Selective CO 2 conversion tuned by periodicities in Au 8n+4 (TBBT) 4n+8 nanoclusters
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ol of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024, China § Dan Yang and Wei Pei contributed equally to this work. 2
© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 12 July 2020 / Revised: 15 August 2020 / Accepted: 14 September 2020
ABSTRACT The structure-dependent catalytic behavior is one of the most important issues in catalysis science. However, it has not been fully understood how different types of atom-packing structures of heterogeneous catalysts precisely impact the reaction sites and pathways. Here we investigate a periodic series of Au8n + 4(TBBT)4n + 8 nanoclusters with layer-by-layer structural pattern to catalyze CO2 hydrogenation (where n = 3–6 is the number of (001) layers; TBBT = 4-tert-butyl-benzenethiolate). An encouraging evolution of CO2 conversion can be identified: The product selectivity from methanol, formic acid to ethanol can be switched by the structure-dependent deformation from the flattened, perfect, to elongated cuboids in Au8n + 4(TBBT)4n + 8. Through a combined study of experiment and theory, we demonstrate that the variation in structural patterns of catalysts can exclusively tune their adsorption strength with reaction intermediates and further control the CO2 conversion toward the different products.
KEYWORDS Au8n + 4(TBBT)4n + 8, nanocluster, periodicity, catalysis, CO2 conversion
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Introduction
Since the total structure of Au102(p-MBA)44 (p-MBA = pmercaptobenzoic acid) nanocluster was resolved [1], thiolate ligand-protected gold nanoclusters referred to as Aun(SR)m (SR = thiolate) have been in the research spotlight [2–11]. These atomically precise gold nanoclusters constitute a new generation of gold nanocatalysts, which not only offer exciting opportunities to gain fundamental insights into the exact structure-activity relationship, but also exhibit unique catalytic abilities in tailoring the reaction pathways toward desirable products at atomic-level [12–16]. Monitoring of the nanocluster structure during a catalytic reaction is important for understanding the mechanism. However, investigation on the evolution of the catalytic property with structure for heterogeneous nanocluster catalysts is complicated, as the alteration of reactive sites is often accompanied by a tiny change on the catalyst [17, 18]. Therefore, it is highly desirable to obtain a series of well-defined catalysts with no excessive complication by different surfaces and structure types; these catalysts can simplify the study of the structure-activity relationship. Recently, a series of Aun(SR)m nanoclusters that exhibit the periodicity in structural patterns have been successfully made [19]. Thus, the periodic series of Aun(SR)m nanoclusters are expected to provide an intuitive playground to explore the evolution of catalytic property with cluster structure. Catalytic conver
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