INST scientists come up with a prototype for water splitting with sunlight

Scientists at the Institute of Nano Science and Technology (INST), Mohali, an autonomous institute under the Department of Science and Technology, Government of India, have developed a prototype reactor which produces hydrogen under natural sunlight, through “photocatalytic water splitting”, according to a government press release. 

The reactor designed by Dr. Kamalakannan Kailasam and his team, including Prof. Ashok K Ganguli, Dr.Vivek Bagchi, Dr.Sanyasinaidu Boddu, Dr. Prakash P N & Dr. Menaka Jha from the Institute of Nano Science and Technology (INST), can produce 6.1 litres of hydrogen in 8 hours. The researchers 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. 

                                                Image Credit: authors of the paper 

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. 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,” added 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.