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

TL;DR

This study investigates how the topological surface states and mirror symmetry in SnTe influence its effectiveness as an electrocatalyst for hydrogen evolution, highlighting the importance of surface orientation and defects.

Contribution

It reveals that topological surface states and mirror symmetry enhance HER activity in SnTe, with specific surface orientations and defects playing crucial roles.

Findings

SnTe (001) and (111) surfaces show higher HER activity than (211).

Surface defects like Sn vacancies or oxidation improve catalytic performance.

Topological surface states facilitate charge transfer, boosting HER efficiency.

Abstract

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.