India recently launched the world's first hydrogen production plant using nuclear energy at the Indira Gandhi Centre for Atomic Research in Kalpakkam, Tamil Nadu. Unlike other installations that rely on electricity, the new complex uses heat generated by a nuclear reactor to produce hydrogen. Hydrogen is a fuel with clean combustion, capable of replacing fossil fuels. It has a high energy density, almost three times that of gasoline, and emits only water vapor.
However, hydrogen does not occur freely in nature and must be extracted from sources such as water. Scientists worldwide are seeking efficient ways to split the water molecule and extract hydrogen.
As part of this breakthrough, researchers from the Indian Institute of Technology (IIT) Bombay have created a highly efficient and low-cost catalyst that can significantly improve green hydrogen production. The team developed a new material combining cobalt, nickel, phosphate, and graphite, which efficiently produces hydrogen and oxygen from water.
One of the simplest methods for splitting the water molecule is electrolysis, where an electric current is passed through water to separate it into hydrogen and oxygen. This process initiates two reactions: the hydrogen evolution reaction (HER) at the cathode, which generates gaseous hydrogen, and the oxygen evolution reaction (OER) at the anode, which produces gaseous oxygen. However, this process faces significant kinetic barriers requiring a large amount of energy to start. These barriers can be lowered using catalysts that accelerate the reactions without being consumed themselves.
Currently, precious metals such as platinum, ruthenium, and iridium are the gold standard for these reactions. Although they are very effective, these noble metals are scarce, extremely expensive, and prone to degradation over time under harsh operating conditions.
Dr. Savi Choudhary, an IIT Bombay researcher and the study's first author, explains: 'The main motivation was to develop an efficient and durable catalyst from common elements for general water splitting.'
To create the new catalyst, the researchers employed the molecular precursor engineering method—a technique that involves designing highly specific molecules and metal compounds that serve as building blocks or precursors for more complex materials. According to Dr. Choudhary, 'the molecular precursor approach has the advantage of allowing precise control over the composition and homogeneity of the resulting material while enabling its conversion into an active catalyst under relatively mild conditions.'
First, individual cobalt and nickel phosphate metal complexes were created. These complexes were then mixed with atomically thin layers of carbon, called exfoliated graphite, and gently heated. When the heat decomposed the carbon parts of the metal complexes, a perfectly mixed, amorphous layer of cobalt-nickel phosphate remained, uniformly distributed on conductive graphene sheets. The final result was a bifunctional catalyst that simultaneously performs both halves of the water splitting reaction.
Professor Ramasamy Murugavel, a professor at IIT Bombay and corresponding author of the study, notes: 'The combination of cobalt and nickel provides bifunctional activity for both HER and OER, while the conductive graphene substrate enhances charge transport and promotes efficient utilization of the active material.'
The amorphous nature of this material means that its atoms are arranged randomly rather than in an ordered crystal structure. This also increases its performance because its disordered structure creates a large surface area that serves as ideal sites for anchoring both HER and OER.
Dr. Choudhary comments: 'We initially expected the complexes to form crystalline phosphate materials. Instead, an amorphous phase of Co-Ni phosphate with excellent homogeneity formed. Interestingly, the combination of amorphous mixed metal phosphate and exfoliated graphite led to a significant enhancement in electrocatalytic activity.'
During testing, the new catalyst operated continuously for 72 hours with virtually no loss of performance. However, the researchers observed that the catalyst surface underwent structural transformation during the oxygen production reaction, losing some phosphate to form new oxygen-containing metal compounds. But instead of degrading the catalyst, this surface reconstruction actually helped maintain its high activity.
Professor Murugavel asserts: 'Surface reconstruction reveals an important feature of phosphate-based catalysts: under catalytic conditions, the surface reconstructs into more active oxyhydroxide species, while the underlying phosphate structure helps maintain chemical stability and structural integrity.'
The development of this robust, affordable catalyst could help ensure a sustainable energy future. By moving away from dependence on expensive precious metals and proving that low-cost, highly active materials can be designed in the lab, this research brings the world closer to producing cheap, zero-emission hydrogen fuel to power our homes, vehicles, and industries. More importantly, the team believes that the process used to manufacture the catalysts could represent a significant achievement in the production of more precise materials.
Dr. Choudhary concludes: 'We believe the most important message of this work is that molecular precursor engineering offers a powerful and versatile pathway for developing advanced electrocatalysts.'
