Hydrogen electrolyzers split water into hydrogen and oxygen, but their materials differ with the electrolyte and operating environment. Nickel foam is studied as a porous electrode substrate, particularly in alkaline systems. Its usefulness depends on the complete electrode design.
Three electrolysis routes
- Liquid alkaline electrolysis: hydroxide ions move through an alkaline electrolyte between the electrodes.
- Proton exchange membrane (PEM) electrolysis: a polymer membrane carries protons between the oxygen-producing and hydrogen-producing sides.
- Solid oxide electrolysis: a ceramic electrolyte operates at elevated temperature, using steam and electrical energy.
The U.S. Department of Energy’s electrolysis overview explains these different reaction pathways. A material used in one route should not be assumed suitable for another route or for both sides of a cell.
What nickel foam contributes
Nickel foam provides an interconnected metallic framework with pores through its thickness. It can provide a surface for an electrode coating and a path for electrical current. Research on conductive substrates in alkaline water splitting also shows that the nickel surface can participate in the measured electrochemical response.
This makes surface condition important. Results from a treated or catalyst-coated foam describe that prepared electrode and its test conditions. They are not automatically the performance of an untreated commercial foam sheet.
Pore structure and gas removal
A foam electrode contains spaces for electrolyte and evolving gas. The available surface and the movement of gas through that space both affect how the electrode behaves in a cell.
Bleeker and colleagues’ bubble-removal research found substantial bubble-related resistance in the foam electrodes they tested. This provides a useful example of the trade-off: more internal surface does not by itself guarantee lower cell losses.
Related nickel materials
HuiRui’s nickel foam for water electrolyzer projects and nickel foam range provide product information. For the separate question of changing power input, see our guide to renewable-powered electrolysis and operating conditions.