Green hydrogen production via photo-reforming of bio-renewable resources

Hydrogen is regarded as the cleanest form of fuel produced from different sources including biomass. The conventional hydrogen production methods include thermo-chemical processes, water splitting and biological routes. However, these conventional processes suffer from several drawbacks, including but not limited to low selectivity, thermodynamically less favorable, and expensive pre-treatment of feedstocks. Thus, photo-reforming of bio-renewable oxygenates has emerged as a promising process for green and sustainable hydrogen production because of its ability to overcome these issues mentioned above. However, hydrogen production rate via photo-reforming of bio-renewable oxygenate depends on the catalytic material, operating conditions, reactant and sacrificial agent's structure. In particular, catalyst properties such as band gap, work function, and d-band center are crucial for determining their effectiveness. In contrast, the hydrogen release capacity of oxygenates strongly depends on factors such as α-H, oxidation potential, electrical conductivity, and other structural factors. Moreover, operating conditions such as temperature, pH, and light intensity heavily affect the rate of hydrogen production. Eventually, major challenges toward commercialization of hydrogen production from bio-renewable oxygenate via photo-reforming is its cost of production and efficiency that further research efforts in this domain can overcome. Overall, this review illustrates the effect of various heterogeneous catalyst and oxygenate properties and operating conditions on hydrogen production rate to design a highly efficient photo-reforming process for hydrogen production.