Engineering the In-Plane Structure of Metallic Phase Molybdenum Disulfide via Co and O Dopants toward Efficient Alkaline Hydrogen Evolution

Abstract

Molybdenum disulfide (MoS 2 ) has attracted much attention as a promising alternative to Pt-based catalysts for highly efficient hydrogen generation. However, it suffers sluggish kinetics for driving the hydrogen evolution reaction (HER) process because of inert basal planes, especially in alkaline solution. Here, we show a combination of heteroatom doping and phase transformation strategies to engineer the inplane structure of MoS 2 , that trigger their catalytic activities. Systematic characterizations are performed with advanced aberration-corrected microscopy and X-ray techniques, indicating that an as-designed MoS 2 catalyst has a distorted zigzagchain superlattice in metallic phase, while its in-plane structure was engineered via the incorporation of cobalt and oxygen species. The optimal Co, O dual-doped metallic phase molybdenum disulfide (1T-MoS 2 ) electrocatalyst shows a significantly enhanced HER activity with a low overpotential of 113 mV at 10 mA cm −2 and corresponding small Tafel slope of 50 mV dec −1 , accompanied by the robust stability in alkaline media. The calculated turnover frequency is higher than 6.65 H 2 s −1 at an overpotential of 200 mV. More indepth insights from the first-principle calculations illustrate that the water dissociation as a rate-determining step was largely accelerated by the in-plane Co−O−Mo species and fast electron transfer of the catalyst. Benefiting from ingenious design and fine identifications, this work provides a fundamental understanding of the relationships among heteroatom doping, phase transformation, and performance for MoS 2 -based catalysts.

Ni‐ and Co‐Substituted Metallic MoS2 for the Alkaline Hydrogen Evolution Reaction

“…This indicates that there is no phase change of the MoS 2 during the electrochemical cycling of the catalyst in alkaline conditions. A recent study has shown the presence of Co and O dopants in 1T−MoS 2 to improve the catalytic activity for the HER under alkaline conditions . This prior study however, used a heterostructure of 1T−MoS 2 with single walled carbon nanotubes to help improve charge transfer kinetics.…”

A three-dimensional porous MoS2–PVP aerogel as a highly efficient and recyclable sorbent for oils and organic solvents

“…Nevertheless, it can be seen that the intensity ratio of (002)/(103) of MoS 2 -PVP aerogels (7.3) is higher than that of MoS 2 (1.6), confirming that the PVP promotes the exfoliation of the MoS 2 nanosheets. 37,43 The morphologies of these samples are shown in Fig The FTIR spectra in Fig. 2c and d further indicate the interaction between MoS 2 and PVP.…”

“…36 Its unique structure advantages gives it great prospects in the fields of catalysis, batteries, and sensors. [37][38][39][40][41][42] Due to the extensive study of three-dimensional (3D) aerogels, the demand for MoS 2 aerogels is increasing to realize its potential application.…”

Defects on CoS2−x: Tuning Redox Reactions for Sustainable Degradation of Organic Pollutants

“…Figure 3 b shows the Co K edge of the X‐ray absorption near‐edge structure (XANES) spectrum. Notably, compared with that of CoS 2 ‐com, the Co K edge of CoS 2 ‐1.5 h after the reaction shifted to a lower binding energy, which indicated that the valence state of Co became lower after the reaction [15] . This was because that Co 4+ /Co 3+ played the role of oxidizing .…”

“…Notably, compared with that of CoS 2 -com, the Co K edge of CoS 2 -1.5 h after the reaction shifted to a lower binding energy, which indicated that the valence state of Co became lower after the reaction. [15] This was because that Co 4+ /Co 3+ played the role of oxidizing CO 2 À to 1 O 2 in the reaction chain, and thus was reduced to Co 2+ with lower valence, which could also explain that in the high-resolution XPS spectrum of Co 2p, the peak area of Co 3+ did not increase significantly after a large amount of surface oxide layer dissolved out. Figure 3 c shows the Fe K edge of the XANES spectrum.…”