Research investigates ways to convert titanium dioxide into a new photoactive material in the visible light range.
The search for clean and renewable energy sources has intensified in recent years due to the increase in atmospheric concentration of greenhouse gases and the consequent increase in the average temperature of the planet. One such alternative source is the conversion of sunlight into electricity through photovoltaic panels. The efficiency in this conversion depends on the intrinsic properties of the materials used in the manufacturing of the panels, and it increases year by year with the discovery of new and better materials. As such, solar energy is expected to become one of the main sources of electric energy by the middle of this century, according to the International Energy Agency (IEA).
Titanium dioxide (TiO2) is an abundant, nontoxic, biologically inert and chemically stable material, known primarily as a white pigment used in paints, cosmetics and even toothpastes. TiO2 is also often used in sunscreens since it is especially capable of absorbing radiation in the ultraviolet region. However, this same property severely limits the use of TiO2 for solar energy conversion, since the ultraviolet emission comprises only 5 to 8% of the total energy of the solar light.
Can this TiO2 property be extended to the visible light region to increase the conversion of sunlight into electricity? To answer this question, Maria Pilar de Lara-Castells et al.  conducted an innovative research in which they discuss how a special treatment can change the optical properties of TiO2.