催化作用
选择性
X射线吸收精细结构
ZSM-5型
电子顺磁共振
色散(光学)
漫反射红外傅里叶变换
氧化还原
傅里叶变换红外光谱
扫描电子显微镜
金属
热稳定性
化学
漫反射
光谱学
铜
红外光谱学
吸收(声学)
无机化学
材料科学
化学工程
分子筛
核磁共振
光催化
有机化学
工程类
物理
量子力学
光学
复合材料
作者
Lu Chen,Xuze Guan,Xinbang Wu,Hiroyuki Asakura,David G. Hopkinson,Christopher S. Allen,June Callison,Paul J. Dyson,Feng Ryan Wang
标识
DOI:10.1073/pnas.2404830121
摘要
Rigorous comparisons between single site- and nanoparticle (NP)-dispersed catalysts featuring the same composition, in terms of activity, selectivity, and reaction mechanism, are limited. This limitation is partly due to the tendency of single metal atoms to sinter into aggregated NPs at high loadings and elevated temperatures, driven by a decrease in metal surface free energy. Here, we have developed a unique two-step method for the synthesis of single Cu sites on ZSM-5 (termed Cu S /ZSM-5) with high thermal stability. The atomic-level dispersion of single Cu sites was confirmed through scanning transmission electron microscopy, X-ray absorption fine structure (XAFS), and electron paramagnetic resonance spectroscopy. The Cu S /ZSM-5 catalyst was compared to a CuO NP-based catalyst (termed Cu N /ZSM-5) in the oxidation of NH 3 to N 2 , with the former exhibiting superior activity and selectivity. Furthermore, operando XAFS and diffuse reflectance infrared Fourier transform spectroscopy studies were conducted to simultaneously assess the fate of the Cu and the surface adsorbates, providing a comprehensive understanding of the mechanism of the two catalysts. The study shows that the facile redox behavior exhibited by single Cu sites correlates with the enhanced activity observed for the Cu S /ZSM-5 catalyst.
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