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Synergistic Regulation of S-Vacancy of MoS₂-Based Materials for Highly Efficient Electrocatalytic Hydrogen Evolution.

ABSTRACT: Low or excessively high concentration of S-vacancy (C _S-vacancy) is disadvantageous for the hydrogen evolution reaction (HER) activity of MoS₂-based materials. Additionally, alkaline water electrolysis is most likely to be utilized in the industry. Consequently, it is of great importance for fine-tuning C _S-vacancy to significantly improve alkaline hydrogen evolution. Herein, we have developed a one-step Ru doping coupled to compositing with CoS₂ strategy to precisely regulate C _S-vacancy of MoS₂-based materials for highly efficient HER. In our strategy, Ru doping favors the heterogeneous nucleation and growth of CoS₂, which leads to a high crystallinity of Ru-doped CoS₂ (Ru-CoS₂) and rich heterogeneous interfaces between Ru-CoS₂ and Ru-doped MoS_2-x (Ru-MoS_2-x). This facilitates the electron transfer from Ru-CoS₂ to Ru-MoS_2-x, thereby increasing C _S-vacancy of MoS₂-based materials. Additionally, the electron injection effect increases gradually with an increase in the mass of Co precursor (m _Co), which implies more S^2- leaching from MoS₂ at higher m _Co. Subsequently, C _S-vacancy of the as-synthesized samples is precisely regulated by the synergistic engineering of Ru doping and compositing with CoS₂. At C _S-vacancy = 17.1%, a balance between the intrinsic activity and the number of exposed Mo atoms (EMAs) to boost highly active EMAs should be realized. Therefore, the typical samples demonstrate excellent alkaline HER activity, such as a low overpotential of 170 mV at 100 mA cm^-2 and a TOF of 4.29 s^-1 at -0.2 V. Our results show promise for important applications in the fields of electrocatalysis or energy conversion.

SUBMITTER: Li XY

PROVIDER: S-EPMC9214220 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The design and fabrication of inexpensive highly efficient electrocatalysts for the production of hydrogen via the hydrogen evolution reaction (HER) underpin a plethora of emerging clean energy technologies. Herein, we report the fabrication of highly efficient electrocatalysts for the HER based on magnetron-sputtered MoS2 onto a nanocarbon support, termed MoS2/C. Magnetron sputtering time is explored as a function of its physiochemical composition and HER performance; increased sputtering times give rise to materials with differing compositions, i.e., Mo4+ to Mo6+ and associated S anions (sulfide, elemental, and sulfate), and improved HER outputs. An optimized sputtering time of 45 min was used to fabricate the MoS2/C material. This gave rise to an optimal HER performance with regard to its HER onset potential, achievable current, and Tafel value, which were -0.44 (vs saturated calomel electrode (SCE)), -1.45 mV s-1, and 43 mV dec-1, respectively, which has the highest composition of Mo4+ and sulfide (MoS2). Electrochemical testing toward the HER via drop casting MoS2/C upon screen-printed electrodes (SPEs) to electrically wire the nanomaterial is found to be mass coverage dependent, where the current density increases up to a critical mass (ca. 50 μg cm-2), after which a plateau is observed. To allow for a translation of the bespoke fabricated MoS2/C from laboratory to new industrial applications, MoS2/C was incorporated into the bulk ink utilized in the fabrication of SPEs (denoted as MoS2/C-SPE), thus allowing for improved electrical wiring to the MoS2/C and resulting in the production of scalable and reproducible electrocatalytic platforms. The MoS2/C-SPEs displayed far greater HER catalysis with a 450 mV reduction in the HER onset potential and a 1.70 mA cm-2 increase in the achievable current density (recorded at -0.75 V (vs SCE)), compared to a bare/unmodified graphitic SPE. The approach of using magnetron sputtering to modify carbon with MoS2 facilitates the production of mass-producible, stable, and effective electrode materials for possible use in electrolyzers, which are cost competitive to Pt and mitigate the need to use time-consuming and low-yield exfoliation techniques typically used to fabricate pristine MoS2.

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Synergistic Regulation of S-Vacancy of MoS₂-Based Materials for Highly Efficient Electrocatalytic Hydrogen Evolution.

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Dataset Information

Synergistic Regulation of S-Vacancy of MoS2-Based Materials for Highly Efficient Electrocatalytic Hydrogen Evolution.

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OmicsDI is part of the ELIXIR infrastructure

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Synergistic Regulation of S-Vacancy of MoS₂-Based Materials for Highly Efficient Electrocatalytic Hydrogen Evolution.