Highly Dispersed Pd-CeO2 Nanoparticles Supported on N-Doped Core Shell Structured Mesoporous Carbon for Methanol Oxidation in Alkaline Media
Highly Dispersed Pd-CeO2 Nanoparticles Supported on N-Doped Core Shell Structured Mesoporous Carbon for Methanol Oxidation in Alkaline Media
复制标题
N掺杂核壳结构介孔碳负载的高度分散的Pd-CeO2纳米粒子用于碱性介质中的甲醇氧化
DOI：
10.1021/acscatal.9b00726
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发表时间：
2019-07-01
期刊：
影响因子：
12.9
通讯作者：
Wu, Gang
中科院分区：
文献类型：
--
作者：
Tan, Qiang;Shu, Chengyong;Wu, Gang
直接甲醇燃料电池（DMFC）阳极甲醇氧化反应（莫尔）的缓流动力学主要是由于贵金属催化剂的吸附CO中毒。已知CeO 2向相邻的贵金属位点提供含氧物质以促进在莫尔期间的CO去除。在这项工作中，高度分散的Pd纳米粒子周围的CeO 2点沉积在核壳结构和氮掺杂的介孔碳球（NMCS）的支持，表现出令人鼓舞的电催化活性，CO耐受性，和稳定性的莫尔在碱性介质中。发现Pd与CeO 2的比例对于整体催化性能的增强至关重要。当与商业PtRu/C催化剂相比时，优化的Pd-（20%）-CeO 2（20%）/NMCS催化剂表现出相当的CO汽提起始电位，类似于6倍高的峰值电流密度，以及增强的循环稳定性。氮掺杂的独特介孔碳也有利于Pd纳米颗粒和CeO 2点的均匀分散。密度泛函理论计算结果表明，Pd与CeO 2之间的强电子相互作用以及载体中的氮掺杂显著降低了CO在Pd表面的吸附能，从而提高了Pd-CeO 2/NMCS催化剂的CO耐受性，进一步提高了莫尔还原活性。使用基于聚合物纤维膜的碱性DMFC，当NiCo 2 O 4催化剂用于氧阴极时，Pd-（20%）-CeO 2（20%）/NMCS阳极催化剂进一步表现出令人鼓舞的性能。
Sluggish kinetics of the methanol oxidation reaction (MOR) at the anode of direct methanol fuel cells (DMFCs) is primarily due to adsorbed CO poisoning of precious metal catalysts. CeO2 is known to provide oxygen containing species to adjacent precious metal sites for facilitating CO removal during the MOR. In this work, highly dispersed Pd nanoparticles surrounded by CeO2 dots were deposited on a core-shell structured and nitrogen-doped mesoporous carbon sphere (NMCS) support, which exhibited encouraging electrocatalytic activity, CO tolerance, and stability for the MOR in alkaline media. The ratios of Pd to CeO2 were found crucial for overall catalytic performance enhancement. When compared to a commercial PtRu/C catalyst, an optimized Pd-(20%)-CeO2(20%)/NMCS catalyst presented a comparable CO stripping onset potential, similar to 6 times higher peak current density, and enhanced cyclic stability. The unique mesoporous carbon with nitrogen doping also benefits for uniform dispersion of Pd nanoparticles and CeO2 dots. In good agreement with experimental spectroscopy analysis, density functional theory calculations suggest that the strong electronic interactions between Pd and surrounding CeO2, as well as nitrogen dopants in supports, dramatically reduce the adsorption energy of CO at the Pd surface, therefore enhancing CO tolerance of the Pd-CeO2/NMCS catalyst and further improving MOR activity. Using a polymer fiber membrane-based alkaline DMFC, the Pd-(20%)-CeO2 ((20%))/NMCS anode catalyst further demonstrated encouraging performance when a NiCo2O4 catalyst was used for the oxygen cathode.