Strategies for Sustainable Fuel Production Via Photoelectrochemical Synthesis

Developing sustainable energy is highly imperative for humankind owing to the drastic rise in world population and the proportional rise in energy demand at the expense of energy consumption. Various efforts have been made to explore, generate, store, and utilize renewable energy to replace fossil fuels. Among them, solar energy is considered an alternative to fossil fuels because it is inexhaustible, clean, cost-effective, and versatile. Interestingly, this prime source provides massive energy that is high enough (1.9 × 10 8 TWh/yr) to counterattack global energy consumption (1.3 × 10 5 TWh/yr). Photoelectrochemistry has been considered a promising route to harness this incredible energy by producing sustainable energy fuels and carriers such as hydrogen, hydrocarbon, and ammonia. PEC systems have the great advantages of simple process steps and very low environmental burdens. However, this technology must overcome many challenges regarding commercial applications, particularly in fabricating electrode materials for PEC water splitting. One of the most important challenges to overcome this problem is discovering efficient catalysts for implementing photoelectrochemical (PEC) fuel production. A critical requirement for outstanding catalysts is an ability to boost the kinetics of a chemical reaction and durability against electrochemical and photo-induced degradation. Moreover, the charge-separation and transfer mechanism are the two paramount properties to consider while designing photoelectrodes. Briefly, the semiconductor materials to be used in PEC water splitting must possess a conduction band potential more negative than the reduction edge of hydrogen and a valence band potential positive to actuate water oxidation. In practice, the photocurrent density and solar-to-hydrogen (STH) efficiency of the n-type semiconductors are far behind the theoretical values. To address this critical and long-standing technical barrier, I have focused on an intense search for efficient, durable, and inexpensive alternative catalysts with moderate band gap, efficient charge excitation-separation property, and high solar energy conversion efficiency for photoelectrochemical systems of water splitting, hydrocarbon conversion, and ammonia production. Keywords : Photoelectrochemistry, Sustainable Energy, Water Splitting, Ammonia synthesis, Urea synthesis, Hydrocarbon