The electrocatalytic hydrogen evolution reaction (HER) is one of the most studied and promising processes for hydrogen fuel generation. Single-atom catalysts have been shown to exhibit ultra-high HER catalytic activity, but the harsh preparation conditions and the low single-atom loading hinder their practical applications. Furthermore, promoting hydrogen evolution reaction kinetics, especially in alkaline electrolytes, remains as an important challenge. Herein, Pt/C60catalysts with high-loading, high-dispersion single-atomic platinum anchored on C60are achieved through a room-temperature synthetic strategy. Pt/C60-2 exhibits high HER catalytic performance with a low overpotential (η10) of 25 mV at 10 mA cm−2. Density functional theory calculations reveal that the Pt-C60polymeric structures in Pt/C60-2 favors water adsorption, and the shell-like charge redistribution around the Pt-bonding region induced by the curved surfaces of two adjacent C60facilitates the desorption of hydrogen, thus favoring fast reaction kinetics for hydrogen evolution.
- Award ID(s):
- 1851674
- NSF-PAR ID:
- 10212027
- Date Published:
- Journal Name:
- Energy & Environmental Science
- Volume:
- 13
- Issue:
- 9
- ISSN:
- 1754-5692
- Page Range / eLocation ID:
- 3110 to 3118
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract -
Increasing fossil fuel demands and growing concerns of global climate change have stimulated interest in the development of electrocatalysts to produce H 2 as an alternative zero-emission fuel from the electrolysis of water via hydrogen evolution reaction (HER). Precious or non-precious catalysts are typically loaded on high surface area carbon materials, and these supports play a critical role in both thermodynamics and kinetics of the HER. In this paper, we evaluate the electrocatalytic activity of a molecular hydrogen evolving catalyst, diacetyl-bis(4-methyl)-3-thiosemicarbazone Ni( ii ) (Ni-ATSM), on three different carbon surfaces: glassy carbon, carbon paste and pencil graphite. The overpotential for each modified electrode was benchmarked at a current density of −10 mA cm −2 . Carbon paste electrodes showed highest overpotentials (495 mV) compared to the other electrode surfaces. Polished pencil and glassy carbon modified electrodes performed similarly ( η = 395 mV for GCE and η = 400 mV for pencil). Pencil electrodes etched in acetone overnight prior to Ni-ATSM deposition produced lowest overpotentials ( η = 354 mV). Etching results in an increase in electroactive surface area and substantial decrease in the charge transfer resistance of the graphitic interface from 275 Ω to 50 Ω, verified using electrochemical impedance spectroscopy (EIS). Our studies demonstrate pencil graphite may serve as versatile, disposable, cost effective, and reproducible electrode surface for the evaluation of heterogeneous HER catalysts. Moreover, pencils can be easily cut with table saw to generate new surface for easy characterization of the surface such as electrochemistry, imaging and spectroscopy.more » « less
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Abstract Nickel sulfide (Ni3S2) is a promising hydrogen evolution reaction (HER) catalyst by virtue of its metallic electrical conductivity and excellent stability in alkaline medium. However, the reported catalytic activities for Ni3S2are still relatively low. Herein, an effective strategy to boost the H adsorption capability and HER performance of Ni3S2through nitrogen (N) doping is demonstrated. N‐doped Ni3S2nanosheets achieve a fairly low overpotential of 155 mV at 10 mA cm−2and an excellent exchange current density of 0.42 mA cm−2in 1.0
m KOH electrolyte. The mass activity of 16.9 mA mg−1and turnover frequency of 2.4 s−1obtained at 155 mV are significantly higher than the values reported for other Ni3S2‐based HER catalysts, and comparable to the performance of best HER catalysts in alkaline medium. These experimental data together with theoretical analysis suggest that the outstanding catalytic activity of N‐doped Ni3S2is due to the enriched active sites with favorable H adsorption free energy. The activity in the Ni3S2is highly correlated with the coordination number of the surface S atoms and the charge depletion of neighbor Ni atoms. These new findings provide important guidance for future experimental design and synthesis of optimal HER catalysts. -
Engineering catalytic sites at the atomic level provide an opportunity to understand the catalyst’s active sites, which is vital to the development of improved catalysts. Herein, we show a reliable and tunable polyoxometalate (POM) template-based synthetic strategy to atomically engineer metal doping sites onto metallic 1T-MoS2, using Anderson-type POMs (XMo6, X = FeIII, CoIII, or NiII) as precursors. Benefiting from the synergistic effect of doping metals into 1T-MoS2 and the possible tuning effect of the Ni-O-Mo bond, the optimized Ni and O incorporated 1T-MoS2 (NiO@1T-MoS2) catalyst excels in the hydrogen evolution reaction (HER). With a positive onset potential of ~ 0 V and a low overpotential of -46 mV in 1.0 M KOH, its results are comparable to 20% Pt/C. First-principles calculations reveal co-doping Ni and O into 1T-MoS2 assists the processes of both water dissociation and hydrogen generation from their intermediate states. This research will expand on the ability to improve the activities of various catalysts by precisely engineering atomic activation sites to achieve significant electronic modulations and improve atomic utilization efficiencies.more » « less
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Abstract A crucial step toward clean hydrogen (H2) energy production through water electrolysis is to develop high‐stability catalysts, which can be reliably used at high current densities for a long time. So far, platinum group metals (PGM) and their oxides, for example, Pt and iridium oxide (IrO2) have been well‐regarded as the criterion for hydrogen and oxygen evolution reactions (HER and OER) electrocatalysts. However, the PGM catalysts usually undergo severe performance decay during the long‐term operation. Herein, the in situ growth of iron phosphosulfate (Fe2P2S6) nanocrystals (NCs) catalysts on carbon paper synthesized by combing chemical vapor deposition with solvent‐thermal treatment is reported to show competitive performance and stability as compared to the state‐of‐the‐art PGM catalysts in a real water electrolyzer. A current density of 370 mA cm−2is achieved at 1.8 V when using Fe2P2S6NCs as bifunctional catalysts in an anion exchange membrane water electrolyzer. The Fe2P2S6NCs also show much better stability than the Pt‐IrO2catalysts at 300 mA cm−2for a continuous 24 h test. The surface generated FeOOH on Fe2P2S6is the real active site for OER. These results indicate that the Fe2P2S6NCs potentially can be used to replace PGM catalysts for practical water electrolyzers.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d0ee01750g
