排序方式: 共有11条查询结果,搜索用时 15 毫秒
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Oriol Piqu Iskra Z. Koleva Francesc Vies Hristiyan A. Aleksandrov Georgi N. Vayssilov Francesc Illas 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1758-1762
Carbon moieties on late transition metals are regarded as poisoning agents in heterogeneous catalysis. Recent studies show the promoting catalytic role of subsurface C atoms in Pd surfaces and their existence in Ni and Pt surfaces. Here energetic and kinetic evidence obtained by accurate simulations on surface and nanoparticle models shows that such subsurface C species are a general issue to consider even in coinage noble‐metal systems. Subsurface C is the most stable situation in densely packed (111) surfaces of Cu and Ag, with sinking barriers low enough to be overcome at catalytic working temperatures. Low‐coordinated sites at nanoparticle edges and corners further stabilize them, even in Au, with negligible subsurface sinking barriers. The malleability of low‐coordinated sites is key in the subsurface C accommodation. The incorporation of C species decreases the electron density of the surrounding metal atoms, thus affecting their chemical and catalytic activity. 相似文献
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Lei Zhang Zichao Wei Srinivas Thanneeru Michael Meng Megan Kruzyk Gaël Ung Ben Liu Jie He 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15981-15987
The stability of metal nanocatalysts for electrocatalytic CO2 reduction is of key importance for practical application. We report the use of two polymeric N‐heterocyclic carbenes (NHC) (polydentate and monodentate) to stabilize metal nanocatalysts (Au and Pd) for efficient CO2 electroreduction. Compared with other conventional ligands including thiols and amines, metal–carbene bonds that are stable under reductive potentials prevent the nanoclustering of nanoparticles. Au nanocatalysts modified by polymeric NHC ligands show an activity retention of 86 % after CO2 reduction at ?0.9 V for 11 h, while it is less than 10 % for unmodified Au. We demonstrate that the hydrophobicity of polymer ligands and the enriched surface electron density of metal NPs through σ‐donation of NHCs substantially improve the selectivity for CO2 reduction over proton. 相似文献
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