- Award ID(s):
- 1900235
- NSF-PAR ID:
- 10388370
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- Volume:
- 10
- Issue:
- 11
- ISSN:
- 2050-7488
- Page Range / eLocation ID:
- 5962 to 5970
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Hydrogen evolution reaction catalyzed by ruthenium ion-complexed graphitic carbon nitride nanosheetsThe development of cost-effective, high-performance electrocatalysts for hydrogen evolution reaction (HER) is urgently needed. In the present study, a new type of HER catalyst was developed where ruthenium ions were embedded into the molecular skeletons of graphitic carbon nitride (C 3 N 4 ) nanosheets of 2.0 ± 0.4 nm in thickness by refluxing C 3 N 4 and RuCl 3 in water. This took advantage of the strong affinity of ruthenium ions to pyridinic nitrogen of the tri- s -triazine units of C 3 N 4 . The formation of C 3 N 4 –Ru nanocomposites was confirmed by optical and X-ray photoelectron spectroscopic measurements, which suggested charge transfer from the C 3 N 4 scaffold to the ruthenium centers. Significantly, the hybrid materials were readily dispersible in water and exhibited apparent electrocatalytic activity towards HER in acid and their activity increased with the loading of ruthenium metal centers in the C 3 N 4 matrix. Within the present experimental context, the sample saturated with ruthenium ion complexation at a ruthenium to pyridinic nitrogen atomic ratio of ca. 1 : 2 displayed the best performance, with an overpotential of only 140 mV to achieve the current density of 10 mA cm −2 , a low Tafel slope of 57 mV dec −1 , and a large exchange current density of 0.072 mA cm −2 . The activity was markedly lower when C 3 N 4 was embedded with other metal ions such as Fe 3+ , Co 3+ , Ni 3+ and Cu 2+ . This suggests minimal contributions from the C 3 N 4 nanosheets to the HER activity, and the activity was most likely due to the formation of Ru–N moieties where the synergistic interactions between the carbon nitride and ruthenium metal centers facilitated the adsorption of hydrogen. This was strongly supported by results from density functional theory calculations.more » « less
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Abstract Ruthenium has been hailed as a competitive alternative for platinum toward hydrogen evolution reaction (HER), a critical process in electrochemical water splitting. In this study, we successfully prepare metallic Ru nanoparticles supported on carbon paper by utilizing a novel magnetic induction heating (MIH) method. The samples are obtained within seconds, featuring a Cl‐enriched surface that is unattainable via conventional thermal annealing. The best sample within the series shows a remarkable HER activity in both acidic and alkaline media with an overpotential of only ‐23 and ‐12 mV to reach the current density of 10 mA/cm2, highly comparable to that of the Pt/C benchmark. Theoretical studies based on density functional theory show that the excellent electrocatalytic activity is accounted by the surface metal‐Cl species that facilitate charge transfer and downshift the d‐band center. Results from this study highlight the unique advantages of MIH in rapid sample preparation, where residual anion ligands play a critical role in manipulating the electronic properties of the metal surfaces and the eventual electrocatalytic activity.
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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. -
Abstract 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.
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