens. We also uncovered some information about the competitive adsorption behavior of adsorbates (CO, OH) with the aim of designing CO-tolerant Pt–Ru alloy catalysts.

Water management is a key to ensuring high performance and durability of polymer electrolyte fuel cell (PEFC), and it is important to understand the behavior of liquid water in PEFC. In this study, the two-phase lattice Boltzmann method is applied to the simulations of water discharge from gas diffusion layers (GDL) to gas channels. The GDL is porous media composed of carbon fibers with hydrophobic treatment, and the gas channels are hydrophilic micro-scale ducts. In the simulations, arbitrarily generated porous materials are used as the structures of the GDL. We investigate the effects of solid surface wettabilities on water distribution in the gas channels and the GDL. Moreover, the results of X-ray computed tomography images in the operating PEFC are compared with the numerical simulations, and the mechanism of the water transport in PEFC is considered.