“Bifunctional Oxygen Electrodes for Hydrogen Production”
Project prepared for FCH-JU-2011-1, topic SP1-JTI-FCH.3.3 (Component improvement for stationary power applications).
The consortium included Newcastle University (UK), Bulgarian Hydrogen Society (Bulgaria), Narvik University College (Norway) and Newcell Technologies Ltd. (UK).
Commercial hydrogen production by water electrolysis is based on one of two technologies; aqueous alkaline electrolytes and proton exchange membrane (PEM) electrolytes. Currently the dominant (lower cost) route to hydrogen is alkaline electrolysis. Proton exchange membrane (PEM) water electrolysis systems offer advantages over traditional technologies: greater energy efficiency, higher production rates (per unit electrode area), do not require corrosive electrolytes, less operation and maintenance efforts and more compact design. Presently, there is no large scale use of PEM water electrolysis systems, with only a few commercial systems available.
The main challenge regarding widespread use in small applications is cost reduction to increase the commercial appeal of such generators. Low-price domestic electrolysers can be achieved through high production/sales volumes, but only after economical, efficient and durable prototypes have been attained. While materials originate over 70% of the stack costs, the commercially available electrode and membrane materials have not been optimised for electrolysis operation.
Although these systems are quite effective, some studies have shown that there are advantages to using rechargeable or Regenerative Fuel Cells (RFC). RFC can operate in two modes, fuel cell and electrolyzer. In fuel cell mode, hydrogen and oxygen are combined to electrical power and water. In electrolyzer mode, water is broken down into hydrogen and oxygen.
A key part of these developments can be a Bifunctional Oxygen (Air) Electrode (BOE). It would allow the RFC to replace the secondary batteries in the hybrid systems, having highest specific energy and inexpensive and environmentally benign materials. MEAs without noble and rare metals, as well as BOE have not been successfully developed up to now.
Thepresent proposal offers original ideas to overcome the challenges of BOE:
- development of Gas-Diffusion Layer from inert gas permeable particles;
- use of modern techniques like RF sputtering, chemical and physical vapour deposition and photolithography for creation of Electrocatalytic layer on GDL thus producing a
- use of alkaline membranes;
- non-noble metal catalysts.