钇掺杂C $_{24}$富勒烯作为高容量可逆储氢材料的探索：DFT研究
Exploring yttrium doped C$_{24}$ fullerene as a high-capacity reversible hydrogen storage material: DFT investigations
摘要：
采用密度泛函理论研究了钇修饰的C $_{24}$富勒烯的储氢性能。单Y原子在C $_{24}$富勒烯上可可逆吸附最多6个H $_2$分子，平均吸附能为-0.37 eV，平均脱附温度为477 K，适合于燃料电池应用。氢的重量含量为8.84%，超过了美国能源部（DoE）规定的6.5wt%H的目标值。Y原子与C $_{24}$富勒烯的结合能为-3.4 eV，这是由于Y-4d和Y-5s轨道向C $_{24}$富勒烯的C-2 p轨道的电荷转移所致. H $_2$分子与Y原子的相互作用是由于Kubas型相互作用，涉及从金属d轨道到H 1 s轨道的电荷捐赠，以及导致H-H键长轻微延长的反馈捐赠。通过从头计算分子动力学模拟证实了体系在最高脱附温度下的稳定性，并通过计算Y原子运动的扩散能垒研究了金属-金属团簇的形成。我们已经纠正了所有的范德华力（VDW）相互作用的计算能量，通过应用色散能量校正，除了GGA交换相关功能的贡献。C $_{24}$ +Y系统在室温下是稳定的，并且在最高脱附温度下，足够的扩散能垒的存在防止金属-金属聚集。此外，H $_2$的结合能在DoE的目标值内（-0.2-0.7 eV/H $_2$），而H $_2$吸收（8.84% H）高于DoE的标准。因此，我们建议Y修饰的C $_{24}$富勒烯可以作为一个实际可行的潜在的储氢候选人。
英文摘要：
By employing the state-of-the-art density functional theory, we report the hydrogen storage capability of yttrium decorated C$_{24}$ fullerene. Single Y atom attached on C$_{24}$ fullerene can reversibly adsorb a maximum number of 6 H$_2$ molecules with average adsorption energy -0.37 eV and average desorption temperature 477 K, suitable for fuel cell applications. The gravimetric weight content of hydrogen is 8.84 %, which exceeds the target value of 6.5 wt % H by the department of energy (DoE) of the United States. Y atom is strongly bonded to C$_{24}$ fullerene with a binding energy of -3.4 eV due to a charge transfer from Y-4d and Y-5s orbitals to the C-2p orbitals of C$_{24}$ fullerene. The interaction of H$_2$ molecules with the Y atom is due to the Kubas type interaction involving a charge donation from the metal d orbital to H 1s orbital, and back donation causing slight elongation of H-H bond length. The stability of the system at the highest desorption temperature is confirmed by ab-initio molecular dynamics simulations, and the metal-metal clustering formation has been investigated by computing the diffusion energy barrier for the movement of Y atoms. We have corrected all the calculated energies for the van der Waals (vdW) interactions by applying the dispersion energy corrections, in addition to the contribution of the GGA exchange-correlation functional. The C$_{24}$+Y system is stable at room temperature, and at the highest desorption temperature, the presence of a sufficient diffusion energy barrier prevents metal-metal clustering. Furthermore, binding energies of H$_2$ are within the target value by DoE (-0.2-0.7 eV/H$_2$ ), while H$_2$ uptake (8.84 % H) is higher than DoE's criteria. Therefore, we propose that Y decorated C$_{24}$ fullerene can be tailored as a practically viable potential hydrogen storage candidate.
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