How a revolutionary multi-charge storage molecule could transform solar energy into storable fuel
Imagine a future where the fuels that power our cars, heat our homes, and fuel our industries are created from nothing more than sunlight, water, and the carbon dioxide already in our air. This isn't science fiction—it's the promising frontier of artificial photosynthesis, a technology that aims to mimic nature's masterful recipe for converting sunlight into stored chemical energy. While plants have perfected this process over billions of years to produce carbohydrates, scientists are now reengineering it to create carbon-neutral fuels that could wean our civilization off fossil fuels.
The amount of solar energy reaching Earth in one hour is more than the total energy consumed by humanity in an entire year. Artificial photosynthesis could help us capture and store this abundant resource effectively.
The quest for artificial photosynthesis represents one of science's most ambitious challenges: outperforming nature in efficiency while providing sustainable, storable energy for human civilization. For decades, this goal remained elusive, confined to theoretical models and inefficient laboratory demonstrations. But recent breakthroughs have transformed this field, bringing us closer than ever to realizing what many consider the holy grail of clean energy. This is the story of how persistent innovation across global laboratories has produced a landmark achievement that could fundamentally reshape our energy landscape.
Natural photosynthesis is the remarkable process that sustains nearly all life on Earth. Plants, algae, and certain bacteria use chlorophyll in specialized structures called photosystems to capture sunlight and transform carbon dioxide and water into glucose and oxygen 4 .
Artificial photosynthesis takes inspiration from this natural blueprint but with crucial modifications. Instead of producing carbohydrates, artificial systems are designed to generate energy-dense fuels like hydrogen, methanol, methane, or synthetic gasoline 1 5 .
While solar panels have made remarkable strides in converting sunlight to electricity, they face a significant limitation: energy storage. Solar panels only generate electricity when the sun shines, and storing this electricity efficiently for later use remains challenging 1 .
Artificial photosynthesis addresses this fundamental problem by producing liquid and gas fuels that can be easily stored, transported, and used on demand—making them particularly valuable for industries like aviation, shipping, and heavy manufacturing that cannot easily transition to electricity 1 .
Typical efficiency: 3-6%
Potential efficiency: >20%
| Aspect | Natural Photosynthesis | Artificial Photosynthesis |
|---|---|---|
| Primary Product | Carbohydrates (sugars) | Hydrogen, methanol, methane, or other solar fuels |
| Energy Storage | Chemical energy in sugars | Chemical energy in fuels |
| Efficiency | 3-6% | Variable, potentially higher but still under development |
| Carbon Impact | Carbon neutral | Potentially carbon neutral |
| Primary Applications | Food and biomass production | Fuel for energy, industry, and transportation |
The path to efficient artificial photosynthesis has been hampered by a persistent scientific challenge: storing multiple charges simultaneously. In natural photosynthesis, plants expertly manage the accumulation and transfer of multiple electrons to drive chemical reactions.
Replicating this capability in artificial systems has proven difficult, as molecules capable of storing the necessary multiple charges typically required intense laser light and couldn't maintain their charges long enough to be useful for fuel production 1 6 .
In August 2024, a research team at the University of Basel led by Professor Oliver Wenger and doctoral student Mathis Brändlin announced a groundbreaking solution: a specially engineered molecule that can store two positive and two negative charges simultaneously when exposed to light 1 6 .
This development, published in the prestigious journal Nature Chemistry, represents the most significant advancement in artificial photosynthesis in recent years.
"We have identified and implemented an important piece of the puzzle."
Reaction initiator component
Provide positive charges
Provide negative charges
Opposite ends of molecule
Researchers first designed and synthesized the complex five-component molecule, carefully engineering its structure to enable efficient charge separation and storage.
The team exposed the molecule to two sequential flashes of light rather than continuous illumination. The first flash triggered an initial electron transfer, creating one positive and one negative charge that migrated to opposite ends of the molecule.
A second flash of light repeated this process, generating an additional positive and negative charge. After both flashes, the molecule contained two positive charges on one side and two negative charges on the other 6 .
Researchers measured how long the molecule maintained these charges, confirming they remained stable long enough to potentially drive fuel-producing chemical reactions.
Crucially, the team demonstrated that this process worked effectively with light intensities approaching that of natural sunlight, a vast improvement over previous systems that required powerful lasers 6 .
Simultaneous storage of two positive and two negative charges
Works with light intensity approaching sunlight
Charges remain stable long enough for chemical reactions
| Parameter | Previous Artificial Photosynthesis Systems | Basel Molecular System |
|---|---|---|
| Light Requirement | Required intense laser light | Works with light approaching sunlight intensity |
| Charge Storage Capacity | Typically single charge pairs | Two positive and two negative charges simultaneously |
| Charge Stability | Often too brief for practical use | Sufficiently long for potential use in chemical reactions |
| Energy Conversion Efficiency | Generally low | Significantly improved, though not yet quantified for full process |
"This stepwise excitation makes it possible to use significantly dimmer light. As a result, we are already moving close to the intensity of sunlight."
The progress in artificial photosynthesis relies on increasingly sophisticated materials and components, each serving specific functions in the complex process of converting sunlight to chemical fuel.
| Material/Catalyst | Primary Function | Key Characteristics | Current Research Applications |
|---|---|---|---|
| Metal-Organic Frameworks (MOFs) | Provide structured environment for reactions with maximum surface area | Highly tunable porous materials | University of Chicago team added amino acids to MOFs to improve reaction efficiency |
| Perovskite Photoabsorbers | Capture light energy similar to chlorophyll in plants 3 | Excellent light-absorption properties | Used in Lawrence Berkeley Lab's "artificial leaf" to convert CO₂ to valuable C2 products 3 |
| Copper-based Catalysts | Convert carbon dioxide into carbon-based fuels and chemicals 3 | More durable than biological alternatives | Berkeley Lab's system produces C2 precursors for plastics and jet fuel 3 |
| Cobalt Compounds | Facilitate electron transfer in reactions | Effective electron shuttle | Used in multiple systems including University of Chicago's approach for methane production |
| Rhodium-Chromium-Cobalt-loaded Semiconductors | Enable hydrogen evolution through water splitting 2 | Highly efficient for overall water splitting | Employed in artificial photosynthesis directed toward organic synthesis (APOS) 2 |
This diverse toolkit reflects the interdisciplinary nature of artificial photosynthesis research, drawing from chemistry, materials science, engineering, and biology to create integrated systems that approach the sophistication of natural photosynthesis.
Research in artificial photosynthesis is advancing through global collaboration between universities, national laboratories, and private institutions, accelerating progress through shared knowledge and resources.
The recent breakthrough in multi-charge storage molecules at the University of Basel represents more than just an incremental advance—it signals a maturation of artificial photosynthesis from theoretical concept toward practical technology. When viewed alongside parallel progress in materials science, catalyst design, and system integration across global research institutions, it becomes clear that we are witnessing the emergence of a viable pathway to solar-powered fuels.
"We hope that this will help us contribute to new prospects for a sustainable energy future."
While significant challenges remain in scaling up these systems and improving their efficiency, the recent pace of innovation suggests that artificial photosynthesis may play a crucial role in our clean energy future. The success story of artificial photosynthesis is still being written, but each breakthrough brings us closer to harnessing the abundant energy of the sun in a form that can power our civilization without compromising our planet.