Gong, Manxi;
(2025)
Design of Pt-Based Bimetallic Electrocatalysts for
the Oxygen Reduction Reaction.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The oxygen reduction reaction (ORR) at the cathode is crucial for clean energy conversion applications such as proton exchange membrane fuel cells (PEMFCs). PtM (e.g., Ni, Cu, Ru) bimetallic/alloy catalysts are considered the most attractive candidates for the ORR. The promoting effects induced by the transition metal weaken the binding energies of oxygen-containing ORR intermediates (e.g., O, OH, OOH) by altering the electronic properties, such as the d-band centre or vacancy. Here, a series of PtNi/NC, PtNi/C, PtCu/C, and PtRu/C bimetallic nanoparticles with different surface modifications were successfully synthesised. Advanced Pt-based catalyst design aims to build an understanding of the relationships between surface segregation-structure and structure-activity in Pt-based bimetallic nanoparticles, as well as to identify valid descriptors of their ORR activity. A heat-treatment annealing strategy for optimising the ORR performance of PtCu/C and PtRu/C bimetallic nanoparticle catalysts is discussed in Chapter 3. A clear volcano-shaped relationship between treatment conditions and ORR efficiency is demonstrated by varying the annealing conditions for the two catalyst systems. The studies in Chapter 4 establish a relationship among strain effects, surface segregation, and ORR MA for Pt-skin@PtNi bimetallic nanoparticles. This work demonstrates the use of direct and tunable synthetic methods to suggest structural modifications for PtNi/C bimetallic catalysts. Chapter 5 proposes an ammonia annealing surface modification process, forming a unique Pt1Ni1-x_Nix_NC structure through the detachment of surface Ni driven by hot ammonia. This process exposes more Pt on the catalyst surface and induces a surface compressive strain effect, leading to enhanced ORR activity and durability.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Design of Pt-Based Bimetallic Electrocatalysts for the Oxygen Reduction Reaction |
| Language: | English |
| Additional information: | Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10205992 |
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