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- Nie, Zhicheng, et al.
(författare)
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Reversed charge transfer induced by nickel in Fe-Ni/Mo2C@nitrogen-doped carbon nanobox for promoted reversible oxygen electrocatalysis
- 2024
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Ingår i: Journal of Energy Chemistry. - : Elsevier. - 2095-4956 .- 2096-885X. ; 88, s. 202-212
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between metal and support is critical in oxygen catalysis as it governs the charge transfer between these two entities, influences the electronic structures of the supported metal, affects the adsorption energies of reaction intermediates, and ultimately impacts the catalytic performance. In this study, we discovered a unique charge transfer reversal phenomenon in a metal/carbon nanohybrid system. Specifically, electrons were transferred from the metal-based species to N-doped carbon, while the carbon support reciprocally donated electrons to the metal domain upon the introduction of nickel. This led to the exceptional electrocatalytic performances of the resulting Ni-Fe/Mo2C@nitrogen-doped carbon catalyst, with a half-wave potential of 0.91 V towards oxygen reduction reaction (ORR) and a low overpotential of 290 mV at 10 mA cm−2 towards oxygen evolution reaction (OER) under alkaline conditions. Additionally, the Fe-Ni/Mo2C@carbon heterojunction catalyst demonstrated high specific capacity (794 mA h gZn−1) and excellent cycling stability (200 h) in a Zn-air battery. Theoretical calculations revealed that Mo2C effectively inhibited charge transfer from Fe to the support, while secondary doping of Ni induced a charge transfer reversal, resulting in electron accumulation in the Fe-Ni alloy region. This local electronic structure modulation significantly reduced energy barriers in the oxygen catalysis process, enhancing the catalytic efficiency of both ORR and OER. Consequently, our findings underscore the potential of manipulating charge transfer reversal between the metal and support as a promising strategy for developing highly-active and durable bi-functional oxygen electrodes.
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| 2. |
- Sun, Pengliang, et al.
(författare)
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Treasure-bowl style bifunctional site in cerium-tungsten hetero-clusters for superior solar-driven hydrogen production
- 2024
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Ingår i: Materials Horizons. - : Royal Society of Chemistry. - 2051-6347 .- 2051-6355.
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical water splitting powered by renewable energy sources hold potential for clean hydrogen production. However, there is still persistent challenges such as low solar-to-hydrogen conversion efficiency and sluggish oxygen evolution reactions. Here, we address the poor kinetics by studying and strengthening the coupling between Ce and W, and concurrently establishing Ce-W bi-atomic clusters on P,N-doped carbon (WN/WC-CeO2−x@PNC) with a “treasure-bowl” style. The bifunctional active sites are established using a novel and effective self-sacrificial strategy involving in situ induced defect formation. In addition, by altering the coupling of the W(d)-N(p) and W(d)-Ce(f) orbitals in the WN/WC-CeO2−x supramolecular clusters, we are able to disrupt the linear relationship between the binding energies of reaction intermediates, a key to obtain high catalytic performance for transition metals. Through the confinement of the WN/WC-CeO2−x composite hetero-clusters within the sub-nanometre spaces of hollow nano-bowl-shaped carbon reactors, a stable and efficient hydrogen production via water electrolysis could be achieved. When assembled together with a solar GaAs triple junction solar cell, a solar-to-hydrogen conversion efficiency of 18.92% in alkaline media could be realized. We show that the key to establish noble metal free catalysts with high efficiency lies in the fine-tuning of the metal-metal interface, forming regions with near optimal adsorption energies for the reaction intermediates participating in water electrolysis.
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