介观结构氮掺杂碳纳米笼负载铂-钌合金催化剂的优异甲醇电氧化性能

Alloyed Pt–Ru Nanoparticles Immobilized on Mesostructured Nitrogen-Doped Carbon Nanocages for Efficient Methanol Electrooxidation

利用氮掺杂碳纳米笼(h NCNC)的高比表面积及掺杂氮原子的锚定作用,方便地将约3 nm的Pt-Ru合金纳米粒子均匀地负载在h NCNC表面,制得了Pt和Ru比例可调的Pt-Ru/h NCNC双金属合金催化剂.这些催化剂展现出优异的甲醇催化氧化活性和稳定性,且具有良好的抗CO中毒能力,显著优于Pt/h NCNC和商业Pt Ru/C等对照组催化剂.其优异的电化学性能可归因于以下因素的协同作用:(1)Pt-Ru合金的双功能机制增强了催化剂的CO氧化脱附能力从而使活性位重新暴露,(2)h NCNC的氮掺杂及高比表面积有利于获得粒径小且均匀的合金纳米粒子,(3)h NCNC的多尺度分级孔结构有利于甲醇等参与反应物质的传输.

Direct methanol fuel cells （DMFC） have attracted extensive attention as ideal candidates for automotive and portable applications owing to the fascinating advantages such as high conversion efficiency, environmental friendliness, safety, wide sources of methanol, and simple cell structure. Electrocatalysts are one of crucial factors limiting the perfor- mance of DMFC. Nowadays, precious Pt-based catalyst, in spite of costliness and scarcity, is the most popular catalyst for methanol oxidation reaction （MOR） at anode due to the much better performances than those of the non-Pt catalysts. But there exists some shortcomings such as poor CO-tolerance and durability. Pt alloying with other metals, e.g. Ru, is an effective strategy to improve the catalytic performance. In addition, the support with a large specific surface area （SSA）, high conductivity and suitable porous structure, such as sp2 carbon, could lead to high dispersion, high utilization and stability of Pt-based nanoparticles, also favorable for MOR. Recently, by in situ MgO template method, we reported the unique 3D hier-archical carbon-based nanocages featured with ultrahigh SSA, micro-meso-macro-pore coexistence, good conductivity and easy doping, which exhibited excellent electrochemical performances. Herein, taking the advantages of nitrogen-dopant anchoring ftmction and unique mesostructures of hierarchical N-doped carbon nanocages （hNCNC）, we report the Pt-Ru etec-trocatalysts immobilized on hNCNC （Pt-Ru/hNCNC） prepared via modified microwave-assisted ethylene glycol （EG） reduction method. The so-constructed Pt-Ru/hNCNC catalysts with ca. 30 wt% loading and tunable atomic ratio of Pt to Ru have a highly homogeneous dispersion of metal nanoparticles with the average size of ca. 3 rim. The alloying Pt-Ru/hNCNC catalysts demonstrate good CO-tolerance, high MOR activity and durability, superior to those of the counterparts of Pt/hNCNC and commercial PtRu/C. The good electrochemical performance can be ascribed to the synergistic effects of the bifunctional effect due to introduction of Ru, small size and high dispersion of metal nanoparticles induced by the large SSA and nitrogen participation of hNCNC, and multi-scaled hierarchical pore structures beneficial to the mass transportation. These results proposed a potential strategy to develop the high-performance Pt-based MOR catalysts based on the novel mesostructured hNCNC.