| 1. |
- Kagkoura, Antonia, et al.
(författare)
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Bifunctional nanostructured palladium/MoSx electrocatalyst for cathode hydrogen evolution reaction PEM water electrolysis and oxygen reduction reaction
- 2023
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Ingår i: Advanced Sustainable Systems. - : Wiley-VCH Verlagsgesellschaft. - 2366-7486. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- The creation of effective Pd-based architectures with numerous electrocatalytic active sites and efficient charge transfer is of key importance for improving the electrocatalytic performance in water electrolyzer and fuel cell applications. On the other hand, MoS2, possessing multiple electrocatalytic active sites, can act both as support and booster to Pd-based electrocatalytic structures. Herein, MoSx@Pd hybrids were successfully synthesized by using a one-pot liquid phase solvothermal strategy with stoichiometric excess of Pd. The optimized MoSx@Pd proves to be an excellent bifunctional electrocatalyst for both hydrogen evolution reaction and oxygen reduction reaction (ORR). Optimized MoSx@Pd operates the process for hydrogen evolution at the same potential as Pt/C and achieves a low overpotential of 76 mV at −10 mA cm−2 due to improved reaction kinetics and charge transfer processes between Pd and MoS2. On top of that, MoSx@Pd exhibits excellent performance and stability as cathode electrocatalyst in a polymer electrolyte membrane water electrolyzer. Simultaneously, the bifunctional electrocatalyst shows enhanced electrocatalytic ORR activity and stability by maintaining 93% of its initial activity outperforming commercial Pt/C. Finally, rotating ring disk electrode analysis reveals that ORR proceeds through the energy efficient 4e− pathway, with water being the main product, rendering MoSx@Pd a promising component for fuel cells.
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| 2. |
- Perivoliotis, Dimitrios K., et al.
(författare)
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Cobalt porphyrin/molybdenum disulfide nanoensembles for light-assisted electrocatalytic water oxidation and selective hydrogen peroxide production
- 2023
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Ingår i: Current Opinion in Chemical Engineering. - : Institute of Physics (IOP). - 2211-3398. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- The development of photo/electroactive catalysts sustainably producing hydrogen from water splitting and selectively hydrogen peroxide is of paramount importance to alleviate climate change effects. Herein, an anionic cobalt porphyrin (CoP) derivative is electrostatically interfaced with a positively charged modified molybdenum disulfide (MoS2), forming CoP/MoS2, which is accordingly employed as nonprecious photo/electrocatalyst for water oxidation reaction (WOR) and selective H2O2 production. According to the results, CoP/MoS2 shows remarkable bifunctional photo/electrocatalytic performance for WOR and 2e− pathway O2 reduction reaction (ORR) in alkaline electrolyte. Upon visible light irradiation, electrochemical measurements on a fluorine-doped tin oxide (FTO) coated glass electrode reveal an onset potential of 0.595 mV (ORR) and 1.575 mV (WOR) vs. reversible hydrogen electrode, being improved by approximately 80 mV, in both cases, compared to the dark conditions. Notably, the use of the FTO set-up not only enabled us to evaluate the photo/electrocatalytic activity of the CoP/MoS2 nanoensemble but also mimics the practical conditions in photo/electrochemical devices. The outstanding bifunctional photo/electrocatalytic performance of CoP/MoS2 is attributed to (a) the use of CoP as versatile single-atom molecular catalyst and photosensitizer (b) the strong ion-pair interactions between cationic modified MoS2 and the anionic CoP derivative, which prevent aggregation, ensuring better accessibility of the reactants to cobalt active sites, and (c) the co-existence of 1T and 2H phase at modified MoS2, offering improved electrical conductivity and intrinsic electrocatalytic activity along with enhanced intraensemble electronic interactions upon illumination. This work is expected to inspire the design of advanced and low-cost materials for the sustainable production of renewable fuels.
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| 3. |
- Perivoliotis, Dimitrios K., et al.
(författare)
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Photo/electrocatalytic hydrogen peroxide production by manganese and iron porphyrin/molybdenum disulfide nanoensembles
- 2022
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Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 18:37
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Tidskriftsartikel (refereegranskat)abstract
- The oxygen reduction reaction (ORR) 2e− pathway provides an alternative and green route for industrial hydrogen peroxide (H2O2) production. Herein, the ORR photo/electrocatalytic activity in the alkaline electrolyte of manganese and iron porphyrin (MnP and FeP, respectively) electrostatically associated with modified 1T/2H MoS2 nanosheets is reported. The best performing catalyst, MnP/MoS2, exhibits excellent electrocatalytic performance towards selective H2O2 formation, with a low overpotential of 20 mV for the 2e− ORR pathway (Eons = 680 mV vs RHE) and an H2O2 yield up to 99%. Upon visible light irradiation, MnP/MoS2 catalyst shows significant activity enhancement along with good stability. Electrochemical impedance spectroscopy assays suggest a reduced charge transfer resistance value at the interface with the electrolyte, indicating an efficient intra-ensemble transfer process of the photo-excited electrons through the formation of a type II heterojunction or Schottky contact, and therefore justifies the boosted electrochemical activities in the presence of light. Overall, this work is expected to inspire the design of novel advanced photo/electrocatalysts, paving the way for sustainable industrial H2O2 production.
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