Organic semiconductor leads to efficient energy storage
18 Feb 2020
An organic semiconductor photocatalyst that significantly enhances the generation of hydrogen gas could lead to more efficient energy storage technologies.
A team led by Iain McCulloch from the King Abdullah University of Science and technology in Saudi Arabia have incorporated hydrogen photocatalysts into organic nanoparticles that can be tuned to absorb more of the visible light spectrum.
Jan Kosco first author of the study said: “Traditionally, inorganic semiconductors have been used for photocatalytic applications. However, these materials absorb primarily UV light, which comprises less than five percent of the solar spectrum. Therefore, their efficiency is limited.”
A standard method for storing solar energy is in the chemical bonds of molecular hydrogen using hydrogen evolution photocatalysts (HEPs). Currently, most HEPs are made from single-component inorganic semiconductors. These can only absorb light at ultraviolet wavelengths, which limits their ability to produce hydrogen.
To make their combined solution, the team used a method called miniemulsion. A solution of the organic semiconductors is emulsified in water with the aid of a stabilising surfactant. They then heated the emulsion to drive off the solvent, leaving behind surfactant-stabilised organic semiconductor nanoparticles.
By varying the surfactant, they were able to control the structure of the nanoparticles, transforming them from a core-shell structure to a mixed donor/acceptor structure. These HEPs exhibited hydrogen evolution rates an order of magnitude beyond what is currently achievable with single-component inorganic HEPs. This lays the foundations for next-generation energy storage technologies.