Ni- and sn-based colloidal nanoparticles for electrochemical energy technologies

• Autores: Junshan Lin
• Directores de la Tesis: Andreu Cabot Codina (dir. tes.), Alejandro Pérez Rodríguez (tut. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2019
• Idioma: español
• Tribunal Calificador de la Tesis: María Ibáñez Sabaté (presid.), Jordi Jacas Biendicho (secret.), Joan Rosell Llompart (voc.)
• Programa de doctorado: Programa de Doctorado en Nanociencias por la Universidad de Barcelona
• Materias:
  • Física
    • Física atómica y nuclear
      • Conversión de energía
    • Química física
      • Química de coloides
      • Electroquímica
      • Química de interfases
    • Unidades y constantes
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• Resumen

  • The thesis is mainly focused on the development of high electrochemical performance alloy NPs in the field of energy conversion (Methanol Oxidation Reaction) and storage (batteries), by means of the bottom-up assembly of nanocrystals (NCs) with finely tuned properties obtained by cost-effective and scalable colloidal synthesis routes.

    We used colloidal synthesis methods to produce Ni polyhedral and spherical NCs with narrow size. After ligand exchange, Electrodes based on Ni polyhedral NCs displayed a notably higher stability in MOR conditions than Ni spherical NCs in alkaline media. However, the stability of Ni NCs during MOR was still not fully satisfactory.

    To improve the stability, a new colloidal synthesis route of NiSn bimetallic NPs with 3-5 nm in size was developed. I further demonstrated these NPs to show high electrocatalytic activities towards methanol electroxidation in alkaline media and at the same time significantly improved stabilities when compared with nickel.

    And also, ternary Ni3 xCoxSn2 NPs with tuned composition in all the Ni/Co ratio range (0 ≤ x ≤ 3) were produced. The electrodes based on these ternary NPs provided improved catalytic performance toward MOR in alkaline medium when compared with binary Ni3Sn2 NPs. The excellent performance obtained with the substitution of small amounts of Ni by Co was concomitant to an increase of the surface coverage of active species and an enhancement of the diffusivity of the reaction limiting species. Additionally, the electrode stability was improved with respect to elemental Ni NP-based electrodes.

    Lastly, we present the results of the Sn-based alloy NCs as anode materials in LIBs and SIBs. Bimetallic CoxSn and NixSn NCs with tuned compositions were synthesized. After removing surface ligands, we demonstrated that anodes based on these NPs were characterized by relatively high energy storage capacities, with a high pseudocapacitive contribution and a notable stability.