Non-Precious Metal-Based Electrocatalysts from Prussian Blue Analogues for Energy-Related Reaction

Developing efficient electrocatalysts for oxygen evolution reaction (OER), oxygen reduction reaction (ORR), hydrogen evolution reaction (HER) and biomass oxidation is of great significance for green and renewable energy technologies, such as metal-air batteries, fuel cells, hydrogen production and biomass refining. Till now, a large amount of electrocatalysts have been already reported for active electrocatalysis, whereas, most of them suffer from either high expense or poor stability together with tedious preparation procedures. Thus, searching a facile way to attain highly effective electrocatalysts with rich abundance are extremely desirable. The key factors to improve the electrochemical performance of materials are to optimize their morphology, constructing optimum architecture, adjust effective compositions and tuning surface active sites. Prussian blue analogues (PBAs) with open frameworks have attracted growing attention as hopeful precursors to diverse transition metal-based electrocatalysts due to their easy preparation, low cost, tuneable compositions and flexibility. In this thesis, different strategies and systematic investigation have been applied to study efficient PBA-based or -derived materials for important electrochemical reactions. NiFe-based electrocatalysts have been regarded as the most promising substitute to commercial noble metals for water oxidation in alkaline conditions. To overcome their leaching problem and improve intrinsic stability without compromising activity, at first stage, the NiFe alloy covered with a discrete N-doped graphitic shell derived from PBA-NiFe for the OER was reported. It was found that the alloy core@discrete graphitic shell structure exhibits enhanced OER activity and stability, even superior to Ir/C. Detailed studies prove that the nitrogen doping, a discrete graphitic shell, and a mesoporous structure work in harmony to enhance the OER performance. Exploring efficient bifunctional electrocatalysts for ORR and OER remains significant for metal-air battery progress. At second stage of the research, a composite comprising a CoMn alloy coated with N-doped carbon and MnO was fabricated by simply annealing of a PBA-MnCo. In comparison with other controlling samples, the enhanced performance and its bifunctionality demonstrates the benefits of utilizing alloy and constructing heterojunctions for electrolysis. Following that, the next aspect in the research involved the study on designing a promising trifunctional electrocatalyst for both metal-air batteries and water splitting. The electrocatalyst derived from PBA-ZnCo precursor consisting of Co–N–C nanoparticles with Murray-type architecture and a tuneable porous hierarchy was presented. The spherical Murray-type electrocatalyst delivered great performance in ORR, OER and HER, showing that electrocatalysts with a refined porous structure and active composition beneficial for multiphase reactions by reason of efficient mass transfer and increased active sites. The last section of this thesis comes back to the PBA-CoCo itself without any further treatment for biomass oxidation which is important for economic hydrogen production due to the value-added chemicals along with hydrogen production and more favorable C–H chemistry. Herein, we reported the facilitated bio-hydrogen extraction and biomass-derived chemical formation from sugar-derived 5-hydroxymethyfurfural (HMF) through in-situ transformation of cobalt-braced electrocatalysts from PBA-CoCo. It is verified that the cyanide-braced cobalt hydroxide exhibited low-voltage for bio-hydrogen production and the cyanide ligands plays a role for the improved activity.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2019

Author dc:creator

• Deng, Chen

• OER
• Prussian blue analogues
• HER
• ORR
• Biomass reaction

Statement dc:rights

• open access
• CC BY-NC-ND 3.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by-nc-nd/3.0/au/

Language dc:language

EN

Identifier

https://doi.org/10.26190/unsworks/3849

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/64551