JNCASR Scientists Develop Metal-Free Piezocatalyst for Efficient Green H₂ Production

Recognizing its transformative potential, the Government of India launched the National Green Hydrogen Mission to scale up H₂ production, enhance research, and establish India as a global hydrogen hub.

In a groundbreaking advancement towards a sustainable energy future, researchers from India have developed a revolutionary metal-free, porous organic catalyst capable of efficiently producing hydrogen fuel (H₂) by harvesting mechanical energy. The pioneering study, led by Professor Tapas K. Maji and his team at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bengaluru, showcases the successful application of a covalent organic framework (COF) with ferrielectric properties for piezocatalytic water splitting — a promising leap in green hydrogen technologies.

The Global Context: Hydrogen as a Sustainable Fuel

The development aligns with the broader goal of mitigating global warming and reducing reliance on fossil fuels. As the world accelerates the transition to renewable energy sources, green hydrogen emerges as a crucial player. It is a clean-burning fuel that, when used in fuel cells, emits only water as a byproduct — eliminating carbon emissions entirely.

Recognizing its transformative potential, the Government of India launched the National Green Hydrogen Mission to scale up H₂ production, enhance research, and establish India as a global hydrogen hub.

Unlocking the Power of Water: Piezocatalytic Water Splitting

Among the several green methods for hydrogen production, overall water splitting is both scalable and efficient. However, it is energetically uphill and necessitates a catalytic process. Piezocatalysis, an emerging technology, converts mechanical energy into chemical energy using piezoelectric materials to split water into hydrogen and oxygen.

While traditionally such piezocatalysts depended on heavy and transition-metal-based ferroelectric (FE) materials, these materials suffer from drawbacks — primarily the quick saturation of catalytic activity due to surface-limited charge generation. The new research shatters this paradigm.

The Breakthrough: Ferrielectric Covalent Organic Framework (FiE-COF)

The team from JNCASR, in collaboration with experts from IISER Pune and Wrocław University of Science and Technology, has created a donor-acceptor COF system utilizing two simple organic molecules: tris(4-aminophenyl)amine (TAPA) as the donor and pyromellitic dianhydride (PDA) as the acceptor.

This COF features imide linkages and exhibits ferrielectric (FiE) ordering, a unique form of electric dipole arrangement. The TAPA molecules, with their propeller-like twisted benzene rings, induce structural asymmetry. This distortion leads to a lower-energy configuration, helping achieve dipole formation across the framework. These dipoles are not only stable but also sensitive to external mechanical perturbations, which is the key to their functionality.

What makes FiE-COFs particularly effective is their ability to generate multiple charge carriers distributed across internal pore surfaces. Unlike conventional FE materials, these FiE dipoles interact intimately with molecular distortions and respond actively to mechanical stimuli, enabling superior piezocatalytic water splitting.

Theoretical Insights and Computational Validation

Professor Umesh V. Waghmare and his research group, also from JNCASR, contributed detailed theoretical modeling to the study. Their computational analysis revealed how dipolar interactions lead to lattice instabilities, promoting FiE behavior. They also demonstrated how energy bands in the COF couple and resonate due to dipolar ordering, enabling effective generation and separation of charge carriers upon mechanical stress.

This resonant band structure, in turn, facilitates the generation of electron-hole pairs, which are critical for initiating the water-splitting reaction.

Performance and Practical Implications

The COF’s porous structure allows water molecules to diffuse efficiently throughout the material, ensuring comprehensive utilization of generated charge carriers. As a result, this metal-free catalyst not only performs water splitting effectively but also delivers ultra-high hydrogen yields, surpassing all known oxide-based inorganic piezocatalysts.

Moreover, the use of inexpensive, earth-abundant organic molecules over scarce and expensive metals drastically lowers production costs, enhancing commercial viability.

A Collaborative Triumph

This research is a result of an interdisciplinary collaboration involving:

• JNCASR Bengaluru: Prof. Tapas K. Maji, Prof. Umesh V. Waghmare, and researchers Adrija Ghosh, Surabhi Menon, Dr. Sandip Biswas, and Dr. Anupam Dey.

• IISER Pune: Dr. Supriya Sahoo and Prof. Ramamoorthy Boomishankar.

• Wrocław University of Science and Technology, Poland: Prof. Jan K. Zaręba.

Their combined expertise in materials chemistry, theoretical physics, and catalysis created a powerful synergy leading to this innovation.

Future Prospects and Impact

The development of a cost-effective, metal-free catalyst that harnesses mechanical energy opens up new avenues for decentralized and off-grid hydrogen production systems — particularly useful in remote or infrastructure-limited regions.

Such innovations strongly support India’s green hydrogen ambitions and could position the country at the forefront of next-generation clean energy technologies. This approach also holds promise for integration into wearable or structural materials where mechanical motions (e.g., human movement, wind, or vibrations) can be used as sustainable energy inputs.

With hydrogen poised to be a cornerstone of the global clean energy transition, innovations like this metal-free COF piezocatalyst represent a bold step into a future powered by green molecules.