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MoS₂ Nanosheets Supported on Hollow Carbon Spheres as Efficient Catalysts for Electrochemical Hydrogen Evolution Reaction.

ABSTRACT: Hybridizing structured carbon materials with MoS₂ has been demonstrated to be an effective method to increase the electrochemical hydrogen evolution reaction (HER) activity and durability of MoS₂. In this study, we report the growth of MoS₂ nanosheets on the surface of uniform hollow carbon spheres (HCS) to form a hydrangea-like nanocomposite. The HCS were formed through carbonization of a phenol formaldehyde template, and the MoS₂ nanosheets were grown on the HCS surfaces through a hydrothermal method. The nanocomposites have the advantages of significantly improved electrical conductivity, ease of varying the MoS₂ loading, and minimizing stacking of MoS₂ nanosheets, which are manifested by their remarkably improved HER performance. The well-tuned carbon-MoS₂ composite shows a Tafel slope of 48.9 mV dec^-1, an onset potential of -0.079 V (vs reversible hydrogen electrode), and an overpotential of 126 mV at the current density of 10 mA cm^-2 after 1000 potential cycles.

SUBMITTER: Li W

PROVIDER: S-EPMC6641967 | 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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MoS₂ Nanosheets Supported on Hollow Carbon Spheres as Efficient Catalysts for Electrochemical Hydrogen Evolution Reaction.

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MoS2 Nanosheets Supported on Hollow Carbon Spheres as Efficient Catalysts for Electrochemical Hydrogen Evolution Reaction.

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OmicsDI is part of the ELIXIR infrastructure

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MoS₂ Nanosheets Supported on Hollow Carbon Spheres as Efficient Catalysts for Electrochemical Hydrogen Evolution Reaction.