Computational studies on fuel cell-related issues are increasingly common. These studies range from engineering level models of fuel cell systems and stacks to molecular level, electronic structure calculations on the behavior of membranes and catalysts, and everything in between. This volume explores this range. It is appropriate to ask what, if anything, does this work tell us that we cannot deduce intuitively? Does the emperor have any clothes? In answering this question resolutely in the affirmative, I will also take the liberty to comment a bit on what makes the effort worthwhile to both the perpetrator(s) of the computational study (hereafter I will use the blanket terms modeler and model for both engineering and chemical physics contexts) and to the rest of the world. The requirements of utility are different in the two spheres. As with any activity, there is a range of quality of work within the modeling community. So what constitutes a useful model? What are the best practices, serving both the needs of the promulgator and consumer? Some of the key com- nents are covered below. First, let me provide a word on my ‘credentials’ for such commentary. I have participated in, and sometimes initiated, a c- tinuous series of such efforts devoted to studies of PEMFC components and cells over the past 17 years. All that participation was from the experim- tal, qualitative side of the effort.

Device Modeling.- Section Preface.- Modeling of PEMFC Catalyst Layer Performance and Degradation.- Catalyst Layer Operation in PEM Fuel Cells: From Structural Pictures to Tractable Models.- Reactor Dynamics of PEM Fuel Cells.- Coupled Proton and Water Transport in Polymer Electrolyte Membranes.- A Combination Model for Macroscopic Transport in Polymer-Electrolyte Membranes.- Analytical Models of a Polymer Electrolyte Fuel Cell.- Phase Change and Hysteresis in PEMFCs.- Modeling of Two-Phase Flow and Catalytic Reaction Kinetics for DMFCs.- Thermal and Electrical Coupling in Stacks.- Materials Modeling.- Section Preface.- Proton Transport in Polymer Electrolyte Membranes Using Theory and Classical Molecular Dynamics.- Modeling the State of the Water in Polymer Electrolyte Membranes.- Proton Conduction in PEMs: Complexity, Cooperativity and Connectivity.- Atomistic Structural Modelling of Ionomer Membrane Morphology.- Quantum Molecular Dynamic Simulation of Proton Conducting Materials.- Morphology of Nafion Membranes: Microscopic and Mesoscopic Modeling.- Molecular-Level Modeling of Anode and Cathode Electrocatalysis for PEM Fuel Cells.- Reactivity of Bimetallic Nanoclusters Toward the Oxygen Reduction in Acid Medium.- Multi-Scale Modeling of CO Oxidation on Pt-Based Electrocatalysts.- Modeling Electrocatalytic Reaction Systems from First Principles.

Computational studies on fuel cell-related issues are increasingly common. These studies range from engineering level models of fuel cell systems and stacks to molecular level, electronic structure calculations on the behavior of membranes and catalysts, and everything in between. This volume explores this range. It is appropriate to ask what, if anything, does this work tell us that we cannot deduce intuitively? Does the emperor have any clothes? In answering this question resolutely in the affirmative, I will also take the liberty to comment a bit on what makes the effort worthwhile to both the perpetrator(s) of the computational study (hereafter I will use the blanket terms modeler and model for both engineering and chemical physics contexts) and to the rest of the world. The requirements of utility are different in the two spheres. As with any activity, there is a range of quality of work within the modeling community. So what constitutes a useful model? What are the best practices, serving both the needs of the promulgator and consumer? Some of the key com- nents are covered below. First, let me provide a word on my ‘credentials’ for such commentary. I have participated in, and sometimes initiated, a c- tinuous series of such efforts devoted to studies of PEMFC components and cells over the past 17 years. All that participation was from the experim- tal, qualitative side of the effort.