The ability of the leaf to transform sunlight, carbon dioxide, and water into energy makes it one of nature’s most impressive machines. Researchers at the University of Cambridge have developed an artificial leaf that can float on water and utilize the sunlight and air above it and the water below it to produce cleaner fuels as effectively as a real leaf.
The new research extends the team’s previous work on an artificial leaf that would absorb water and carbon dioxide to produce oxygen, hydrogen, and carbon monoxide using two perovskite light absorbers and a cobalt catalyst. The hydrogen and carbon monoxide could then be collected and used to create synthetic gas (syngas), a vital component of polymers, fertilizers, and liquid fuels like diesel, effectively lowering the CO2 footprint of those goods.
However, the original version was a freestanding device with thick glass and other features that made it rather bulky. The latest study, published on Wednesday in the journal Nature, aimed to make it lighter and thinner without sacrificing effectiveness. It had to be light enough to be able to float on water.
To achieve this, the scientists used a platinum catalyst to deposit light-absorbing perovskite layers onto thin, flexible layers of polyester covered in indium tin oxide. These were then wrapped with ultra-thin, water-repellent, ultra-thin carbon-based materials to protect the equipment from moisture damage.
The final product was a synthetic leaf that could create fuels from water by dividing water into hydrogen and oxygen or produce the ingredients for syngas while floating on the water’s surface. The scientists tested the devices on nearby rivers and found that their output, at 0.053% for carbon monoxide and 0.58% for hydrogen per gram, was comparable to that of natural leaves. Although those figures don’t seem like much, they are a significant advancement over the prior version.
The floating artificial leaves are also scalable. The performance of the artificial leaves was scaled with the size of the versions tested, which ranged from 0.3 in2 (1.7 cm2) to 15.5 in2 (100 cm2). According to the team, the devices could be used to produce cleaner fuels practically anywhere there is water, even on contaminated waterways or the open ocean.
Cargo ships account for approximately 80 percent of global shipping traffic, but they’ve been largely ignored when discussing the climate crisis. Commercial applications of solar fuel production can help the shipping industry to lower its dependence on fossil fuels and lower carbon emissions. Instead, creating clean fuel that does not require space on land.
