  Hydrogen fuel cells offer a clean and sustainable energy conversion solution.
The bipolar separator plate, a critical component in fuel cells, plays a vital
role in preventing reactant gas cross-contamination and facilitating efficient
ion transport in a fuel cell. High chromium ferritic stainless steel with an
artificially formed thin chromium oxide passive film has recently gained
attention due to its superior electrical conductivity and corrosion resistance,
making it a suitable material for separators. In this study, we investigate the
microscopic electrical conductivity of the intrinsic passive oxide film on such
ferritic stainless steel. Through advanced surface characterization techniques
such as current sensing atomic force microscopy and scanning tunneling
microscopy/spectroscopy, we discover highly conductive regions within the film
that vary depending on location. These findings provide valuable insights into
the behavior of the passive oxide film in fuel cells. By understanding the
microscopic electrical properties, we can enhance the design and performance of
separator materials in hydrogen fuel cells. Ultimately, this research
contributes to a broader understanding of separator materials and supports the
wider application of hydrogen fuel cells.
