Amorphous (ErAlCrZrTi)O High‐Entropy Nanofilms for Highly Efficient Hydrogen Embrittlement Prevention

Abstract Hydrogen embrittlement in metals seriously threatens the safe and durable operation of hydrogen energy. Developing efficient and robust hydrogen barriers is a viable solution to solve this issue but remains a significant challenge. An amorphous (ErAlCrZrTi)O high‐entropy nanofilm is successfully fabricated via sol‐gel on steel and identified as highly efficient and robust hydrogen barrier. At 270 nm thickness, the nanofilm achieves ultra‐low hydrogen permeability of 1.35 × 10 ⁻¹⁵ mol m ⁻¹ s ⁻¹ Pa ^−0.5 , enhancing hydrogen resistance by 2738 times at 500 °C compared with that of bare steel. Compared to Er ₂ O ₃ , Al ₂ O ₃ , Cr ₂ O ₃ , and ZrO ₂ , it improves hydrogen resistance by 5, 11, 26, and 90 times, respectively. Moreover, such a high hydrogen resistance can be satisfyingly retained even after the (ErAlCrZrTi)O nanofilm suffering 10 dpa irradiation. The nanofilm exhibits 37 MPa bonding strength and exceptional thermal shock resistance, attributed to the formation of Cr₂O₃ transition layer via precipitation and oxidation of Cr from the substrate during annealing. It strengthens adhesion and alleviates thermal expansion mismatch with the substrate. The mechanism for the high barrier efficiency is further revealed by this theoretical calculations. These results provide tremendous insights on the understanding and future design of high‐performance hydrogen barriers for hydrogen embrittlement prevention.