Researchers at Northwestern University have developed a new class of bioinspired materials capable of capturing solar energy, storing it for months, and releasing it on demand, all without metals, critical minerals, or plastic polymers.
Bioinspired materials that mimic nature’s energy systems
A “perfect” material capable not only of capturing solar energy but also of storing and releasing it when needed. That is the goal pursued by a team of scientists at Northwestern University, who have developed a new chemical system inspired by nature to support future energy technologies, all without relying on metals, critical materials, or synthetic plastic polymers.
The secret behind the breakthrough is tiny, incredibly tiny. To create the new advanced material, the researchers drew inspiration from the cytoskeleton, the network of protein filaments and tubules that forms the internal framework of living cells. This intricate structure emerges through a self-assembly process in which individual protein building blocks, known as monomers, continuously join and separate from long filaments, consuming and releasing energy along the way.
The new Northwestern material behaves in a similar manner, repeatedly assembling and disassembling in response to external stimuli.
“The system exhibits functions distinct from biological systems while leveraging useful energy storage and release as molecules assemble and disassemble under various stimuli, including light, chemical fuels, electricity, and X-rays,” the researchers explain.
ANI-MV and a new approach to energy storage
The work began with the design of a new artificial monomer called ANI-MV. The molecule combines two key components: a chromophore, aminonaphthalene (ANI), capable of absorbing light and donating electrons, and methyl viologen (MV), a molecule known for its ability to accept electrons.
In solution, the material appears as a simple yellow liquid. When exposed to sunlight, however, the monomers polymerize into a supramolecular system, forming a black gel. During this transformation, energy becomes trapped within newly formed chemical bonds and can remain stored for months.
“As the MV unit becomes enriched with electrons, neighboring molecules strongly attract one another, forming structures known as pimers. These pimers then organize into nanoscale semiconducting ribbons with delocalized electrons, meaning the electrons can move freely throughout the structure instead of remaining confined,” explained Amanda Morris.
“When the ribbons become entangled, they form a black gel that stores electrons across its molecular network. These ribbons represent the first example of a supramolecular polymeric pimer, a self-assembled material composed of paired molecules that store electrons.”
A chemical battery inspired by living cells
One of the most remarkable characteristics of the material is its ability to reverse the process, effectively acting as a chemical battery.
When exposed to air, the gel releases its stored electrons by transferring them to surrounding oxygen. This interaction generates reactive oxygen species (ROS), highly energetic and reactive molecules that can be used to drive chemical reactions.
According to the researchers, just one gram of the material could store enough energy to charge a smartwatch or another wearable electronic device.
The study highlights the growing potential of bioinspired materials as a new frontier for solar energy harvesting and storage. By emulating nature’s dynamic molecular systems, scientists may be able to develop sustainable energy technologies that avoid dependence on critical minerals while offering long-term energy storage capabilities.
