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论文类型：期刊论文

发表时间：2019-09-01

发表刊物：JOURNAL OF CATALYSIS

收录刊物：EI、SCIE

卷号：377

页面范围：524-533

ISSN号：0021-9517

关键字：Iridium catalyst; Graphene; Hydrogenation; Nitroaromatic; alpha,beta-Unsaturated aldehyde; Oxygenated surface group; Hydrogen bond

摘要：Graphene is an ideal model support to investigate the influence of carbon surface chemistry on catalytic reactions. Here a mild hydrothermal method was developed to synthesize graphene-supported iridium nanocatalysts from graphene oxide. By simply varying the hydrothermal conditions, the physicochemical properties of catalysts can be tuned, which can further affect their catalytic performances. Catalysts obtained at higher H-2 pressure during hydrothermal process performed higher catalytic activities for hydrogenation of both p-chloronitrobenzene and cinnamaldehyde, benefiting from their higher reduction degrees of iridium nanoparticles. Interestingly, catalysts obtained at lower hydrothermal temperature performed higher activities for p-chloronitrobenzene hydrogenation but lower activities for cinnamaldehyde hydrogenation, due to their distinct surface chemistry of graphene. Through systematic characterizations on 11 catalysts prepared under various conditions, we found that lower hydrothermal temperature endows graphene with larger lateral dimension and more in-plane oxygenated surface groups, which facilitates the accessibility of nitro groups to catalyst surface via H-bond interaction as confirmed by density functional theory calculations. This is not true for cinnamaldehyde, of which adsorption on graphene via pi-pi stacking interaction is favorable for its hydrogenation. (C) 2019 Elsevier Inc. All rights reserved.