New wonder material is a game-changer

An international team led by scientists at Rice University in Texas, has unveiled a new wonder material that could, when paired with titanium dioxide, be a game-changer for solar fuel generation.

The wafer-thin, two-dimensional material hematene is extracted from hematite, the mineral form of iron ore. Hematite was known to have photocatalytic properties, meaning light accelerates or creates some form of chemical reaction. However, these properties weren’t good enough to have any useful application.

The research showed that the extracted hematene paired with nanotubes of titanium dioxide had more efficient photocatalytic properties. The titanium dioxide nanotube allowed electrical charges generated from photocatalytic activity to be extracted for use.

The research team said that the titanium dioxide nanotube arrays provided an easy pathway for electrons to leave hematene, allowing more visible light to be absorbed.

“For a material to be an efficient photocatalyst, it should absorb the visible part of sunlight, generate electrical charges and transport them to the surface of the material to carry out the desired reaction,” said Oomman Varghese, a co-author and associate professor of physics at the University of Houston.

This efficient process means the material has potential of use in solar energy generation.

The atoms in hematite and hematene are held together in 3D bonding networks. This makes it a rare and stronger material compared to other 2D materials such as graphene. Graphene is a van der Waals materials where atoms are connected by distance-dependent forces which can be relatively weak or susceptible to disruption.

Titanium dioxide is a non-toxic, environmentally friendly and corrosion-resistant material; formed into nanotube arrays increases the surface area of titanium dioxide enhancing its valuable properties, including its semiconductor properties. It is used in dye-sensitized solar cells used for solar energy, known as Grätzell cells.

“Here, we have a simple, scalable method, and the hematene structure should be environmentally stable,” said Pulickel Ajayan chair of Rice University’s Department of Materials Science and NanoEngineering.

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