催化作用
扫描透射电子显微镜
钯
选择性
电化学
贵金属
甲酸
电催化剂
吸附
金属
扩展X射线吸收精细结构
结晶学
无机化学
化学
透射电子显微镜
材料科学
吸收光谱法
纳米技术
物理化学
电极
有机化学
物理
量子力学
作者
Hee‐Eun Kim,In Hyuk Lee,Jinwon Cho,Sangyong Shin,Hyung Chul Ham,Jin Young Kim,Hyunjoo Lee
标识
DOI:10.1002/celc.201900772
摘要
Abstract Single atom catalysts (SACs) maximize the utilization of noble metal whereas nanoparticle catalysts have inner metal atoms unavailable. In this study, various electrocatalytic reactions were investigated for Pd and Pt SACs. The single atoms were immobilized on thin layers of graphitic carbon nitride with carbon black (for simplicity, C@C 3 N 4 ) to produce an electrochemically efficient and stable SACs. Single atomic structure was confirmed by high‐angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) and extended X‐ray absorption fine structure (EXAFS) analyses. Oxygen reduction reaction (ORR) and CO stripping experiments were conducted, and the results were compared with the corresponding nanoparticle catalysts. Lack of ensemble sites in the SACs resulted in two‐electron pathway for ORR; single atomic Pd on C@C 3 N 4 (C@C 3 N 4 −Pd 1 ) showed high activity and selectivity for H 2 O 2 formation. DFT calculations showed that C@C 3 N 4 −Pd 1 follows a downhill path for H 2 O 2 formation unlike single atomic Pt on C@C 3 N 4 (C@C 3 N 4 ‐Pt 1 ), resulting in enhanced H 2 O 2 selectivity. Weaker adsorption of oxygen intermediates on C@C 3 N 4 −Pd 1 resulted in enhanced ORR activity. The SACs showed no interaction with CO as confirmed by no CO stripping peak. This resulted in no activity for formic acid oxidation following indirect pathway or methanol oxidation, which necessitates CO ads as reaction intermediates. SACs can be efficient electrocatalysts with high activity and unique selectivity.
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