Abstract:
Fossil fuels have been the backbone of the technologies powering the Industrial
Revolution from early 18th century. Being limited in quantity, these sources of energies
need to be replaced by renewable ones. Moreover, consumption of fuels like oil, coal and
natural gas has been the main source of chemical pollutants like carbon dioxide (CO2),
which is directly associated with global warming. As of April 2017, CO2 concentration
reached 410 parts per million (ppm) as compared to 280 ppm in 1958 [1]. In less than 60
years CO2 concentration increased by 50%, mostly driven by the enormous amounts of
CO2 we are generating by burning fossil fuels. Of all the proposed alternative options to
fulfill energy demands across the globe, use of hydrogen (H2) appears to be the most
viable option. It is the only known fuel to have zero carbon dioxide (CO2) emission as
well as the highest gravimetric energy density [2]. Despite its benefits, the main challenge
keeping hydrogen dormant in practical application is the lack of sustainable production
methods. As of now, almost all of the H2 is generated by steam-reforming of fossil fuels
[3] which releases CO2 as a by-product making it non-viable. Clean and sustainable
methods of H2 synthesis are being explored extensively so as to realize the Hydrogen
Economy [4]. One of the clean methods to generate H2 is by electrolysis of water,
preferably using solar energy [3].
