摘要
使用旋转电极技术考察了一系列碳载金纳米颗粒(颗粒平均尺寸处在3~14nm)在碱性电解质(0.5mol/LKOH)中对氧还原反应的催化行为.随着金纳米颗粒尺寸由14nm下降至3nm,其对氧还原反应的本征活性和质量比活性均呈现持续走高趋势;但金颗粒的纳米尺寸对氧还原反应的机理及分子氧还原过程中的电子转移数目并无显著影响.使用高分辨透射电镜技术表征了金纳米颗粒的形貌,通过对金颗粒表面不同位置原子的比例进行估算,发现金颗粒表面高能原子所占比例与金对氧还原反应的本征活性密切相关,表明高能表面原子决定着金催化剂对氧还原反应的本征活性.此外,还将金纳米颗粒对氧还原反应的本征催化活性与其表面电子结构进行了关联.
Oxygen reduction reaction (ORR) in alkaline electrolyte (0.5 mol/L KOH) was studied on a series of carbon supported Au nanoparticles (NPs) with average sizes ranging from 3 to 14 nm, using the rotating disk electrode methods. Downsizing the Au NPs from 14 to 3 nm resulted in continued enhancement in both the intrinsic and mass-specific activity of Au for ORR but produced no influ-ence on the reaction mechanism or number of transferred electrons per O2 -reduction. Careful anal-yses of the particle shapes of Au NPs with varied sizes by using high-resolution transmission elec-tron microscopy enabled us to estimate the fraction of surface Au atoms at different positions or coordination (energy) state. Correlating the fraction of high energy surface atoms with the Au activ-ity for ORR disclosed the importance of high energy surface atoms in enhancing the intrinsic activity of Au. Fundamental correlation between the Au intrinsic activity for ORR and the experimentally determined surface electronic structure of Au NPs was also established.
出处
《催化学报》
CSCD
北大核心
2013年第5期942-948,共7页
基金
supported by the National Natural Science Foundation of China(21033004)
the National Basic Research Program of China(2013CB933103)~~
关键词
金纳米颗粒
尺寸效应
氧还原反应
表面电子结构
碱性电解质
Au nanoparticle
Size effect
Oxygen reduction reaction
Surface electronic structure
Alkaline electrolyte