Abstract Electrochemical experiments and first-principle calculations were conducted in this study to investigate the impact of carbon doping on the adsorption and absorption on Fe-C alloy surfaces. The generalized Iyer-Pickering-Zawenzaden model was adopted to determine the kinetics related to hydrogen adsorption/absorption. Discharge rate constant k1 was found increased with the presence of carbon, suggesting the promotion of the H2O ionization process and more hydrogen atoms were generated on the surface. Meanwhile, the recombination rate constant k2 decreased on carbon doping surface, indicating recombination process of hydrogen atoms were inhibited. Results also showed the hydrogen surface coverage dropped with increasing carbon content. Additionally, EIS results indicate that the distance between the adsorbed hydrogen atoms and the sample surfaces is reduced by carbon doping. All experimental results are in accordance with the first-principle calculation results which demonstrate that the presence of carbon elevated the binding energy for hydrogen adsorption while lowering the energy barrier for diffusion. Thus, carbon solutes reduce the stability for hydrogen atoms to adsorb on the surface and facilitate their diffusion into the bulk.

中文翻译：

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碳对Fe-C合金表面吸氢和吸附的影响

摘要 本研究通过电化学实验和第一性原理计算研究了碳掺杂对Fe-C合金表面吸附吸附的影响。采用广义的 Iyer-Pickering-Zawenzaden 模型来确定与氢吸附/吸收相关的动力学。发现随着碳的存在，放电速率常数 k1 增加，表明促进了 H2O 电离过程，并在表面产生了更多的氢原子。同时，碳掺杂表面的复合速率常数 k2 降低，表明氢原子的复合过程受到抑制。结果还显示氢表面覆盖率随着碳含量的增加而下降。此外，EIS 结果表明，碳掺杂减少了吸附氢原子与样品表面之间的距离。所有实验结果均符合第一性原理计算结果，表明碳的存在提高了氢吸附的结合能，同时降低了扩散的能垒。因此，碳溶质降低了氢原子吸附在表面上的稳定性并促进它们扩散到本体中。