Recent review and evaluation of green hydrogen production via water electrolysis for a sustainable and clean energy society

Countries worldwide are seeking to decarbonize the planet by 2050 to mitigate climate change. Green hydrogen (H2) from water electrolysis is vital to worldwide decarbonization. Consequently, electrolysis-based green H2 production for large-scale renewable energy power plants and other industrial and transportation applications has grown in popularity. The main objective of this work was to provide a recent review and evaluation of water electrolysis for green H2 production. In this review, the water electrolysis process, which involves the electrochemical water splitting and photoelectrochemical (PEC) water splitting and their techno-commercial prospects including H2 production cost, along with recent developments in electrode and photoelectrode materials, and their environmental aspects for green H2 production were summarized. The results showed that the Ni-based catalyst improved the electrocatalytic activity at a current density of 10 mA/cm2, while TiO2-based catalysts enhanced PEC water-splitting processes with superior solar to H2 (STH) efficiency (3.7–16.9%). The levelized cost of H2 (LCOH) for PEC and polymer exchange membrane (PEM) electrolysis is almost similar about 9 $/kgH2, and combining water electrolysis with wind and solar energy decreases the LCOH, which surpassed coal power generation by 40%. According to the results of a life cycle assessment (LCA), global warming potential (GWP) is the environmental effect category that causes the most concern and is the subject of the most research. The PEC-based water splitting process is the most environmentally friendly H2 production method since it emits the lowest GWP per kg of produced H2 (1.0 kg CO2/Kg H2) in comparison to wind-based PEM water electrolysis (4.0 kg CO2/Kg H2) and PV-solar-based PEM water electrolysis (1.5 kg CO2/Kg H2). Interestingly, the case studies in various countries related to the green H2 were also discussed. Finally, the future of green H2 production and the challenges it faces in achieving cost-effective commercial applications were discussed.