Unconventionally Layered CoTe₂ and NiTe₂ as Electrocatalysts for Hydrogen Evolution

Abstract

Two members of the transition metal ditelluride family, CoTe and NiTe , exist in multiple structures encompassing marcasite-, pyrite- and CdI related structures. The allotrope modification is influenced by weak changes in stoichiometry and synthesis. It is crucial to emphasize that the CdI structure type is manifested by NiTe while the CoTe adopts a related structure for a non-stoichiometric composition with ratio below 1:1.8. The obtained structure is based on LiTiS which is derived from CdI structure, however contains a polymeric cobalt network. Despite the atypical nature of their layered structure, layered phases of CoTe and NiTe are rarely cast into the spotlight. Here, layered CoTe and NiTe are investigated for their electrochemical and electrocatalytic properties. In electrocatalytic aspects, layered CoTe and NiTe demonstrate low overpotentials and small Tafel slopes that are quintessential features of hydrogen evolution electrocatalysts. These findings impart fundamental insights to the transition metal ditelluride family and affirm the prospective use of layered CoTe and NiTe in electrochemical applications.

Nickel Ditelluride Nanosheet Arrays: A Highly Efficient Electrocatalyst for the Oxygen Evolution Reaction

“…The peaks at 855.6 and 873.5 eV with respective shakeup satellite can be designated to Ni 2+ arising from inevitable surface oxidation of NiTe 2 . In Figure c, the peaks at 583.5 and 573.2 eV are assigned to Te 3d 3/2 and Te 3d 5/2 in NiTe 2 , respectively, and two sharp peaks with binding energies at 586.5 and 576.2 eV correspond to the surface oxidation state of Te specie ,. In Figure d, the peaks at 530.3, 531.3, and 532.8 eV are associated with lattice O from metal‐oxygen bonds, adsorbed O from the surface hydroxy and/or adsorbed oxygen species, and O from H 2 O adsorbed on the surface, respectively,, indicating an obvious surface oxidation of NiTe 2 nanosheet and the formation of NiO and TeO 2 on NiTe 2 surface ,…”

“…Figure b shows two spin‐orbit doublets and two shakeup satellites (labelled as “Sat.”) of Ni element. The peaks centered at 853.3 and 870.5 eV correspond to Ni 2+ in NiTe 2 . The peaks at 855.6 and 873.5 eV with respective shakeup satellite can be designated to Ni 2+ arising from inevitable surface oxidation of NiTe 2 .…”

Few‐Layer Tellurium: Cathodic Exfoliation and Doping for Collaborative Hydrogen Evolution

“…This Volmer–Heyrovsky mechanism is consistent with previous findings for metal (di)tellurides, such as Bi 2 Te 3 , CoTe 2 , and NiTe 2 . [ 24,30 ] Further stability test (Figure 5d) proves the strong interaction between Pt sites and the Te NS substrates under reaction conditions, where a stable current density of 28.9 mA cm −2 is maintained for 2 h (η = 250 mV). Inductively coupled plasma atomic emission spectroscopy suggests an overall 0.75 at% Pt after the 2‐hour reaction, indicating a Pt loss of 4.4%.…”

“…All spectra show the presence of Te and O due to the inevitable oxidation of surface Te 0 to TeO 2 when exposed to air. [ 24 ] The surface atomic ratio between foreign metal and Te is 0.10:0.90 (Pt:Te) and 0.13:0.87 (Ni:Te) for Pt/Te and Ni/Te, respectively. Figure a compares the high‐resolution core‐level spectra of the Te 3 d region, featuring two groups: Te 3 d 5/2 and Te 3 d 3/2 .…”

Two‐Dimensional Metal Telluride Atomic Crystals: Preparation, Physical Properties, and Applications

“…Reproduced with permission. [ 318 ] Copyright 2017, Wiley‐VCH. e) Schematic of photocatalytic nitrogen reduction over Fe‐MoTe 2 nanosheets under visible light irradiation.…”