Basal and edge plane activity of two-dimensional Dirac semimetal NiTe2 for hydrogen evolution reaction

Nickel ditelluride (NiTe 2 ), one of the group-10 transition metal dichalcogenides, has shown intriguing surface states originating from its topological semimetallicity. Here, we demonstrate abnormal catalytic activities at the NiTe 2 surface for the hydrogen evolution reaction (HER). We investigate the differences in catalytic activities at the basal and edge planes of NiTe 2 using a micro-sized electrochemical reactor. The basal plane is found to be more active than the edge plane, resulting in a current density at the basal plane of NiTe 2 exceeding 700 mA/cm 2 with a small overpotential of −0.162 V. Interestingly, our ab initio calculations show a discrepancy with the experimental measurements, indicating that the crystal-orientation-dependent HER activity highlights the unique characteristics of a topological semimetal, which can significantly influence the HER in NiTe 2 catalysts. • We investigated the anisotropic HER activity in the type II Dirac semimetal NiTe 2 using DFT calculations and electrochemical measurements. • DFT calculations suggest that edge plane Ni atoms are more favorable active sites for HER than basal plane atoms. • However, electrochemical measurements with the HER microreactor show that the basal plane exhibits higher catalytic activity than the edge plane. • This discrepancy is attributed to Dirac fermions near the Fermi level, which enhance carrier transport at the interface. • Our findings highlight the unique role of topological electronic states in catalysis, opening new possibilities for energy conversion applications.