MoS2-Carbon Inter-overlapped Structures as Effective Electrocatalysts for the Hydrogen Evolution Reaction

Abstract

The ability to generate hydrogen in an economic and sustainable manner is critical to the realization of a future hydrogen economy. Electrocatalytic water splitting into molecular hydrogen using the hydrogen evolution reaction (HER) provides a viable option for hydrogen generation. Consequently, advanced non-precious metal based electrocatalysts that promote HER and reduce the overpotential are being widely researched. Here, we report on the development of MoS2-carbon inter-overlapped structures and their applicability for enhancing electrocatalytic HER. These structures were synthesized by a facile hot-injection method using ammonium tetrathiomolybdate ((NH4)2MoS4) as the precursor and oleylamine (OLA) as the solvent, followed by a carbonization step. During the synthesis protocol, OLA not only plays the role of a reacting solvent but also acts as an intercalating agent which enlarges the interlayer spacing of MoS2 to form OLA-protected monolayer MoS2. After the carbonization step, the crystallinity improves substantially, and OLA can be completely converted into carbon, thus forming an inter-overlapped superstructure, as characterized in detail using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). A Tafel slope of 118 mV/dec is obtained for the monolayer MoS2-carbon superstructure, which shows a significant improvement, as compared to the 202 mV/dec observed for OLA-protected monolayer MoS2. The enhanced HER performance is attributed to the improved conductivity along the c-axis due to the presence of carbon and the abundance of active sites due to the interlayer expansion of the monolayer MoS2 by OLA.

In Situ Electrophoretic Decorated Cactus-Type Metallic-Phase MoS2 on CaMn2O4 Nanofibers for Binder-Free Next-Generation LIBs

“…The peak detected at the binding energy of 225.94 eV corresponds to the S 2s state of MoS 2 . 24 Moreover, the XPS spectra of S 2p, as shown in Figure 2l, reveal two peaks observed at 161.58 and 162.76 eV, which can be ascribed to the S 2p 3/2 and S 2p 1/2 orbitals, respectively. 24 These XPS information validates all anticipated elements within the CMO nanofibers and MoS 2 nanoflowers.…”

Processing of Composite Electrodes of Carbon Nanotube Fabrics and Inorganic Matrices via Rapid Joule Heating

“…Nonetheless, since the D/G peak intensity ratio is less than 1, there are relatively few defects and sp 2 hybridization is still dominant, which suggests that the electrical and mechanical properties of the CNTs are largely preserved (see Tables 1 and 2). 31,34 The crystalline phase transition of the inorganic phase was examined using Raman spectroscopy and XRD. For the justdeposited CNTF/MoS 2 composite, we see amorphous peaks for MoS 2 in addition to CNT signals (Figure 3b).…”

“…Both the higher D/G peak intensity ratio and the G peak shoulder (D′ peak) are associated with defects such as functional groups. Nonetheless, since the D/G peak intensity ratio is less than 1, there are relatively few defects and sp 2 hybridization is still dominant, which suggests that the electrical and mechanical properties of the CNTs are largely preserved (see Tables and ). , …”

Molybdenum Disulfide-Based Nanomaterials for Visible-Light-Induced Photocatalysis

“…Among the chalcogenides, molybdenum disulfide (MoS 2 ) has captivated researchers with its exceptional features such as strong oxidizing activity, high stability and hardness, nontoxicity, large surface area, and a high proportion of catalytically active sites. Some major uses of MoS 2 include the photocatalytic evolution of hydrogen, , oxidative desulfurization, and the photocatalytic degradation of organic pollutants. , With its hexagonal arrangement of Mo and S atoms, one- or few-layered MoS 2 has been considered analogous to graphene; however, MoS 2 possesses a narrower band gap than graphene, which enables the generation of electron/hole pairs (e – /h + ) upon visible-light excitation and makes MoS 2 a strong candidate for visible-light-induced photocatalysis. MoS 2 has attracted considerable attention for photocatalysis because of its excellent ability to absorb light and high chemical stability.…”