Tuning of structural and optical properties with enhanced catalytic activity in chemically synthesized Co-doped MoS₂ nanosheets

Abstract

The optimal cobalt (6% Co) doped MoS2 catalyst has shown the highest catalytic activity due to the presence of abundant defects in the active edge sites, having dominant metallic 1T phase with Co ion activated defective basal planes.

Insights into the multifunctional applications of strategically Co doped MoS2 nanoflakes

“…The XRD patterns of the undoped and various percentages of cobalt-doped MoS 2 nanostructures recorded over the 2θ range of 10 0 -70 0 had been shown in our previous research paper 40 . Here the XRD peaks of all undoped and Co-doped samples exactly match with hexagonal MoS 2 having identical peak positions.…”

“…The chemical composition and prominent presence of 1T phase along with the 2H phase in undoped 40 58 The difference between Mo 3d 3/2 and 3d 5/2 binding energy peaks corresponding to 1T phase is 3.1 eV confirming the emergence of Mo 5+ ions in 8% Co-doped MoS 2. 63 By analyzing the XPS spectra, the S: Mo peak ratio for 4% Co-doped MoS 2 is 37% smaller than 2% Co-doped MoS 2 NFs 64 .…”

“…The instrumental specifications of X-ray diffraction (XRD), Raman measurement, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) techniques to understand the existing crystalline phase and different vibrational modes present in our samples were already reported 40 . The room temperature EPR spectra of the samples were recorded using an X-band Bruker ELEXSYS 580 EPR spectrometer with 9.8492 GHz of Xband frequency.…”

“…In this work, we investigate the nature of various dominating charge transport mechanism which comes into play in the high and low-temperature region of multi-layered undoped (0% Co) and various amount of cobalt (2% Co, 4% Co, 6% Co and 8% Co) doped MoS 2 nanoflakes. Doping-induced sulfur vacancies (SVs) and cobalt dopants act as electron donors and induce localized states in the band gap leading to the narrowing of band gap 40 Layered TMDs, such as MoS 2 , have proven their efficacy in the electrochemical energy storage/conversion field, owing to their large surface area that allows the maximum exposure of surface active sites, high mechanical strength, and flexibility in the atomic scale dimension. 41 The heterogeneous electron transfer (HET) on the edge planes of MoS 2 is predicted to be higher than the basal planes, thus the edge sites are more catalytically and electrochemically active than those of their basal planes.…”

In Situ Cation Intercalation in the Interlayer of Tungsten Sulfide with Overlaying Layered Double Hydroxide in a 2D Heterostructure for Facile Electrochemical Redox Activity

“…First, doping of the Ni 2+ and Co 2+ ions at the xy plane of the nanosheet surface would have shifted the 2θ = 32.1° (006) and 57.3° (008) reflections, which, however, remain unchanged from 1T-WS 2 to WL-90 (Figure S4). Second, even if the (00 z ) planes with higher d spacing at lower 2θ attest to the interplanar spacing between stacked lamellar planes, in the case of doping, the (002) and (004) reflections would have been shifted marginally because of the small difference between the ionic radii of W 4+ (63 pm) and Ni 2+ /Co 2+ (∼70 pm). − On the contrary, ion intercalation results in large Δ2θ shifts of 1.24° and 2.4°, respectively. Lattice doping also could have resulted in Ni–S and Co–S bonds, , which are also found to be absent from the X-ray photoelectron spectroscopy (XPS) analysis of WL-90, discussed later.…”