【摘要】 基于密度泛函理论，研究了Ca₂B₄团簇的几何结构、电子特征和储氢性能。前2个与第4个能量最低构型Ca₂B₄01、Ca₂B₄02和Ca₂B₄04有很高的热力学稳定性，分别最多可以吸附12、12和10个氢分子，达到16.3%、16.3%和14.0%的储氢量，超过了美国能源部提出的目标（5.5%）。Ca₂B₄01（H₂）₁₂、Ca₂B₄ 02（H₂）₁₂和Ca₂B₄ 04（H₂）₁₀的平均每个氢分子吸附能量分别为0.58～4.21 eV、0.54～3.69 eV和0.10～0.12 eV。玻恩-奥本海默分子动力学模拟表明，Ca₂B₄ 01和Ca₂B₄ 02可作为潜在吸附氢气的候选目标，而Ca₂B₄ 04不行。吉布斯自由能校正的氢吸附能结果表明，在101 325 Pa下，Ca₂B₄ 01和Ca₂B₄ 02吸附12个氢气分子有较大的可调节的温度范围。更多还原

【Abstract】 The structural feature and electronic property of Ca₂B₄, as well as its potential for hydrogen storage, have been studied using density functional theory. The first, second, and fourth low-lying isomers Ca₂B₄ 01, Ca₂B₄02, and Ca₂B₄ 04 have high stabilities in thermodynamics and can adsorb 12, 12, and 10 H₂ molecules with respective H₂ gravimetric uptake capacity of 16.3%, 16.3%, and 14.0%, which far exceeds the target（5.5%） proposed by the US department of energy（DOE）. The average absorption energies per H₂ molecule are in the range of 0.58-4.21 eV for Ca₂B₄01（H₂）₁₂, 0.54-3.69 eV for Ca₂B₄02（H₂）₁₂, and 0.10-0.12 eV for Ca₂B₄ 04（H₂）₁₀. Born-Oppenheimer molecular dynamic（BOMD） simulations indicate Ca₂B₄ 01 and Ca₂B₄02 are promising candidates for adsorbing hydrogen, but Ca₂B₄04 is not. The results of hydrogen adsorption energies with Gibbs free energy correction indicate that 12 H₂ molecules on Ca₂B₄ 01 and Ca₂B₄ 02 are energetically favorable with a wide range of temperatures at 101 325 Pa.更多还原