Improvements and optimisation of water electrolysis for hydrogen production

[Truncated abstract] Hydrogen as an important energy carrier has wide applications and great potentials. With ever increasing energy costs and concerns with climate change associated with carbon dioxide emissions from the use of fossil fuels, hydrogen has in recent years become very popular as it is perceived as a clean fuel that emits almost no pollutants other than water and can be produced using any primary energy sources, with renewable energy being most attractive. More importantly, hydrogen works with fuel cells and together, they may serve as one of the solutions to sustainable energy supply and use in the long run. Alkaline water electrolysis for producing hydrogen has been known for centuries and has the advantage of producing ultra-pure hydrogen which is perfect for fuel cells. However its applications are often limited to small scales and unique situations where access to large scale hydrogen production plants is not possible or uneconomical. The widespread utilisation of alkaline water electrolysis is faced with a number of technical and cost challenges due to its high energy consumption and low efficiency. The present research aims to investigate the origins of the causes for the high energy consumption of water electrolysis. Efforts are also made to understand and alleviate the high energy consumption by applying electrode modifications and managing the behaviour of electrolytic bubbles. Through reviewing the literature, a number of scientific and technical gaps between the current state of knowledge about alkaline water electrolysis and the industrial practice were identified. There has not been any effort for quantifying the energy barriers or resistances of the water electrolysis process. Many research efforts mainly focus on finding or evaluating new electrode materials, and the effect of electrode modification and electrode composition on electrode reactions has not been fully understood and studied.