Inspenet, July 31, 2023.
Rice University engineers have achieved a record 20.8% efficiency in converting solar energy into hydrogen using an innovative device. This photoreactor combines perovskite halide semiconductors with electrocatalysts, creating a durable, economical, and scalable device. This new technology represents a significant advance in clean energy and may pave the way for various chemical reactions that use solar energy to convert raw materials into fuels.
Chemical engineer Aditya Mohite’s team built the photoreactor embedded with an anti-corrosion barrier that isolates the semiconductor from water without disrupting electron transfer. This achievement has been documented in a study published in Nature Communications.
“Using sunlight as an energy source to make chemicals is one of the biggest obstacles to a clean energy economy,” says Austin Fehr, a chemical and biomolecular engineering doctoral student and one of the study’s lead authors. “Our goal is to build economically viable platforms that can generate fuels derived from solar energy. Here we designed a system that absorbs light and completes the electrochemical chemistry of separating water on its surface.”
Advances and challenges of this new device
The aforementioned device is a photoelectrochemical cell that has the particularity of carrying out three processes in the same device: absorbing light, converting it into electricity, and using that electricity to drive a chemical reaction. Until this breakthrough, the photoelectrochemical technology to produce green hydrogen faced challenges due to the low efficiency and high cost of the semiconductors used.
“All devices of this type produce green hydrogen using only sunlight and water, but ours is exceptional because it has record efficiency and uses a semiconductor that is very cheap,” says Fehr.
Mohite’s team and collaborators succeeded in transforming their highly competitive solar cell into a reactor capable of using the collected energy to break down water into oxygen and hydrogen . The challenge they faced was the instability of the halide perovskites in water, and the coatings used to protect the semiconductors ended up affecting their operation or damaging them.
After long tests that did not give the desired result, the researchers finally came up with a winning solution. “Our key insight was that two layers were needed in the barrier, one to block the water and one to establish good electrical contact between the perovskite layers and the protective layer,” Fehr explains. “Our results are the most efficient for non-concentrating photoelectrochemical cells and the best overall for those using perovskite halide semiconductors.”
The researchers proved that their barrier design was effective in various reactions and with different semiconductors, meaning it is applicable to a wide range of systems. “We hope that these systems will serve as a platform to drive a wide range of electron fuel-forming reactions using abundant raw materials with only sunlight as an energy input,” says Mohite.
“With further improvements in stability and scale, this technology could open up the hydrogen economy and change the way humans make things from fossil fuel to solar,” Fehr added.
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