Preparation of Non-precious Metal-based Electrocatalysts via Laser Technique

Abstract

This thesis dedicates to explore new synthesis methods based on laser technique for the preparation of non-precious metal-based electrocatalysts and evaluate relevant electrocatalysis performance. In this thesis, benefiting from the high-pressure and temperature conditions created by laser, various laser-assisted synthesis routes are proposed to prepare non-precious metal-based electrocatalysts. The main contributions include: 1) 3D binder-free electrocatalytic integrated electrodes (IEs) fabricated via the combination of phase separation and laser induction methods were demonstrated for the first time. Molecular simulations were conducted to study the temporal structural evolution of polymer during laser induction process. Electrodes containing various non-precious metal-based catalysts including Co, NiFe and NiCoFe were prepared and exhibited superior performance than commercial catalysts in ORR, OER and Zinc-air batteries. This work offers an economically feasible, and industrially viable solution to the challenge of rapid fabrication of IEs of alloy nanoparticles on graphene-based supporting materials for electrocatalysis. It also opens a new route to manufacture IEs in the future. 2) Laser-induced hydrothermal reaction (LIHR) was explored using pulsed 1070 nm fiber laser. NiMo oxide nano plates and NiFe layer double hydroxide (LDH) were successfully synthesized on nickel foam via rapid laser hydrothermal reaction for the first time. Further electrochemical tests demonstrated the promising activity and durability of NiMo-based oxides and NiFe LDH in HER and OER under industrial conditions. The carbon emission and production efficiency between LIHR and conventional furnace hydrothermal reaction were compared. 3) Transition-metal based single atom catalysts (SACs) were prepared through laser-induced thermal activation of carbonized metal organic framework adsorbed with metal ions using 355 nm microsecond laser. Impacts including metal ion concentration and laser fluence on the synthesis of SACs were investigated. TEM equipped with spherical aberration corrector was applied to demonstrate the existence and successful synthesis of atomically dispersed metal sites. Synchrotron X-ray adsorption spectra were conducted to study the coordination environment of metal atoms after laser synthesis. Further electrocatalytic tests demonstrated superior ORR performance and durability of SACs than commercial Pt/C.

Date of Award	1 Aug 2023
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Andrew Thomas (Supervisor) & Lin Li (Supervisor)