Researchers at Rice University were able to create such an efficient and (more importantly) low-cost device with the same function as the existing artificial leaf: splitting water using light and producing fuel (hydrogen) and electricity.
The research was led by engineer Jia Liang, a member of Lou’s research group who, last year, promoted changes in perovskite solar cells. This crystal has cubic structures and is recognized as an excellent light collector (it has efficiency above 25% in converting solar energy into electricity). Your problem: becoming unstable in environments with humidity and heat – in addition to being an expensive material.
“The integrated module transforms sunlight into electricity, generating an electrochemical reaction to obtain fuel. It is the same concept as the artificial leaf, but unstable outdoors,” explained the materials engineer and one of the authors of the work, Jun Lou.
Stability under the sun
In December 2019, the team started testing new materials. In doing so, he managed to make the cells, which tended to fail quickly because of this instability, become 12% more efficient and stable: prepared in environmental conditions, resisted the high humidity of Houston, Texas and remained intact outdoors for more than two months, unlike the previous model, which could not resist a few days of operation.
Basically, the developed platform integrates catalytic electrodes and perovskite solar cells. Exposed to sunlight, the mineral’s cells produce an electrical current, which flows to the catalysts. These transform water into hydrogen and oxygen.
The novelty is right there: Liang’s team joined the perovskite crystals and electrodes in a single module. When immersed in water and exposed to the sun, it produces hydrogen without the need for external energy.
“Liang has replaced the more expensive components of solar cells, such as platinum, with alternatives like carbon. This has dropped one of the main barriers to large-scale commercial production,” explained Lou.
The best is in the packaging
The polymer that encapsulates the solar cell is the star of the system, protecting the module and allowing its immersion for long periods – unlike other catalytic systems, in which only the electrodes are immersed in water, connecting to the solar cell by wires.
“We use an ionomer film, which allows sunlight to reach the system while protecting it, while also serving as an insulator between the cells and the electrodes,” explained Liang.
The group’s perspective is that the system feeds itself. “It is possible to create a self-sustaining loop, even without sunlight. Just use the stored energy as a chemical fuel, placing hydrogen and oxygen in separate tanks and incorporating a third module into the system, which would transform these two elements back into electricity. ”