合成具有富集表面結構和增強CO2還原催化活性的Pd-Cu Janus納米晶

合成具有富集表面結構和增強CO2還原催化活性的Pd-Cu Janus納米晶

作者：

小柯機器人

發布時間：2021/1/3 15:20:53

香港科技大學邵敏華團隊通過動力學控制合成具有富集表面結構和增強CO2還原催化活性的Pd−Cu Janus納米晶。 相關研究成果於2020年12月28日發表在國際頂尖學術期刊《美國化學會志》。

由於兩種不同金屬的電子耦合和幾何效應，雙金屬納米晶的催化性能往往優於單金屬納米晶。

該文報導了在十六胺和Pd二十面體種子存在下，通過葡萄糖還原Cu（II）前驅體，通過位置選擇生長，容易地合成形狀可控的Pd–Cu Janus納米晶體。具體地說，在緩慢的還原速率下，銅原子從二十面體晶種的一個頂點形核生長，形成五角雙錐或十面體形狀的五孿生Janus納米晶體。相反，在快速還原速率下，Cu原子可以直接從二十面體晶種邊緣形核或擴散到二十面體晶種邊緣，從而生成截短雙四面體形狀的單孿晶Janus納米晶。

Pd-Cu-Janus納米晶由於兩種元素的分離和表面孿晶界的存在，成為電化學還原CO2的有效催化劑。C2+產物在0.5M KHCO3溶液中的起始電位低至0.7VRHE（RHE：可逆氫電極），法拉第效率在1.0VRHE時接近51.0%。密度泛函理論和Pourbaix相圖研究表明，在電催化過程中，Pd位（金屬或氫化物形式）上的高CO覆蓋率使CO向Cu位溢出，從而促進C-C偶聯，促進C2+物種的形成。

該工作為雙金屬納米晶體的合理製備提供了新的思路，這些納米晶體具有用於催化應用所需的成分、形狀和孿晶結構。

附：英文原文

Title: Kinetically Controlled Synthesis of Pd–Cu Janus Nanocrystals with Enriched Surface Structures and Enhanced Catalytic Activities toward CO2 Reduction

Author: Zhiheng Lyu, Shangqian Zhu, Lang Xu, Zitao Chen, Yu Zhang, Minghao Xie, Tiehuai Li, Shan Zhou, Jingyue Liu, Miaofang Chi, Minhua Shao, Manos Mavrikakis, Younan Xia

Issue&Volume: December 28, 2020

Abstract: Bimetallic nanocrystals often outperform their monometallic counterparts in catalysis as a result of the electronic coupling and geometric effect arising from two different metals. Here we report a facile synthesis of Pd–Cu Janus nanocrystals with controlled shapes through site-selected growth by reducing the Cu(II) precursor with glucose in the presence of hexadecylamine and Pd icosahedral seeds. Specifically, at a slow reduction rate, the Cu atoms nucleate and grow from one vertex of the icosahedral seed to form a penta-twinned Janus nanocrystal in the shape of a pentagonal bipyramid or decahedron. At a fast reduction rate, in contrast, the Cu atoms can directly nucleate from or diffuse to the edge of the icosahedral seed for the generation of a singly twinned Janus nanocrystal in the shape of a truncated bitetrahedron. The segregation of two elements and the presence of twin boundaries on the surface make the Pd–Cu Janus nanocrystals effective catalysts for the electrochemical reduction of CO2. An onset potential as low as 0.7 VRHE (RHE: reversible hydrogen electrode) was achieved for C2+ products in 0.5 M KHCO3 solution, together with a faradaic efficiency approaching 51.0% at 1.0 VRHE. Density functional theory and Pourbaix phase diagram studies demonstrated that the high CO coverage on the Pd sites (either metallic or hydride form) during electrocatalysis enabled the spillover of CO to the Cu sites toward subsequent C–C coupling, promoting the formation of C2+ species. This work offers insights for the rational fabrication of bimetallic nanocrystals featuring desired compositions, shapes, and twin structures for catalytic applications.

DOI: 10.1021/jacs.0c05408

Source: https://pubs.acs.org/doi/10.1021/jacs.0c05408