Green hydrogen production pathways for sustainable future with net zero emissions

Abstract

Hydrogen energy is essential to building a sustainable society with net zero carbon emissions in the face of global climate change and the energy revolution. Hydrogen generation begins with most Power-to-X methods that shape the future energy market. Electrolysis systems that use water/steam to make hydrogen have their own benefits and downsides. Electrolysis and photocatalysis are the main water-splitting methods employed to produce hydrogen. This study outlines these technologies and their future problems and potential. The literature suggests that Alkaline Water Electrolysis (AWE) is a commercial technology that can produce hydrogen on a large scale, whereas Proton Exchange Membrane Electrolysis (PEME) and Solid Oxide Electrolysis Cells (SOEC) are very efficient. Energy-efficient and economically feasible water electrolysis face several challenges. It requires effective, long-lasting catalysts to boost Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) efficiency. This publication includes a table of electrocatalyst groups. Transition metal catalysts are cheaper and as efficient as noble metal catalysts such as IrO2, RuO2, Pt, and Pd. It also highlights the challenges of electrocatalyst industrialization and commercialization and suggests solutions. The latter half of the paper reviews photocatalysis as an efficient method to produce hydrogen. It also discusses photocatalysts developed to increase H2 production efficiency. The photocatalytic water splitting activity of pure photocatalysts is enhanced by manipulating morphology, cationic/anionic doping, heterojunction/nanocomposite constructions, and defect formation. The report also covers other alternative renewable energy sources for hydrogen generation.