Amino acid trick boosts metal-free solar hydrogen output

Hydrogen is a promising clean fuel, but producing it sustainably often requires expensive metals and complex materials. Now, scientists in Bengaluru have demonstrated a simpler approach using only organic molecules.

A team at the Centre for Nano and Soft Matter Sciences (CeNS), an autonomous institute under the Department of Science and Technology, combined aspartic acid, a naturally occurring amino acid, with perylene diimide (PDI), a light-absorbing organic dye. The key was allowing these molecules to arrange themselves spontaneously in water into highly ordered two-dimensional nanosheets.

This self-assembly, driven by hydrogen bonding from the amino acid and π–π stacking from the dye, dramatically improved the material's performance. The organized structure broadened light absorption, enhanced charge separation, and increased the surface area available for catalytic reactions—all without changing the molecule's chemical makeup.

In tests, the self-assembled material generated nearly 18% more photocurrent than its bulk counterpart during solar-driven water splitting. Advanced electrochemical measurements and density functional theory calculations revealed that self-assembly promotes efficient charge transport, while the amino acid increases the molecular dipole moment, aiding the separation of photo-generated charges.

The findings, published in the Journal of Materials Chemistry A, suggest that naturally occurring amino acids can act as powerful regulators of molecular organization and photocatalytic performance. This design strategy offers a sustainable route to efficient, metal-free photocatalysts for solar energy conversion, with potential applications in green hydrogen production, artificial photosynthesis, and next-generation renewable energy devices.