The rapidly increasing demand for clean energy has stimulated extensive
research efforts on the renewable energy technologies, such as fuel cells, hydrogen
and oxygen production from water splitting, and rechargeable metal-air batteries.
The underlying chemical processes, including the oxygen evolution reaction (OER),
hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), generally
suffer from sluggish reaction kinetics. Therefore, effective catalysts are necessary to
facilitate the reactions. This thesis focuses on the development of laser-induced
graphene (LIG) derived materials and catalysts for electrochemical energy storage
devices. LIG is a 3D porous graphene material grown on a flexible substrate that is
prepared by a one-step laser scribing process on commercial polyimide (PI) film.
The LIG derived from PI is highly porous and is easily synthesized under ambient
conditions in a scalable process.
Chapter 1 discusses the oxidation of LIG by O2 plasma to form oxidized LIG,
which boosts its performance in both OER and ORR resulting in an enhanced activity
towards rechargeable Li-O2 battery. In Chapter 2, a distinctive re-lasing method was
proposed to prepare metal oxide/LIG composites as efficient catalysts for water
oxidation (OER). Unlike the conventional methods, such as solvo-/hydro-thermal, thermal pyrolysis or chemical vapor deposition processes, the re-lasing synthesizes
the NiFe-based catalysts through a facile laser scribing process without any tedious
procedures. Chapter 3 introduces a bifunctional catalyst Co3O4/LIG that was
synthesized through a facile re-lasing process, showing OER and ORR activity
comparable to noble metal-based catalysts in alkaline electrolyte. Furthermore, the
Co3O4/LIG exhibited promising performance in Zn-air and Li-O2 batteries. Chapter 4
discusses ternary metal oxide/graphene hybrid catalysts by combining ORR-active
Co/Mn with OER-active Ni and Fe species to promote the bifunctional activity all in
an in situ formed LIG flexible film. These hybrid catalysts exhibit high catalytic
activity and surpass the performance of precious metal Pt and RuO2 catalysts in Znair batteries and demonstrate applications in flexible Zn-air batteries that would be
beneficial for wearable and flexible electronic devices. Chapter 5 discusses the
performance of bifunctional OER/ORR catalysts MnNiFe/LIG (M111/LIG and
M311/LIG, where the numbers reflect the relative molar ratio of Mn, Ni and Fe
species) in Li-O2 and Li-air batteries without the presence of a redox mediator. The
underlying mechanism in Li-O2 battery was investigated. Chapter 6 introduces the
design of dual polymer gel electrolyte (DPGE). The combination of DPGE with a Mnbased catalyst enhance the performance of quasi-solid-state Li-O2 batteries.