Role of topological surface states and mirror symmetry in topological crystalline insulator SnTe as an efficient electrocatalyst

• Published in: Nanoscale 2021-11, Vol.13 (43), p.1816-18172
• Main Authors: Qu, Qing, Liu, Bin, Liu, Hongtao, Liang, Jing, Wang, Jiannong, Pan, Ding, Sou, Iam Keong
• Format: Article
• Language: English
• Subjects: Charge transfer; Crystal structure; Crystallinity; Density functional theory; Electrocatalysts; Hydrogen evolution reactions; Mathematical analysis; Photoelectrons; Symmetry; Thin films; Tin tellurides; Topology; Voltammetry
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d1nr05089c

The surface orientation dependence on the hydrogen evolution reaction (HER) performance of topological crystalline insulator (TCI) SnTe thin films is studied. Their intrinsic activities are determined by linear sweep voltammetry and cyclic voltammetry measurements. It is found that SnTe (001) and (111) surfaces exhibit intrinsic activities significantly larger than the (211) surface. Density functional theory calculations reveal that pure (001) and (111) surfaces are not good electrocatalysts, while those with Sn vacancies or partially oxidized surfaces, with the latter as evidenced by X-ray photoelectron spectroscopy, have high activity. The calculated overall performance of the (001) and (111) surfaces with robust topological surface states (TSSs) is better than that of the lowly symmetric (211) surface with fragile or without TSSs, which is further supported by their measured weak antilocalization strength. The high HER activity of SnTe (001) and (111) is attributed to the enhanced charge transfer between H atoms and TSSs. We also address the effect of possible surface facets and the contrast of the HER activity of the available active sites among the three samples. Our study demonstrates that the TSSs and mirror symmetry of TCIs expedite their HER activity. The intrinsic activities of SnTe (001) and (111) surfaces with robust topological surface states (TSSs) are superior to that of a (211) surface with fragile or without TSSs, attributing to the enhanced charge transfer between H atoms and TSSs.