IIT Bombay researchers develop low-cost water-splitting catalyst

Researchers at the Indian Institute of Technology (IIT) Bombay have developed a low-cost catalyst designed to improve water splitting for hydrogen production, offering an alternative to expensive precious-metal catalysts commonly used in the process.

The work comes as hydrogen continues to draw attention as a clean-burning fuel that could replace fossil fuels. The source article notes that hydrogen has a high energy density, nearly three times that of petrol, emits only water vapour, and must be extracted from sources such as water because it does not occur freely in nature.

One of the most direct ways to obtain hydrogen from water is electrolysis, which uses electrical current to separate water into hydrogen and oxygen. In that process, hydrogen is generated at the cathode through the hydrogen evolution reaction (HER), while oxygen is produced at the anode through the oxygen evolution reaction (OER). According to the researchers, both reactions face kinetic barriers that require substantial energy to initiate, making catalysts important for improving efficiency.

Current benchmark catalysts rely on noble metals such as platinum, ruthenium, and iridium, which the source article describes as highly effective but also scarce, very expensive, and vulnerable to degradation under harsh operating conditions.

"The primary motivation was to develop an efficient and durable earth-abundant catalyst for overall water splitting", explains Dr Savi Chaudhary, a researcher at IIT Bombay and the first author of the study.

A cobalt-nickel phosphate and graphite design

The IIT Bombay team developed a material made from cobalt, nickel, phosphate, and graphite that can produce both hydrogen and oxygen from water. To make it, the researchers used molecular precursor engineering, a method based on designing specific molecules and metallic compounds that serve as starting materials for more complex structures.

"the molecular precursor approach is advantageous because it allows precise control over the composition and homogeneity of the resulting material, while enabling its conversion into the active catalyst under relatively mild conditions." according to Dr Chaudhary.

The team first prepared separate metal complexes of cobalt and nickel phosphates. Those complexes were then combined with exfoliated graphite, made of atomically thin carbon layers, and gently heated. The heating process broke down the carbon portions of the metal complexes, leaving behind an evenly distributed amorphous cobalt-nickel phosphate layer across conductive graphite sheets.

That produced what the researchers described as a bifunctional catalyst, meaning it can drive both halves of the water-splitting reaction.

"The combination of cobalt and nickel provides bifunctional activity toward both HER and OER, while the conductive graphite support enhances charge transport and promotes efficient utilisation of the active material", remarks Prof. Ramaswamy Murugavel, professor at IIT Bombay and the corresponding author of the study.

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Performance and structural changes

The material’s amorphous structure - in which atoms are arranged randomly rather than in a crystal - also played a role in its performance, according to the source article, by creating a larger surface area that can act as docking sites for both HER and OER.

"We initially anticipated that the complexes would generate crystalline phosphate materials. Instead, an amorphous Co-Ni phosphate phase was formed with excellent homogeneity. Interestingly, the combination of the amorphous mixed-metal phosphate and exfoliated graphite resulted in significantly enhanced electrocatalytic activity", remarks Dr Chaudhary.

In testing, the catalyst operated continuously for 72 hours with almost no drop in performance. Researchers also found that during the oxygen-producing reaction, the catalyst surface changed structure, losing some phosphate and forming new oxygen-rich metal compounds. The source article says this surface reconstruction did not degrade the catalyst and instead helped sustain its activity.

"The surface reconstruction highlighted an important feature of phosphate-based catalysts: under catalytic conditions, the surface reconstructs into more active oxyhydroxide species while the underlying phosphate framework helps maintain chemical stability and structural integrity", says Prof Murugavel.

The researchers said the study points to a broader materials-design approach as well as a lower-cost route to water-splitting catalysis.

"We believe the most important message of this work is that molecular precursor engineering offers a powerful and versatile route for designing advanced electrocatalysts", concludes Dr Chaudhary.

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