Electrochemical Hydrogen Production from Nanostructured Metal Sulphide Surfaces

Abstract

Energy is an indispensable aspect of modern life, yet a significant portion of our energy demands are met by non-renewable sources like coal and hydrocarbons, which emit harmful gases contributing to environmental pollution. This highlights the urgent need for clean, renewable energy sources with minimum carbon footprint. Among the available options, hydrogen stands out due to its high energy density (120-142 KJ g-1), approximately three times that of gasoline by weight, as well as its cleanliness, renewability, and abundant availability. When combine with other renewables such as solar power and wind power, hydrogen emerge as a promising alternative energy source capable of significantly reducing greenhouse gas emissions. Currently, the predominant method of hydrogen production is steam reforming, which yields hydrogen and water along with harmful carbon dioxide as a by-product. This method highlights the pressing need for greenhouse gas-free hydrogen production processes. Electrochemical water splitting offers a viable solution as it is cost-effective, scalable, and environmentally sustainable. While noble metal-based catalysts demonstrate excellent catalytic activity and low overpotentials for water splitting, their scarcity (less than a millionth of 1% in the Earth's crust) makes them prohibitively expensive and impractical for widespread application. Therefore, alternative catalytic materials that are abundant, affordable, and effective for electrochemical hydrogen generation are urgently needed. In recent years, metal chalcogenides have emerged as promising materials for advancing the hydrogen evolution reaction (HER), a key process in renewable energy generation. This thesis explores the role of metal chalcogenides as catalysts for the HER, highlighting their importance in the transition to sustainable energy solutions. Metal chalcogenides, including transition metal sulfides, selenides, and tellurides, possess unique catalytic properties that enhance their effectiveness in facilitating hydrogen generation from water electrolysis. Their distinct electronic structures and surface chemistries enable efficient hydrogen adsorption and desorption kinetics, improving HER activity. This abstract delves into the fundamental mechanisms that govern the HER catalysis by metal chalcogenides, emphasizing their potential for driving the shift towards cleaner energy sources. Furthermore, recent advancements in the synthesis and design of metal chalcogenide catalysts for HER applications are discussed, focusing on strategies to improve their catalytic performance and stability. Notably, there has been considerable interest in transition metal chalcogenides (TMCs) such as MoS2, WS2, CrS2, VS4, and CrS2-VS4 for hydrogen generation. These TMCs has garnered considerable attention due to its unique characteristics such as a layered structure, large surface area, active edge sites, and narrow bandgap. These attributes render it applicable across various domains including hydrogen production, supercapacitors, and optoelectronics.