Boosting Highly Active Exposed Mo Atoms by Fine-Tuning S-Vacancies of MoS₂-Based Materials for Efficient Hydrogen Evolution

Abstract

Guided by the theoretical calculation, achieving an efficient hydrogen evolution reaction (HER) by S-vacancy engineering toward MoS2-based materials is quite challenging due to the contradictory relationship between the adsorption free energy of hydrogen atoms (ΔG H) of the exposed Mo atoms (EMAs) and the number of EMAs per unit area (N EMAs). Herein, we demonstrate a novel one-pot incorporating-assisted compositing strategy to realize fine-tuning the concentration of S-vacancies (C S‑vacancies) of MoS2-based materials to boost highly active EMAs for efficient HER. In our strategy, S-vacancies are modulated into basal planes of MoS2 via decreasing the formation energy of S-vacancies by oxygen incorporation; moreover, C S‑vacancies of the basal planes is precisely regulated by simply controlling the molar amount of the Co precursor based on the electron injection effect. At low or excessively high C S‑vacancies, the as-synthesized electrocatalysts lack “highly active EMAs” in quantity or nature. The balance between the intrinsic activity of EMAs and N EMAs is realized for boosting EMAs with high catalytic performance. The optimal electrocatalysts exhibit excellent activity and stability at fine-tuning C S‑vacancies to 9.61%. Our results will pave a novel strategy for unlocking the potential of an inert basal plane in MoS2 for high-performance HER.

Engineering Rich Active Sites and Efficient Water Dissociation for Ni-Doped MoS2/CoS2 Hierarchical Structures toward Excellent Alkaline Hydrogen Evolution

“…Associated with the morphology of Ni-MoS 2 -CoS 2 -CC-0.3 (Figure d) and the above results, we further deduce that CoS 2 -CC nanoneedles are uniformly covered by Ni-doped MoS 2 nanosheets for architecting Ni-MoS 2 -CoS 2 -CC-0.3 after hydrothermal synthesis. Moreover, in our viewpoint, such architectures favor the preferentially exposed unsaturated sulfur atoms or active sites for 2H-MoS 2 Figure e–g presents high-resolution transmission electron microscopy (HRTEM) images of Ni-MoS 2 -CoS 2 -CC-0.3.…”

“…This is because the adsorption free energy of hydrogen atoms (Δ G H ) at such atoms approaches ca. −0.06 eV close to zero . Next, we characterize the S 2p high-resolution XPS spectra of all samples after electrochemical treatments (Figure d).…”

“…−0.06 eV close to zero. 50 Next, we characterize the S 2p high-resolution XPS spectra of all samples after electrochemical treatments (Figure 4d). From this figure, all S 2p XPS spectra are divided into four characteristic peaks.…”

Intensifying Hydrogen Spillover for Boosting Electrocatalytic Hydrogen Evolution Reaction

“…According to Sabatier's principle, a highly favorable HER electrocatalyst should possess the near‐zero value of Gibbs free energy [18–21] . However, as is well known to all, the ▵G H values of most of the noble‐metal‐free electrocatalysts are greater than zero, while some other Pt‐free noble metals possess the ▵G H values smaller than zero, which thus render them display poorer HER activity than Pt catalyst [22,23] . By taking these factors into considerations, many effective strategies have been successfully proposed, and some promising electrocatalysts have been developed [24–27] .…”

RuO2-NiO Nanosheets on Conductive Nickel Foam for Reliable and Regeneratable Seawater Splitting

“…Nonprecious transition-metal-based materials have been extensively explored due to the balanced HER performance and cost, such as transition metal/alloys, ,− chalcogenides, − phosphides, − and carbides. − Though some catalysts show better HER activity than the state-of-the-art Pt/C catalyst in alkaline media, the unstable structure and deteriorative HER performance are also observed during long-term stability measurements. , Moreover, strict and harsh conditions are required for the preparation of these active catalysts, e.g., toxic and corrosive PH 3 for phosphides and extremely high temperatures for carbides. , Green and scaled-up syntheses of highly efficient catalysts are in demand for industrial-scale water electrolysis.…”