Bismuth-based nanomaterials-assisted photocatalytic water splitting for sustainable hydrogen production

The rapidly increase in the world's population has resulted in a corresponding increase in the energy demand. This demand is largely being met by fossil fuels for power generation, industrial fuel and transportation. However, due to the limited availability of fossil fuels and their negative effects on the environment. The use of fossil fuels results in by-products such as carbon, nitrogen and sulfur oxides which have negative impacts on the environment. Therefore. There is an urgent need to develop alternative greener energy sources that are sustainable and have minimal environmental impacts. Hydrogen is one such alternative energy source of attention. Harvesting sunlight through the use of solar panels is already being employed at domestic and commercial levels. Photocatalytic water splitting, which aims to produce hydrogen by utilizing unlimited sources including water and sunlight, is another potential process for alternative energy production. The conversion of water into hydrogen and oxygen through sunlight is an innovative process that directly converts sunlight into chemical energy in the form of hydrogen and oxygen via photocatalytic water splitting. Numerous photocatalytic materials are available for photocatalytic hydrogen production, but bismuth-based materials are the most suitable as they are non-toxic, economical, opto-electronically active, have suitable band positions for photocatalysis, and exhibit excellent photo-stability. To provide summary of latest research in the field of photocatalytic water splitting, a comprehensive review is favorable to suggest future research directions aimed at discovering solutions to current challenges. This review emphasizes the need for alternative energy sources and the competitiveness of photocatalytic water splitting for hydrogen production. The mechanism and thermodynamics of the photocatalytic water splitting have been discussed, along with the properties of an ideal photocatalyst for photocatalytic hydrogen production with a special focus on the bismuth-based photocatalysts. The optimization of synthetic and photocatalytic processes is crucial for commercial use with much improved hydrogen production in terms of cost and quantity without harming environment at any stage. Furthermore, current challenges and future perspectives have been presented for upcoming research in this domain.