An atomic-scale view at Fe4N as hydrogen barrier material

TL;DR

This study demonstrates that Fe4N nitride layers significantly reduce hydrogen diffusion in metals, offering a cost-effective and scalable solution to prevent hydrogen embrittlement in structural materials.

Contribution

The paper introduces Fe4N as an effective hydrogen barrier material, combining experimental and theoretical methods to quantify its diffusion reduction capabilities.

Findings

Hydrogen diffusion is reduced by a factor of 20 at room temperature.

Fe4N creates energetically unfavorable states for hydrogen, hindering permeation.

The material is cost-efficient and suitable for large-scale applications.

Abstract

Hydrogen, while a promising sustainable energy carrier, presents challenges such as the embrittlement of materials due to its ability to penetrate and weaken their crystal structures. Here we investigate Fe4N nitride layers, formed on iron through a cost-effective gas nitriding process, as an effective hydrogen permeation barrier. A combination of screening using advanced characterization, density functional theory calculations, and hydrogen permeation analysis reveals that a nitride layer reduces hydrogen diffusion by a factor of 20 at room temperature. This reduction is achieved by creating energetically unfavorable states due to stronger H-binding at the surface and high energy barriers for diffusion. The findings demonstrate the potential of Fe4N as a cost-efficient and easy-to-process solution to protecting metallic materials exposed to hydrogen, with great advantages for large-scale applications.