Tappan Bryce A, Chen Keying, Lu Haipeng, Sharada Shaama Mallikarjun, Brutchey Richard L
Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089, United States.
ACS Appl Mater Interfaces. 2020 Apr 8;12(14):16394-16401. doi: 10.1021/acsami.0c00025. Epub 2020 Mar 25.
N-heterocyclic carbenes (NHCs) are an important class of ligands capable of making strong carbon-metal bonds. Recently, there has been a growing interest in the study of carbene-ligated nanocrystals, primarily coinage metal nanocrystals, which have found application as catalysts for numerous reactions. The general ability of NHC ligands to positively affect the catalytic properties of other types of nanocrystal catalysts remains unknown. Herein, we present the first carbene-stabilized CuP nanocrystals. Inquiries into the mechanism of formation of NHC-ligated CuP nanocrystals suggest that crystalline CuP forms directly as a result of a high-temperature metathesis reaction between a tris(trimethylsilyl)phosphine precursor and an NHC-CuBr precursor, the latter of which behaves as a source of both the carbene ligand and Cu. To study the effect of the NHC surface ligands on the catalytic performance, we tested the electrocatalytic hydrogen evolving ability of the NHC-ligated CuP nanocrystals and found that they possess superior activity to analogous oleylamine-ligated CuP nanocrystals. Density functional theory calculations suggest that the NHC ligands minimize unfavorable electrostatic interactions between the copper phosphide surface and H during the first step of the hydrogen evolution reaction, which contributes to the superior performance of NHC-ligated CuP catalysts as compared to oleylamine-ligated CuP catalysts.
N-杂环卡宾（NHCs）是一类重要的配体，能够形成强的碳-金属键。最近，人们对卡宾配位的纳米晶体，主要是贵金属纳米晶体的研究兴趣日益浓厚，这些纳米晶体已被用作多种反应的催化剂。NHC配体对其他类型纳米晶体催化剂催化性能产生积极影响的一般能力仍然未知。在此，我们展示了首例卡宾稳定的CuP纳米晶体。对NHC配位的CuP纳米晶体形成机制的研究表明，结晶CuP是由三（三甲基硅基）膦前体与NHC-CuBr前体之间的高温复分解反应直接形成的，后者同时作为卡宾配体和Cu的来源。为了研究NHC表面配体对催化性能的影响，我们测试了NHC配位的CuP纳米晶体的电催化析氢能力，发现它们比类似的油胺配位的CuP纳米晶体具有更高的活性。密度泛函理论计算表明，在析氢反应的第一步，NHC配体使磷化铜表面与H之间不利的静电相互作用最小化，这有助于NHC配位的CuP催化剂比油胺配位的CuP催化剂具有更优异的性能。
