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In-Situ Generation of Nitrogen-Doped MoS 2 Quantum Dots Using Laser Ablation in Cryogenic Medium for Hydrogen Evolution Reaction.
- Source :
- Energies (19961073); Jan2023, Vol. 16 Issue 1, p455, 15p
- Publication Year :
- 2023
-
Abstract
- Here, nitrogen doped molybdenum disulfide quantum dots (N-MoS<subscript>2</subscript> QDs) are fabricated by making use of the pulsed laser ablation (PLA) process in liquid nitrogen (LN<subscript>2</subscript>) as a dopant agent. In fact, LN<subscript>2</subscript> contributes the rapid condensation of the plasma plume to form MoS<subscript>2</subscript> QDs, optimizing the conditions for the synthesis of N-doped MoS<subscript>2</subscript> with p-type property. The structural/optical features of the synthesized products are studied using transmission electron microscopy (TEM), absorption spectroscopy, photoluminescence (PL) spectroscopy techniques, and X-ray photoelectron spectroscopy (XPS). The TEM image shows the creation of MoS<subscript>2</subscript> QDs with 5.5 nm average size. UV-vis and PL spectroscopy confirm the formation of N-MoS<subscript>2</subscript> QDs according to the dominant peaks. The Tuck plot gives a direct band-gap of 4.34 eV for MoS<subscript>2</subscript> QDs. Furthermore, XPS spectroscopy reveals Mo-N bonding, indicating nitrogen doping as evidence of p-type MoS<subscript>2</subscript> QDs. Thus, PLA provides a single-stage way to the clean and green synthesis of the MoS<subscript>2</subscript> QDs suspension without a need for high vacuum devices and additional chemical components. Regarding the pristine MoS<subscript>2</subscript>, the N-MoS<subscript>2</subscript> QDs benefit from a low overpotential of −0.35 V at −10 mA/cm<superscript>2</superscript> per µg alongside a low Tafel slope of 300 mV/dec. Subsequently, the lower R<subscript>ct</subscript> value of N-MoS<subscript>2</subscript> QDs verifies the enhancement of the charge transfer kinetics mainly due to the elevated electronic conductivity. Furthermore, the quasi-rectangular cyclic voltammetry (CV) as well as the larger current window demonstrate a notable electrocatalytic activity. The former is based on the enhanced active sites in favor of N-MoS<subscript>2</subscript> QDs against other samples of interest. Thereby, it is discovered that the N-doped MoS<subscript>2</subscript> QD acts as an effective catalyst to notably improve the performance of the hydrogen evolution reaction (HER). [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 19961073
- Volume :
- 16
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Energies (19961073)
- Publication Type :
- Academic Journal
- Accession number :
- 161183574
- Full Text :
- https://doi.org/10.3390/en16010455