A comprehensive review on PEM water electrolysis

This paper, the first in a series of four review papers, presents a brief summary of the fundamental properties and characteristics of ionic polymeric-metal composites (IPMCs) as biomimetic sensors, actuators and artificial muscles. The forthcoming three review papers, to follow this paper, will address in detail such fundamentals and, in particular, manufacturing techniques and the electronic and electromechanical characteristics of IPMCs (part II), the phenomenological modelling of the underlying sensing and actuation mechanisms in IPMCs (part III) and the potential application areas for IPMCs (part IV). This paper is a summary of all recent findings and current state-of-the art manufacturing techniques, phenomenological laws and mechanical and electrical characteristics. A number of methodologies in developing high-force-density IPMCs are also reported.

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Ionic polymer-metal composites: I. Fundamentals

This paper reviews water electrolysis technologies for hydrogen production and also surveys the state of the art of water electrolysis integration with renewable energies. First, attention is paid to the thermodynamic and electrochemical processes to better understand how electrolysis cells work and how they can be combined to build big electrolysis modules. The electrolysis process and the characteristics, advantages, drawbacks, and challenges of the three main existing electrolysis technologies, namely alkaline, polymer electrolyte membrane, and solid oxide electrolyte, are then discussed. Current manufacturers and the main features of commercially available electrolyzers are extensively reviewed. Finally, the possible configurations allowing the integration of water electrolysis units with renewable energy sources in both autonomous and grid-connected systems are presented and some relevant demonstration projects are commented.

Hydrogen Production From Water Electrolysis: Current Status and Future Trends

New structures for the Pt/C catalyst layer of polymer electrolyte fuel cell electrodes have been developed that substantially increase the utilization efficiency of the catalyst. Fabricating the catalyst layers and gas diffusion backings separately makes it possible to formulate each structure with the properties that are most suitable for its function. In the case of the catalyst layer, the optimal properties are hydrophilicity, thinness, uniformity, and the proper ratio of ionomer and supported catalyst. The catalyst layers are cast from solution as thin films that utilize the ionomer itself as a binder. The thin films are hot pressed directly onto the ionomer membranes, and the hydrophobic gas diffusion backings are inserted when the cells are assembled. The performances of fuel cells based on the thin film catalyst layers are comparable with those of gas diffusion electrode designs that utilize several times as much platinum, thus the specific activities of the Pt catalysts in the new structures are significantly higher.

Thin-film catalyst layers for polymer electrolyte fuel cell electrodes

This paper, the second in a series of four review papers to appear in this journal, presents a detailed description of various techniques and experimental procedures in manufacturing ionic polymer–metal composites (IPMCs) that, if fully developed, can be used as effective biomimetic sensors, actuators and artificial muscles as well as fully electroded with embedded electrodes for fuel cells. The performance of IPMCs manufactured by different manufacturing techniques are presented and compared. In particular, a number of issues such as force optimization using the Taguchi design of experiment technique, effects of different cations on electromechanical performance of IPMCs, electrode and particle size and distribution control, manufacturing cost minimization approaches, scaling and three-dimensional (3D) muscle production issues and heterogeneous composites by physical loading techniques are also reviewed and discussed.

https://iopscience.iop.org/article/10.1088/0964-1726/12/1/308/pdf

N. Wakabayashi

Papers

Solid polymer electrolyte water electrolysis

Advanced alkaline water electrolysis