Photocatalytic Hydrogen Production

A team of scientists in India has, for the first time, developed a reactor that produces a substantial amount of hydrogen using unlimited sources like sunlight and water in a cost-effective and sustainable process. Development of large-scale prototype reactors with photocatalysts and a successful use of those in large-scale hydrogen production is in the works. The use of hydrogen and helium to power our future instead of fossil fuels is proceeding nicely.

Prime Minister Narendra Modi announced the launch of a National Hydrogen Mission to accelerate plans to generate carbon-free fuel from renewables as he set a target of 2047 for the country to achieve self-reliance in energy. India has set a target of 450 GW of renewable energy by 2030. To achieve this, researchers are working towards renewable energy solutions that should be sustainable with a negligible carbon footprint.

One of the most economical ways to achieve this is to produce hydrogen on a large scale through photocatalytic water splitting. It is the long-term persistent solution for the growing renewable energy needs and a low-cost economic process that will benefit India and the world in the longer term.

Scientists from the Institute of Nano Science and Technology (INST), have developed a prototype reactor that operates under natural sunlight to produce hydrogen at a rate of around 6.1 liters in eight hours. They have used an earth-abundant chemical called carbon nitride as a catalyst for the purpose. The process was attempted many times by several researchers using complex metal oxide or nitride or sulphide-based heterogeneous systems, but it was very difficult to reproduce hydrogen in large enough quantities. The INST team employed the low-cost organic semiconductor in carbon nitride, which can be prepared using cheaper precursors like abundant urea and melamine.

When the sunlight falls on this semiconductor, electrons and holes are generated. The electrons reduce the protons to produce hydrogen and the holes are consumed by chemical agents called sacrificial agents. If the holes are not consumed, they will recombine with the electrons. The team is in the process of obtaining a patent for the technology.

"The energy crisis and ever-threatening climate crisis urged us to work on this promising way of hydrogen production through photocatalytic water splitting. The stability and chemical flexibility of having different organic groups in carbon nitride triggered us to work on these cost-effective organic semiconductor materials for sustainable hydrogen production," said INST team member Dr. Kamalakannan.

The INST team started from the lab-scale process to the bulk scale of developing the photocatalyst and hydrogen production through a large prototype reactor. The team is in the process of optimizing the hydrogen production with effective sunlight hours, in addition to the purity of the hydrogen, moisture traps and gas separation membranes so as to hyphenate with the fuel cells.

Hydrogen generated in this manner can be used in many ways such as electricity generation through fuel cells in many remote areas of India, hydrogen stoves, and for powering small gadgets, to mention a few. Eventually, they can power transformers and e-vehicles, which are long-term research goals that are under progress. With the cost efficiency of using sunlight and water to generate hydrogen fuel, the prospects are bright for this form of alternative energy production.