Doping Cu Atoms Excel as the Functional Material to Tune the Wettability for TMeNs Hard Coating

Abstract The hard yet hydrophobic surface capable of withstanding harsh conditions is needed in a broad range of applications. This combined computational‐experimental study exhibits an effective modification method for transition metal nitrides protective coatings toward both excellent mechanical and robust hydrophobic properties. It indicates that the introduction of low concentrations of Cu as the solute atoms substitute for the Ta atoms in TaN lattice can form the TaCuN solid solution structure. Meanwhile, the evolution of microstructure induces the refined grains and higher H/E*, which results in a combination of improved hardness and enhanced toughness. Better yet, a moderate incorporation of solute Cu atoms into TaN structure can induce a charge depletion state and form a Cu₂O surface on TaN, as demonstrated by X‐ray photoelectron spectroscopy and electron density difference pattern. The Cu₂O phase has an essentially full Cu 3d shell achieving the coordinative saturation, which can inhibit hydrogen bonding with interfacial water molecules, succeeded in enhancing the hydrophobicity of TaN. Density functional theory calculations are further employed to clarify that hydrophobic feature of Cu₂O groups should be responsible for the tuning of wettability via destroying hydrogen‐bonding network of water molecules next to the surface.