Room‐Temperature Metal‐Catalyzed Ultrafast Gasification of Ultrathin Boron Flakes. (22nd November 2022)

• Record Type: Journal Article
• Authors: Liu, Shizhuo; Liao, PeiChi; Wei, Wei; Han, Erxun; Wang, Yunkun; Tian, Huifeng; Li, Ruijie; Pan, Jiaqi; Zhang, Chi; Li, Hao; Li, Yifei; Yao, Zhixin; Li, Zhenjiang; Yang Zhang, Lina; Li, Zhiyun; Huang, Rong; Gao, Yunan; Guo, Junjie; Chen, Ji; Cui, Yi; Liu, Lei
• Is Part Of: Advanced functional materials. Volume 33:Number 5(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-22
• Subjects: 2D materials -- boron -- CVD growths -- gasification -- surface chemistry; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202210729
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: The trivalent outer shell of boron renders this element electron‐poor but chemically rich, exhibiting more than one dozen allotropes. Its 2D polymorph has been recently synthesized on metal substrates under ultrahigh vacuum and has attracted intense interest. However, probing its properties ex situ has been challenging due to the quality degradation—surface oxidation—that occurs upon exposure to ambient environments. Herein, this surface chemistry is investigated in regard to the air stability of ultrathin boron flakes on metals prepared by atmospheric‐pressure chemical vapor deposition. The characteristic Volmer–Weber growth is recognized by the stacking of polygon‐shaped, thin flakes as isolated islands. Significantly, the metal‐catalyzed, ultrafast gasification of boron flakes at room temperature, exemplified by the complete, spontaneous vanishment of 200 nm‐thick boron islands in 3 h is observed. A two‐step mechanism, first oxygen‐involved surface oxidation and then subsequent reactions with water forming a highly volatile boric acid layer, is unambiguously revealed by combined surface characterizations. The catalysis by metal substrates, corroborated by theoretical calculations, is attributed as the crucial cause of the unprecedented gasification. The concept of oxygen‐free growth is thereby proposed for air‐sensitive material growth by introducing in situ oxygen scavengers. These findings significantly expand the fundamental understanding of the surface chemistry of boron and pave the way for the chemical vapor deposition growth of hydrophobic materials. Abstract : Ultrathin boron flakes are grown in the Volmer–Weber mode by atmospheric‐pressure chemical vapor deposition. The metal‐catalyzed, ultrafast gasification of boron flakes at room temperature, exemplified by the complete, spontaneous vanishment of 200 nm thick islands in 3 h is revealed. The two‐step mechanism related to boron surface chemistry is then confirmed. Furthermore, oxygen‐free chemical vapor depositiongrowth for air‐sensitive materials is proposed.