Desales Guzmán Luis Alberto, Pacheco Sánchez Juan Horacio, Arellano Peraza Juan Salvador
División de Estudios de Posgrado e Investigación, Instituto Tecnológico de Toluca, Metepec 52149, Estado de México, México.
Área de Física Atómica Molecular Aplicada, Universidad Autónoma Metropolitana Azcapotzalco, Azcapotzalco, C.P. 02200 Ciudad de México, México.
ACS Omega. 2022 Mar 16;7(12):10100-10114. doi: 10.1021/acsomega.1c06149. eCollection 2022 Mar 29.
We have studied the feasibility of activated carbyne as a good hydrogen storage material. Density functional theory (DFT) simulations through van der Waals interactions have been applied to investigate calcium sorption on activating carbyne with zinc dichloride (ZnCl) and also interactions of molecular hydrogen with pristine carbyne and Ca functionalized on an activated carbyne C-ring. The obtained results showed that (i) the chemical activation of the C-ring with ZnCl increases its area by 5.17% with respect to pristine carbyne. (ii) Ca atoms at small concentrations tend to get atomically sparse on carbyne, donating +0.94e and +1.05e to the ring, according to Mulliken population analysis and the electrostatic potential fitting charges, respectively. Furthermore, in the presence of calcium, hydrogen sorption increases by 21.8% in comparison with Ca-decorated pure carbyne. (iii) Seven hydrogen molecules per Ca atom have adsorption energy close to the range of ∼0.3-0.5 eV per H, which is necessary for effective charge/discharge cycles. (iv) Theoretical uptake (7.11 wt %) with a single Ca atom is higher than the U.S. Department of Energy target (5.5 wt %). Therefore, an activated C-ring can bind three Ca atoms with its seven H molecules reaching 13.8 wt %. (v) Equilibrium pressure for CaC-7H and CaC-21H systems (5-15 MPa) by means of adsorption isotherm calculations. The calculated van't Hoff desorption temperatures exceed considerably the boiling point of liquid nitrogen. In addition, we also performed DFT-based molecular dynamics simulations for the C, CaC, CaC-7H, and CaC-21H systems to study thermal stability. Our results confirm the potential of Ca-decorated carbyne for hydrogen storage.
我们研究了活性卡宾作为一种优良储氢材料的可行性。通过范德华相互作用进行的密度泛函理论（DFT）模拟已被用于研究用二氯化锌（ZnCl）活化卡宾时钙的吸附情况，以及分子氢与原始卡宾和在活性卡宾C环上功能化的Ca之间的相互作用。所得结果表明：（i）用ZnCl对C环进行化学活化后，其面积相对于原始卡宾增加了5.17%。（ii）根据Mulliken布居分析和静电势拟合电荷，低浓度的Ca原子在卡宾上倾向于原子级稀疏分布，分别向环贡献+0.94e和+1.05e。此外，在有钙存在的情况下，与Ca修饰的纯卡宾相比，氢吸附增加了21.8%。（iii）每个Ca原子吸附七个氢分子，其吸附能接近每个H约0.3 - 0.5 eV的范围，这对于有效的充放电循环是必要的。（iv）单个Ca原子的理论吸氢量（7.11 wt%）高于美国能源部的目标（5.5 wt%）。因此，一个活化的C环可以结合三个Ca原子及其七个H分子，达到13.8 wt%。（v）通过吸附等温线计算得出CaC - 7H和CaC - 21H体系的平衡压力（5 - 15 MPa）。计算得到的范特霍夫脱附温度大大超过液氮的沸点。此外，我们还对C、CaC、CaC - 7H和CaC - 21H体系进行了基于DFT的分子动力学模拟，以研究热稳定性。我们的结果证实了Ca修饰的卡宾在储氢方面的潜力。
