Materials scientist Jun Lou and colleagues from Rice University developed an “artificial leaf” that makes hydrogen fuel endlessly with only sunlight, water, and catalytic electrodes. Lou said:
The concept is broadly similar to an artificial leaf. What we have is an integrated module that turns sunlight into electricity that drives an electrochemical reaction. It utilizes water and sunlight to get chemical fuels.
The platform uses a perovskite solar cell to absorb sunlight and convert it into electricity. When the current flows to the catalysts, it splits water into hydrogen and oxygen. The entire process is contained within a single module that can be placed in any body of water exposed to sunshine. It then produces hydrogen with no further input. The sunlight-to-hydrogen efficiency is currently at up to 6.7%, but they are working on improving that now.
A highlight about this device is that it is an efficient system that can run for long periods, endlessly producing hydrogen as long as there are water and sunlight. Lou said:
With a clever system design, you can potentially make a self-sustaining loop. Even when there’s no sunlight, you can use stored energy in the form of chemical fuel. You can put the hydrogen and oxygen products in separate tanks and incorporate another module like a fuel cell to turn those fuels back into electricity.
The polymer that encapsulates everything protects the components and allows the device to be immersed for long periods. This is one of the features that set their artificial leaf apart from others. Lou said:
Others have developed catalytic systems that connect the solar cell outside the water to immersed electrodes with a wire. We simplify the system by encapsulating the perovskite layer with a Surlyn (polymer) film. The patterned film allows sunlight to reach the solar cell while protecting it and serves as an insulator between the cells and the electrodes.
The team has also replaced expensive components commonly found in perovskite solar cells to reduce the cost of their artificial foliage, and thus make it more viable for commercial production. Lou said:
Jia has replaced the more expensive components, like platinum, in perovskite solar cells with alternatives like carbon. That lowers the entry barrier for commercial adoption. Integrated devices like this are promising because they create a system that is sustainable. This does not require any external power to keep the module running.
Scientists worldwide have long been inspired by plants’ natural ability to purify the air and produce energy. Among other interesting artificial leaf ideas is one developed to absorb CO2 from the air, and another that converts sunlight, carbon dioxide, and water into synthetic gas.
