As a fuel, hydrogen has a critical role to play in driving the paradigm shift towards a green and sustainable economy. In addition to having about 3-fold higher calorific value compared to non-renewable energy sources such as coal and gasoline, the combustion of hydrogen to release energy produces water and is thus completely non-polluting. Due to the extremely low abundance of molecular hydrogen in the earth’s atmosphere (350 ppbv), electric-field driven breakdown of water is an attractive route for production of hydrogen. However, such electrolysis requires high energy input and is associated with slow rate of hydrogen production. The use of expensive platinum- and iridium-based catalysts also discourages it for wide-spread commercialization. Therefore, the transition to ‘green-hydrogen-economy’ demands approaches that lower the energy cost and material cost and simultaneously improve the hydrogen production rate.
The research work
A team of researchers from IIT Bombay led by Prof. C. Subramaniam have come up with an innovative route that provides viable solutions to all these challenges. It involves electrolysis of water in the presence of an external magnetic field. In this method, the same system that produces 1 ml of hydrogen gas required 19% lower energy to produce 3 ml of hydrogen in the same time. This is achieved by synergistically coupling the electric and magnetic fields at the
The simple approach also provides the capability to retrofit any existing electrolyser (that uses electricity to break water into hydrogen and oxygen) with external magnets without drastic change in the design, leading to increased energy efficiency of H2 production.
The electrocatalytic material — cobalt-oxide nanocubes that are dispersed over hard-carbon based nanostructured carbon florets, is of prime importance to achieve this effect and was developed with the support of the Department of Science & Technology’s Material for Energy Storage program at Technology Mission Division. It was put to use for magneto-electrocatalysis through the DST-SERB grant.
The interface between the carbon and cobalt oxide is key to magneto-electrocatalysis. It is advantageous as it forms a system that does not require the constant presence of the external magnetic field and is able to sustain the magnetisation for prolonged time periods; the magnitude of the enhancements achieved (650% increase in current density, 19% lowering of energy required and a 3-fold increase in volumetric hydrogen production rate) is unparalleled, the intermittent magnetic field required is similar to what a fridge magnet can provide. This route can be directly adopted in existing electrolyzers without any change in design or mode of operation and one-time exposure of magnetic field for 10 minutes is enough to achieve the high rate of hydrogen production for over 45 minutes.
Detailing on the experiment, Prof. Subramaniam said, “The intermittent use of an external magnetic field provides a new direction for achieving energy-efficient hydrogen generation. Other catalysts can also be explored for this purpose.”
Jayeeta Saha and Ranadeb Ball, the students who were supported by the DST funding, informed, “A basic electrolyser cell of 0.5 nm3/h capacity can be immediately upgraded to a 1.5 nm3/h capacity by replacing the catalysts and supplying the magnetic field.”