In a major development that could lead to large-scale production of future fuel, a team of Indian scientists has developed a large-scale reactor that produces a substantial amount of hydrogen using sustainable sources like sunlight and water.

This is for the first time that hydrogen has been produced in a cost-effective process at a large scale. Though scientists all over the world are working towards renewable energy solutions to produce hydrogen, the achievement by scientists from the Institute of Nano Science and Technology (INST) would pave a way to produce hydrogen in a long term sustainable process, said a senior officer of the Department of Science and Technology.

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India has already set a target of 450 GW of renewable energy by 2030. One of the most economical ways to achieve this is to produce hydrogen at 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 which will benefit society in the longer term. Thus significant efforts from scientists towards achieving this goal are utmost necessary and urgent need-of-the-hour,” said Dr. Kamalakannan Kailasam the team leader of INST scientists who developed this photocatalytic converter.

His team has developed a prototype reactor that operates under natural sunlight to produce hydrogen at a larger scale (around 6.1 L in 8 hours). They have used an earth-abundant chemical called carbon nitrides as a catalyst for the purpose.

“The process had been attempted many times by many researchers using complex metal oxide/nitride/sulphide based heterogeneous systems but was very difficult to reproduce in large quantities. The INST team employed the low-cost organic semiconductor in carbon nitrides which can be prepared using cheaper precursors like urea and melamine at ease in a kilogram scale,” said a senior officer of the Department of Science and Technology.

When the sunlight falls on this semiconductor, electrons, and holes are generated. The electrons reduced the protons to produce hydrogen, and holes are consumed by some chemical agents called sacrificial agents. If the holes are not consumed, then they will recombine with the electrons. This work is supported by the DST Nano Mission NATDP project, and the related article has been published in the ‘Journal of Cleaner Production’ recently, and the team is in the process of obtaining a patent for the technology.

The INST team has been working in this area of photocatalytic water splitting to generate hydrogen for quite some time now. “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 nitrides triggered us to work on these cost-effective organic semiconductor materials for sustainable hydrogen production,” said 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 reactor is about 1 metre square, and the photocatalyst was coated in the form of panels where water flow is maintained. Upon natural sunlight irradiation, hydrogen production occurs and is quantified through gas chromatography. The team is in the process of optimising 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 forms like electricity generation through fuel cells in remote tribal areas, hydrogen stoves, and powering small gadgets, to mention a few. Eventually, they can power the transformers and e-vehicles, which are long-term research goals under progress.