To achieve the ambitious goals of a hydrogen society, understanding how hydrogen interacts with materials is crucial.
Overcoming the limitations of existing observation methods, Assistant Professor Hiroshi Kakinuma and his team at Tohoku University’s Institute of Materials Research have introduced a cost-effective technique to capture dynamic images of hydrogen flow within metals. This revolutionary method employs polyaniline, a color-changing polymer, and a standard optical microscope, offering unprecedented spatial and temporal resolutions.
Polyaniline, undergoing color changes in response to hydrogen, facilitates the visualization of hydrogen distribution in metals. The optical microscope, coupled with this polymer, allows for micro-scale videos across a broad sub-millimeter field. This surpasses traditional methods, enabling a comprehensive view of hydrogen behavior with superior resolutions.
In a study focusing on pure nickel foil, hydrogen diffusion was tracked. Concentration gradients propelled hydrogen through the foil, reaching the side coated with polyaniline. The color shift from purple to white in polyaniline, observable through the microscope, provided insights into hydrogen movement within nickel. Remarkably, it was unveiled that hydrogen predominantly diffused through crystal grain boundaries, emphasizing the influence of nickel atom arrangements.
The research highlighted variations in hydrogen diffusion based on crystal grain boundary types. The study indicated that hydrogen atom movement in pure nickel correlates with the arrangement of nickel atoms. Larger geometric spaces in grain boundaries facilitate increased hydrogen flow. This groundbreaking insight establishes a link between atomic-level structural features of metals and hydrogen behavior.
The newly developed hydrogen observation method is versatile, applicable to any metal. This breakthrough promises to experimentally unveil the intricate relationship between various metals’ structures and hydrogen behavior, moving beyond theoretical simulations. Understanding the causal link between atomic-level metal structures and microscale hydrogen dynamics opens avenues for efficient material design.
