- Title
- 2D MXenes for hydrogen evolution reaction
- Creator
- Lei, Zhihao
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2023
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- The energy crisis caused by ever-rapid depletion of limited fossil fuels and ever-serious environmental problems caused by the massive exhaust emissions have pushed the demand for developing new, sustainable, clean and eco-friendly energy to replace the traditional ones. Hydrogen, as the future energy source, stands out among a majority of candidates, due to its excellent sustainability, striking zero-emission and high energy density. Besides, generating hydrogen from water is regarded as the most eco-friendly and sustainable way, but with challenges, such as low efficiency and high cost. The core of H2 evolution is to synthesize outstanding electrocatalysts, which is able to boost the hydrogen evolution reaction (HER) kinetics. Over the past decade, 2D nanomaterials and their nanocomposites have been widely investigated as the perspective electrocatalysts and have attracted massive attentions, especially in the field of H2 production. MXenes-2D transition metal carbides or nitrides, are deemed to be the promising catalysts for HER, given that they own the variable composition and structure, fascinating properties and unexpected stability under some certain catalytic conditions. Moreover, MXenes are also excellent supports to accommodate all sorts of metal atoms (e.g., Pt, Ru, Co, Cu etc.) and metal alloys, or hybridize with other multi-dimensional nanomaterials (e.g., graphene, carbon nanotube, metal oxides/sulfides etc.), thus forming remarkable HER catalysts. Currently, there exist many different approaches to synthesize MXenes with versatile surface terminations (e.g., O, F, OH, N, S, Cl, I, Br or the mixture of them etc.). In addition, a majority of explorations on MXene focus on Ti3C2, which means that many members of MXene family may fail to be systematically studied. Therefore, there still exist considerable possibilities to achieve high performance catalysts for hydrogen production based on MXenes or their composites. In this thesis, the synthesis of a less investigated Ti3CNTx (T: -O, -OH and -F) MXene by the incorporation of Pt or Ru single atoms is introduced and illustrated. At the optimal loadings, the MXenes realize the significant enhancement of HER activities, even exceeding the benchmark of commercial Pt/C. In order to avoid the employment of noble metals to lower the cost of catalysts, non-noble metal single atoms like Zn, Co and Cu are also anchored into Ti3CNTx MXene, which similarly show an improvement of HER performance compared to the pristine MXene. However, the enhanced performance is very limited compared to Pt and Ru single atoms. This enhanced HER behaviours is attributed to the synergistic effects between MXene and metal single atoms, which not only bring abundant active sites, but also decrease the Gibbs hydrogen adsorption free energy to accelerate the HER kinetics.
- Subject
- MXene; electrocatalysts; HER; noble metals
- Identifier
- http://hdl.handle.net/1959.13/1479702
- Identifier
- uon:50351
- Rights
- Copyright 2023 Zhihao Lei
- Language
- eng
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