Transition Metal-Based Catalysts for Electrochemical Water Splitting

Chen, Zhijie

Transition Metal-Based Catalysts for Electrochemical Water Splitting

Chen, Zhijie

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Publication Type:: Thesis
Issue Date:: 2022

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Field	Value	Language
dc.contributor.author	Chen, Zhijie
dc.date.accessioned	2022-09-23T03:53:03Z
dc.date.available	2022-09-23T03:53:03Z
dc.date.issued	2022
dc.identifier.uri	http://hdl.handle.net/10453/162041
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	Electrocatalytic water splitting (EWS) is a promising route to produce green hydrogen, which is centrally hindered by the anodic oxygen evolution reaction (OER) due to its sluggish kinetics. To advance the OER process, substantial efforts have been put into exploring high-performance catalysts. Recently, transition metal-based sulfide (TMS) and boride (TMB) catalysts have attracted enormous attention, while the design of novel TMSs/TMBs with high cost-effectiveness is an ongoing challenge. Hence, in this thesis, useful catalyst design strategies are developed for the construction of cost-effective TMS/TMB electrocatalysts. The P and W dual-doping strategy was first used to design OER electrocatalysts from FeB with accelerated surface reconstruction and regulated intrinsic activity of evolved FeOOH. The obtained catalyst demonstrates an excellent OER activity (an overpotential of 209 mV to achieve 10 mA cm–2), surpassing most boride-based catalysts. Specifically, anion etching facilitates surface reconstruction and W doping enhances intrinsic catalytic activity. Moreover, the hierarchical structure and amorphous features also benefit OER. This study provides a powerful strategy to construct efficient OER catalysts. A morphology control strategy was then performed to construct nickel sulfides for overall water splitting (OWS). By taking advantage of small size, large electrochemical surface area, and good conductivity, the nanoworm-like nickel sulfides exhibit better performance for OWS than the nanoplate-like analogues. This study provides a facile strategy to design sulfide-based electrocatalysts for diverse applications. Designing catalysts from wastes can further enhance catalysts' cost-effectiveness. Herein, a boriding method is developed to turn waste printed circuit boards into OER catalysts (FeNiCuSnBs). High metal recovery rates (> 99%) are attained, and the optimal FNCSB-4 attains 10 mA cm–2 at an overpotential of 199 mV. The in-depth study suggests that the superior OER performance arises from accelerated surface self-reconstruction by B/Sn co-etching, and the newly formed multimetal (oxy)hydroxides are OER active species. The boriding strategy was further implemented to convert spent adsorbents into heterostructural OER catalysts (NiCuFeB/SA) which outperforms many state-of-the-art catalysts. Comprehensive analyses suggest the high catalytic efficiency mainly attributed to the porous biochar confined well-dispersed metallic borides and the in situ evolved metal (oxy)hydroxides. This thesis has realized the design of cost-effective TMS and TMB-based electrocatalysts for EWS, which provides guidelines for further design of novel catalysts for advanced electrochemical applications from earth abundant resources. In addition, the boriding strategy presented here may open up a new avenue to design functional materials from wastes.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/162041/2/02whole.pdf
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/ppc
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Transition Metal-Based Catalysts for Electrochemical Water Splitting	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Electrocatalytic water splitting (EWS) is a promising route to produce green hydrogen, which is centrally hindered by the anodic oxygen evolution reaction (OER) due to its sluggish kinetics. To advance the OER process, substantial efforts have been put into exploring high-performance catalysts. Recently, transition metal-based sulfide (TMS) and boride (TMB) catalysts have attracted enormous attention, while the design of novel TMSs/TMBs with high cost-effectiveness is an ongoing challenge. Hence, in this thesis, useful catalyst design strategies are developed for the construction of cost-effective TMS/TMB electrocatalysts. The P and W dual-doping strategy was first used to design OER electrocatalysts from FeB with accelerated surface reconstruction and regulated intrinsic activity of evolved FeOOH. The obtained catalyst demonstrates an excellent OER activity (an overpotential of 209 mV to achieve 10 mA cm–2), surpassing most boride-based catalysts. Specifically, anion etching facilitates surface reconstruction and W doping enhances intrinsic catalytic activity. Moreover, the hierarchical structure and amorphous features also benefit OER. This study provides a powerful strategy to construct efficient OER catalysts. A morphology control strategy was then performed to construct nickel sulfides for overall water splitting (OWS). By taking advantage of small size, large electrochemical surface area, and good conductivity, the nanoworm-like nickel sulfides exhibit better performance for OWS than the nanoplate-like analogues. This study provides a facile strategy to design sulfide-based electrocatalysts for diverse applications. Designing catalysts from wastes can further enhance catalysts' cost-effectiveness. Herein, a boriding method is developed to turn waste printed circuit boards into OER catalysts (FeNiCuSnBs). High metal recovery rates (> 99%) are attained, and the optimal FNCSB-4 attains 10 mA cm–2 at an overpotential of 199 mV. The in-depth study suggests that the superior OER performance arises from accelerated surface self-reconstruction by B/Sn co-etching, and the newly formed multimetal (oxy)hydroxides are OER active species. The boriding strategy was further implemented to convert spent adsorbents into heterostructural OER catalysts (NiCuFeB/SA) which outperforms many state-of-the-art catalysts. Comprehensive analyses suggest the high catalytic efficiency mainly attributed to the porous biochar confined well-dispersed metallic borides and the in situ evolved metal (oxy)hydroxides. This thesis has realized the design of cost-effective TMS and TMB-based electrocatalysts for EWS, which provides guidelines for further design of novel catalysts for advanced electrochemical applications from earth abundant resources. In addition, the boriding strategy presented here may open up a new avenue to design functional materials from wastes.

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