UNIST researchers have developed a scalable and efficient photoelectrochemical system to produce solar hydrogen commercially.
green hydrogen production Using solar energy directly to split water is one of the most significant achievements in the field of electrochemical technologies today. However, most Photoelectrolyzers proposed so far are unstable or inefficient due to material degradation., And the best results are still limited to small laboratory measurements.
He new photoelectrochemical system The proposal by scientists at the National Institute of Science and Technology in Ulsan, South Korea could revolutionize this field.
The team thoroughly investigated the challenges associated with direct solar hydrogen production by repurposing the recipe from conventional PEC cells. But above all, it has combined all the desired characteristics in one product: high conversion efficiency from Sol to H.2Durability, scalability.
Photoelectrochemical technology for hydrogen production
In photoelectrochemical water splitting, hydrogen is generated using light and special semiconductors, similar to those used in photovoltaic generation but immersed in a water-based electrolyte. The sun’s rays are absorbed by the semiconductor which acts as the anode of the cell and breaks down the H molecules.2O!
PEC reactors can be built as photovoltaic panels with electrode systems or as Particle Suspended Photocatalysts, The former have been most studied by far due to their similarity with photovoltaic technologies. The biggest challenges that must be addressed at this time relate to: efficiency, which must be improved through greater light absorption and better surface catalysis; Durability, which will be optimized through corrosion-resistant materials and protective surface coatings; Production costs, which will be reduced through cheaper materials and processes compared to existing costs.
Recently, technology has been developed that solves the efficiency problem to some extent, but the results are obtained with a small laboratory equipment. “There is a need for expansion to increase the size of marketing.”
Jae-seong Lee, Professor UNIST
UNIST photoelectrolyzer exceeds 10% efficiency
A key aspect of South Korea’s progress is that they have used Perovskite for its photoelectrodes, a material known for its photovoltaic efficiency and relatively cheap. However, on the other hand, as solar cells themselves have shown, most perovskites are particularly sensitive to environmental stress. Especially for ultraviolet rays and humidity. On paper, this is not the best choice for a material that will be used underwater.
Solution? The team produced more UV-stable perovskite using Formamidinium as cation in the molecule instead of the traditional methylammonium. surface in contact with water Fully sealed with nickel foil To avoid corrosion.
and that’s not all. This approach made it possible to increase the size of the photoelectrode. In research applications these components typically measure less than 1 square meter and must be scaled up approximately 10,000 times to reach a practical size for a commercial photoelectrolyzer. To enhance their perovskite photoanode, the team used “module-based design”, which houses small photoelectrodes of a fixed size And then connects them horizontally and vertically. In this way, the device achieved a solar hydrogen conversion efficiency of more than 10% (minimum requirement for commercialization), the highest value achieved so far for a large area photoelectrode.