Two-Dimensional Metallic NiTe<sub>2</sub> with Ultrahigh Environmental Stability, Conductivity, and Electrocatalytic Activity
Jianping Shi, Yahuan Huan, Mengmeng Xiao, Min Hong, Xiaoxu Zhao, Yinlu Gao, Fangfang Cui, Pengfei Yang, Stephen J. Pennycook, Jijun Zhao, Yanfeng Zhang
Abstract
Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs) supply a versatile platform for investigating newfangled physical issues and developing potential applications in electronics/spintronics/electrocatalysis. Among these, NiTe2 (a type-II Dirac semimetal) possesses a Dirac point near its Fermi level. However, as-prepared 2D MTMDCs are mostly environmentally unstable, and little attention has been paid to synthesizing such materials. Herein, a general chemical vapor deposition (CVD) approach has been designed to prepare thickness-tunable and large-domain (∼1.5 mm) 1T-NiTe2 on an atomically flat mica substrate. Significantly, ultrahigh conductivity (∼1.15 × 106 S m–1) of CVD-synthesized 1T-NiTe2 and high catalytic activity in pH-universal hydrogen evolution reaction have been uncovered. More interestingly, the 2D 1T-NiTe2 maintains robust environmental stability for more than one year and even after a variety of harsh treatments. These results hereby fill an existing research gap in synthesizing environmentally stable 2D MTMDCs, making fundamental progress in developing 2D MTMDC-based devices/catalysts.