Sustainable hydrogen gas production is critical for future fuel infrastructure. Here, a series of phosphorous-doped carbon nitride materials were synthesized by thermal annealing of urea and ammonium hexafluorophosphate, and platinum was atomically dispersed within the structural scaffold by thermal refluxing with Zeise's salt forming Pt–N/P/Cl coordination interactions, as manifested in X-ray photoelectron and absorption spectroscopic measurements. The resulting materials were found to exhibit markedly enhanced electrocatalytic activity towards the hydrogen evolution reaction (HER) in acidic media, as compared to the P-free counterpart. This was accounted for by P doping that led to a significantly improved charge carrier density within C 3 N 4 , and the sample with the optimal P content showed an overpotential of only −22 mV to reach the current density of 10 mA cm −2 , lower than that of commercial Pt/C (−26 mV), and a mass activity (7.1 mA μg−1Pt at −70 mV vs. reversible hydrogen electrode) nearly triple that of the latter. Results from the present study highlight the significance of P doping in the manipulation of the electronic structures of metal/carbon nitride nanocomposites for high-performance HER electrocatalysis.
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Rapid preparation of carbon‐supported ruthenium nanoparticles by magnetic induction heating for efficient hydrogen evolution reaction in both acidic and alkaline media
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.
more » « less- Award ID(s):
- 1900235
- NSF-PAR ID:
- 10445233
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- SusMat
- Volume:
- 2
- Issue:
- 3
- ISSN:
- 2692-4552
- Page Range / eLocation ID:
- p. 335-346
- 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 Transition‐metal borides (TMBs) have recently attracted attention as excellent hydrogen evolution (HER) electrocatalysts in bulk crystalline materials. Herein, we show for the first time that VB and V3B4have high electrocatalytic HER activity. Furthermore, we show that the HER activity (in 0.5
m H2SO4) increases with increasing boron chain condensation in vanadium borides: Using a −23 mV overpotential decrement derived from −0.296 mV (for VB at −10 mA cm−2current density) and −0.273 mV (for V3B4) we accurately predict the overpotential of VB2(−0.204 mV) as well as that of unstudied V2B3(−0.250 mV) and hypothetical “V5B8” (−0.227 mV). We then derived an exponential equation that predicts the overpotentials of known and hypothetical Vx By phases containing at least a boron chain. These results provide a direct correlation between crystal structure and HER activity, thus paving the way for the design of even better electrocatalytic materials through structure–activity relationships. -
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Abstract Transition‐metal borides (TMBs) have recently attracted attention as excellent hydrogen evolution (HER) electrocatalysts in bulk crystalline materials. Herein, we show for the first time that VB and V3B4have high electrocatalytic HER activity. Furthermore, we show that the HER activity (in 0.5
m H2SO4) increases with increasing boron chain condensation in vanadium borides: Using a −23 mV overpotential decrement derived from −0.296 mV (for VB at −10 mA cm−2current density) and −0.273 mV (for V3B4) we accurately predict the overpotential of VB2(−0.204 mV) as well as that of unstudied V2B3(−0.250 mV) and hypothetical “V5B8” (−0.227 mV). We then derived an exponential equation that predicts the overpotentials of known and hypothetical Vx By phases containing at least a boron chain. These results provide a direct correlation between crystal structure and HER activity, thus paving the way for the design of even better electrocatalytic materials through structure–activity relationships.
