Cr³⁺ Ion‐Induced Phase Stabilization of 1T−MoSe₂ with Abundant Active Sites for Efficient Hydrogen Evolution Reaction

Abstract

The electrocatalytic performance of transition metal dichalcogenides (TMDs) can be hugely impacted by their phase and electronic structure. In this regard, stabilization of the 1T (metallic) phase is a substantial challenge to attain superior electrocatalytic activity compared to its thermodynamically stable polymorph (2H phase). This report provides a simple approach to introduce the 1T phase into 2H−MoSe2 through heteroatom (Cr3+) doping using a hydrothermal method. 1T/2H−MoSe2 (x Cr) (x=1,2,3 and 5) materials have shown better electrocatalytic HER activities compared to the 2H−MoSe2, especially 2% Cr3+ doped MoSe2 (1T/2H−MoSe2 (2 Cr)) have shown the best catalytic activity. 1T/2H−MoSe2 (2 Cr) exhibits a current density of 20 mA cm−2 at an overpotential of 176 mV, low Tafel slope of 77 mV/dec, high double layer capacitance (Cdl) of 78.3 mF cm−2 and good cyclic stability. The improved electrocatalytic activity of 1T/2H−MoSe2 (2 Cr) could be attributed to the high conductance, high 1T phase content and the greater number of active sites resulting from the introduction of Cr3+ ions into MoSe2. In addition, density functional theory (DFT) studies predict that the introduction of Cr3+ ions into the MoSe2 monolayer increases the conduction electron density in the basal plane at room temperature which in turn supports the generation of additional active sites along the basal plane.

Co3O4 Nanocube-Templated CoS2 and CoS2/MoS2 Heterostructures for Multifunctional Electrocatalysis

“…Besides, the deconvoluted XPS spectrum of Mo 3d of MoS 2 shows the presence of two peaks centered at the B.E.s of 229.2 and 232.3 eV corresponding to Mo 3d 5/2 and Mo 3d 3/2 of Mo 4+ ion (Figure C). The noted binding energy values closely match the previous reports on 2H–MoS 2 . − In the case of CoS 2 –MoS 2 (25) heterostructure, significant changes have been encountered as the high-resolution XPS peaks of both molybdenum (Mo 3d) and cobalt (Co 2p) have been shifted to low and high B.Es, respectively, compared to pristine CoS 2 and MoS 2 . The B.E.…”

Formation of van der Waals Stacked p–n Homojunction Optoelectronic Device of Multilayered ReSe2 by Cr Doping

“…The occurrence of the Cr 3+ state was also frequently found in the 1T‐MoSe 2 phase with Cr doping. [ 45 ]…”

“…The occurrence of the Cr 3+ state was also frequently found in the 1T-MoSe 2 phase with Cr doping. [45] As the Cr impurity only behaves as an n-type or p-type dopant of ReSe 2 , it is necessary to check if any band-gap change occurred inside the Cr-doped ReSe 2 . Figure 2h shows the μTR spectra of multilayered ReSe 2 , ReSe 2 :Cr 1%, ReSe 2 :Cr 5%, ReSe 2 :Cr 10%, and ReSe 2 :Cr 20% at 300 and 10 K. The dashed lines are the experimental curves and solid lines are the leastsquares fits of a derivative Lorentzian line-shape function [15] that appropriate for the excitonic transitions in 2D materials.…”

Recent advances in molybdenum diselenide-based electrocatalysts: preparation and application in the hydrogen evolution reaction

“…200 In addition, the introduction of metal ion into MoSe 2 can also modulate the phase structure, such as 1T/2H-Ru-MoSe 2 , 120 1T′/2H-W x Mo 1− x Se 2 , 98 and Cr 3+ -induced phase transformation of 2H-MoSe 2 into 1T MoSe 2 . 201 Heteroatom doping can generate abundant active sites by constructing interfacial engineering or changing the phase structure to improve the HER performance.…”