氮掺杂石墨烯负载双金属分解甲醇制氢的密度泛函理论研究

Density Functional Theory Study on Nitrogen-Doped Graphene-Supported Bimetallic Catalysts for Hydrogen Production via Methanol Decomposition

中文关键词:  甲醇分解制氢  石墨烯  双金属  密度泛函理论

英文关键词:Methanol decomposition for hydrogen production  Graphene  Bimetallic catalysts  Density functional theory

中文摘要:

      甲醇催化裂解制氢是氢能储运的重要环节。本文基于密度泛函理论计算，研究了甲醇在氮掺杂石墨烯负载七种双金属催化剂（Ir-Pd、Rh-Pd、Ru-Pd、Ni-Pd、Ni-Ni、Pd-Pd、Ru-Ru）表面的吸附特性及分解路径。计算结果表明，甲醇吸附时，分子的羟基氢与表面金属成键，其中Ru-Pd催化剂对甲醇的吸附能最强（-0.83 eV），显著优于其他体系。在氮掺杂石墨烯负载Ru-Pd上的甲醇分解反应存在两条路径：CH2OH*路径（先断裂O-H键再断裂C-H键）和CH3O*路径（先断裂C-H键再断裂O-H键）。两条路径的决速步骤均为初始步骤，CH3O*路径的决速步骤能垒为1.31 eV，低于CH2OH*路径的1.46 eV，表明CH3O*路径更利于甲醇分解制氢反应的发生。

英文摘要:

      Methanol catalytic decomposition for hydrogen production is a critical process for hydrogen energy storage and transportation. This study investigates the adsorption characteristics and decomposition pathways of methanol on seven bimetallic catalysts (Ir-Pd, Rh-Pd, Ru-Pd, Ni-Pd, Ni-Ni, Pd-Pd, Ru-Ru) supported on nitrogen-doped graphene using density functional theory (DFT) calculations. The computational results reveal that during methanol adsorption, the hydroxyl hydrogen of methanol bonds with surface metal atoms, with the Ru-Pd catalyst exhibiting the strongest adsorption energy (-0.83 eV), significantly outperforming other systems. Two distinct decomposition pathways were identified for methanol on the Ru-Pd/N-doped graphene system: the CH2OH* pathway (involving sequential cleavage of the O?H bond followed by the C?H bond) and the CH3O* pathway (featuring initial C?H bond rupture prior to O?H bond dissociation). Both pathways share the initial step as the rate-determining step. The energy barrier of the rate-determining step for the CH3O* pathway (1.31 eV) is notably lower than that of the CH2OH* pathway (1.46 eV), indicating the CH3O* pathway is more favorable for methanol decomposition toward hydrogen production.