Tailoring Electrodes for Electrocatalytic Water Splitting

This dissertation explores techniques for developing electrocatalysts aimed at advancing renewable energy technologies, especially for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). HER and OER are the cathodic and anodic reactions of the electrochemical water-splitting process used to generate green hydrogen for energy storage and conversion technologies. The core of the research focused on developing non-noble-metal based electrocatalysts while simplifying the synthesis and fabrication processes. Background, fundamentals, and recent literature are discussed in Chapter I. In Chapter II, a wet-chemical synthesis method is employed to synthesize copper and vanadium oxide/hydroxide-based nanosheets intercalated with water molecules and carbonate ions. Nanomaterials with higher interlayer spacing provide increased surface area and a higher number of electroactive sites, enhancing OER activity. Subsequent chapters focus on the generation of binder-free electrocatalysts via electrodeposition processes which have potential for scaling to industrial applications. Two approaches are explored to enhance electrocatalytic activities: electrodeposition of porous materials onto smooth surfaces and electrodeposition of materials onto porous substrates. In Chapter III, hydrogen bubbles are utilized as template during the electrodeposition of Cu, Ni, and P onto a smooth copper sheet substrate, which is investigated for OER. A systematic study is conducted to understand the influence of electrodeposition parameters on surface area, morphology, and electrocatalytic performance. Chapter IV examines the electrodeposition of Ni, Co, Fe onto carbon-cloth substrate electrodes for OER. The elemental composition is optimized to finely tune the electrocatalytic performance. HER performance is explored for these electrodes in Chapter V, where the electrode surface is modified with sulfur using a simple and rapid ion-exchange method. Sulfurization of the electrocatalyst surface significantly enhances HER activity. In Chapter VI, selenium doping of the electrodeposited electrocatalyst is explored to tune the electroactive sites. The incorporation of Se2- ion impacts the electronic structure of electroactive sites, leading to enhancement of HER activity in various pH media. Finally, Chapter VII provides useful insights for further modifications to enhance the electrocatalytic performance. Collectively, this dissertation advances the understanding of electrocatalyst design, particularly through electrodeposition techniques, contributing to the development of efficient energy conversion and storage technologies.