Sunlight is crucial for life on Earth, as it provides energy for plants, warmth for animals, and vitamin D for humans. It also drives the Earth’s seasons, ocean currents, and weather patterns. The sun releases more energy in 1.5 millionths of a second than all humans consume in an entire year. Now, for the first time in history, sunlight has been converted into energy, and it’s the most powerful source ever seen.
The device that uses sunlight in a historic way
Engineers from Rice University in Houston, Texas, made history after turning sunlight into green hydrogen with a record-breaking efficiency thanks to their device that combines next-generation halide perovskite semiconductors with electrocatalysts in a single, sturdy, economical, and scalable device.
The engineers called the device a photoelectrochemical cell due to its ability to absorb sunlight, convert it into electricity, and use the electricity to initiate a chemical reaction, which all takes place in one device. Before the historic breakthrough, photoelectrochemical technology could only produce green hydrogen with extremely low efficiencies and expensive semiconductors.
“Using sunlight as an energy source to manufacture chemicals is one of the largest hurdles to a clean energy economy. Our goal is to build economically feasible platforms that can generate solar-derived fuels. Here, we designed a system that absorbs light and completes electrochemical water-splitting chemistry on its surface.” – Austin Fehr, a chemical and biomolecular engineering doctoral student and one of the study’s lead authors
This is how the device converts sunlight into energy
The Mohite lab and its team turned their highly competitive solar cell into a reactor to use harvested energy from sunlight to split water into oxygen and hydrogen. The hurdle in their way was that halide perovskites are extremely unstable in water, and the coatings used to envelope the semiconductors ended up either disrupting their function or impairing them.
Aditya Mohite, the lab chemical and biomolecular engineer, overcame the hurdle by manufacturing the integrated device utilizing an anticorrosion barrier that envelopes the semiconductor from water without disrupting electron transfer.
“Our key insight was that you needed two layers to the barrier, one to block the water and one to make good electrical contact between the perovskite layers and the protective layer. Our results are the highest efficiency for photoelectrochemical cells without solar concentration, and the best overall for those using halide perovskite semiconductor.” – Fehr
The results are historic and efficient
Per the study published in Nature Communications, the photoelectrochemical cell achieved 20.8% solar-to-hydrogen conversion efficiency and 102 h of continuous operation before t60 under AM 1.5G illumination. The research team indicated that their barrier design was successful in various reactions and with different semiconductors, which gives it a high application potential across many systems.
According to Fehr, if they continue to improve the device’s stability and scale, it may open up the hydrogen economy and change the way humans make things from fossil fuel to solar fuel. These improvements will lead to efficient, sturdy, and economical solar-driven water-splitting devices with multifunctional barriers.
“All devices of this type produce green hydrogen using only sunlight and water, but ours is exceptional because it has record-breaking efficiency and it uses a semiconductor that is very cheap.” – Fehr
The newly created device proves to be a noteworthy step forward for clean energy solutions and may even serve as a platform for various chemical reactions that utilize solar-harvested electricity to convert feedstocks into fuels. Rice graduate students Ayush Agrawal and Faiz Mandani are the lead authors of the study alongside Fehr. For more information about the research, you can check the full study: Fehr, A.M.K., Agrawal, A., Mandani, F. et al. Integrated halide perovskite photoelectrochemical cells with solar-driven water-splitting efficiency of 20.8%. Nat Commun 14, 3797 (2023)