Morphology-Controllable Synthesis of Cobalt Telluride Branched Nanostructures on Carbon Fiber Paper as Electrocatalysts for Hydrogen Evolution Reaction

Abstract

Cobalt telluride branched nanostructures on carbon fiber paper (CFP) with two different morphologies were synthesized via solution-based conversion reaction. Both the CoTe2 with nanodendrite and CoTe with nanosheet morphologies on the CoTe2 nanotube (CoTe2 NDs/CoTe2 NTs and CoTe NSs/CoTe2 NTs) supported by CFP exhibit high activities toward hydrogen evolution reaction (HER). Particularly, the CoTe NSs/CoTe2 NTs only require an overpotential of 230.0 mV to deliver the current density of 100 mA cm(-2) in acid solution. After cycling for 5000 cycles or 20 h continual electrolysis, only a small performance loss is observed.

Novel magnetic properties of CoTe nanorods and diversified CoTe2 nanostructures obtained at different NaOH concentrations

“…Figure 6(a) shows the high-resolution spectra of Co 2p region for CoTe 2 nanostructures with different NaOH concentrations. The main peaks of Co 2p 3/2 and Co 2p 1/2 are located at about 781 eV and 796 eV, respectively, as expected for the cobalt telluride nanostructures [3,19]. Figure 6(b) shows the high-resolution spectra of the Te 3d region.…”

“…Transition metal tellurides have been actively studied recently due to their unique properties with potential applications in optoelectronics [1,2], catalysis [3,4], electrode [5,6] and magnetism [7,8]. Tellurides with different morphologies and compositions presented different properties.…”

Unconventionally Layered CoTe2 and NiTe2 as Electrocatalysts for Hydrogen Evolution

“…The peaks located at7 77.3 and 779.8 eV correspond to the Co 2p 3/2 binding energy,w hereas 792.2 and 795.5 eV correspond to the Co 2p 1/2 binding energy.T he deconvolution of Co 2p signals ( Figure 3a)r eveals that the surface of CoTe 2 comprises Co 0 and CoO species in addition to the CoTe 2 phase. [13] Using Co 2p 3/2 binding energies as reference, the signals of our CoTe 2 sample align with the literature valuesf or CoTea nd CoTe 2 which have been reportedt ob e within ar ange of 778.5 and 781.2 eV encompassing nanostructures, films, or hybrids. [12] The Co 2p 3/2 signal at 779.8 eV is deconvoluted into CoTe 2 at 779.6 eV and CoO at 780.7 eV.P arallel to this, the Co 2p 1/2 signal at 795.5 eV also has contribution from the CoTe 2 and CoO species.…”

“…The presenceo fe lementalC oo nt he surface is confirmed by the Co 2p 3/2 and 2p 1/2 binding energies at 777.3 and 792.2 eV respectively. [13,14] The proximity in signals may be attributed to the valence state of Co. Akin to CoTewith an oxidation state of Co 2 + , [14b, c] ad ivalent oxidation state of Co has been suggested for CoTe 2 in as eparate study on aC oTe 2 / carbon nanotube hybrid. Formation of surfaceo xides like CoO is ar esult of the susceptibility of CoTe 2 towardso xidation.…”

“…This deduction achievesa consensus with earlier works documenting the weakp aramagnetic nature of NiTe 2 . [13,15,21] Given that the oxidation state of the transition metal Co and Ni is + 2, the Te speciesi nC oTe 2 and NiTe 2 is formulated to be Te 2 2À .B ensch et al had also arriveda tasimilarc onclusion. [5,15] XPS deconvolution of Te 3d spectra for CoTe 2 and NiTe 2 (Figure 3b and c) shows strong resemblance to each other.B oth reveal ap air of doublets that is characteristic of MTe 2 (M = Co, Ni)a nd Te O 2 species.…”