Titanium oxide is used in cosmetics, daily necessities, foods, pharmaceuticals, building materials, etc. as white pigments, UV protection materials (scattering materials that mainly reflect and detoxify), and photocatalysts.However, the European Union (EU) designated it as carcinogenic classification category 2020 in 2, and banned the use of food in France.There are no restrictions on its use in Japan, but alternatives have been sought due to its dependence on titanium oxide and the size of the market.

　Dinuclear iron ions coordinated with water (or OH group) exhibit more photocatalytic action than titanium oxide when they absorb UV.It is ubiquitous in nature such as in enzymes and proteins, but it is difficult to synthesize and unstable.Safety and stability were issues as an alternative material to titanium oxide.

　This time, the research team succeeded in stabilizing by embedding dikaryon iron ions inside the porous silica powder (white) with a fine structure.The resulting white UV absorber had reduced harmful photocatalytic activity, and the sunscreen cream using this powder showed performance and stability comparable to current titanium oxide.

　Now that we have obtained a guideline for synthesizing a white UV inhibitor (absorbent that absorbs and detoxifies) with a substance that is safer than titanium oxide, it is expected to be applied to cosmetics and sunscreen creams in the future.Further, depending on the fine structure of the porous silica used for stabilization, the high photocatalytic action of iron dinuclear ions can be maintained, so that it can be applied to a photocatalyst such as an air purifier.

Paper information:[Materials Today Nano] Layered Silicate Stabilises Diiron to Mimic UV-Shielding TiO2 Nanoparticle