New photocatalyst to boost solar energy conversion

Researchers from Engineering at Illinois have set their sights on improving the materials that make solar energy conversion possible.

The researchers have developed a new form of high-performance solar photocatalyst based on the combination of the TiO₂ (titanium dioxide) and other ‘metallic’ oxides that greatly enhance the visible light absorption and promote more efficient utilisation of the solar spectrum for energy applications.

“Our research group incorporates aspects of condensed matter physics, semiconductor device engineering, and photochemistry to make new performance possible. From these materials we can imagine carbon-neutral energy production of clean-burning fuels, wastewater purification and remediation, and much more,” explained Lane Martin, who is an assistant professor in the Department of Materials Science and Engineering at Illinois.

"As a follow-up to our prior work, we expanded our discovery of new, strongly absorbing energy materials," Martin added.

"The overall concept is that we have developed a new form of high-performance solar photo catalyst based on the combination of the TiO₂ and ‘metallic’ oxides." The group’s paper appears in the Advanced Materials journal. The researchers also have a patent application pending for this work.

According to Martin the research paper addresses the most pressing limiting factor of these materials for applications - their poor absorption of light. “This paper covers several new variations where we integrate chemically compatible correlated ‘metallic’ oxides with the model n-type, wide-band gap oxide semiconductor TiO₂ to produce high-performance photocatalytic heterojunctions. These composite structures operate on the principle of hot carrier injection from the ‘metallic’ oxide into the TiO₂.”

These effects are made possible by harnessing the diverse range of correlated electron physics of common metallic oxide materials including n-type LaNiO3 (lanthanum nickelate), SrRuO3 (strontium ruthenate), and SrVO3 (strontium vanadate) and p-type La0.5Sr0.5CoO3 (lanthanum strontium cobaltite) and La0.7Sr0.3MnO3 (lanthanum strontium manganite). These materials have been extensively explored (individually) for their novel electronic transport, magnetic properties and other exotic physical phenomena and are widely utilised as epitaxial bottom electrodes in ferroic heterostructures.

Martin noted that one of the new materials studied (La 0.5Sr0.5CoO3-based devices) demonstrated photocatalytic activities that are 27-, 6.2-, and 3-times larger than that for a single-layer TiO₂ film, nanopowder Degussa P25 samples, and the prior report of devices based on SrRuO3, respectively.