The present invention relates to a metallic bipolar plate comprising a
metal substrate and at least one layer of a non-hydrogenated
transition metal-doped
diamond-like carbon (DLC) provided on the
metal substrate, wherein the non-hydrogenated DLC comprises at least one
transition metal selected from groups 4d, 5d and 6d of the
periodic table of elements and a part of the at least one
transition metal is present in the form of
carbide of the at least one transition
metal in the non-hydrogenated DLC as a matrix. The non-hydrogenated transition metal-doped DLC has an
indentation hardness of ≥35 GPa, preferably of ≥40 GPa. The metal-doped DLC used as a
coating of metallic bipolar plates in
fuel cells and electrolyzers exhibits high
corrosion resistance and low interface
contact resistance even for longer lifetimes (>10,000 hours) and harsh operational conditions. Therefore, the present invention also pertains to such uses, and also to
fuel cells, in particular
proton exchange membrane
fuel cells, and electrolyzers comprising such coated metallic bipolar plates. Further, the present invention provides a cathodic arc
discharge deposition method for depositing a
coating of non-hydrogenated DLC comprising at least one of the above-mentioned transition metals, which is preferably the non-hydrogenated transition metal-doped DLC.