VATIS UPDATE Article

A group of researchers led by Takashi Tachikawa from Kobe University, Japan, and Tetsuro Majima from Osaka University, Japan, has developed a photocatalyst that can make hydrogen production ten times more efficient. In their study, researchers described a photocatalyst that increases the production of hydrogen tenfold. When light is applied to photocatalysts, electrons and holes are produced on the surface of the catalyst, and hydrogen is obtained when these electrons reduce the hydrogen ions in water.

However, in traditional photocatalysts the holes that are produced at the same time as the electrons mostly recombine on the surface of the catalyst and disappear, making it difficult to increase conversion efficiency. Instead, Tachikawa’s research group developed a photocatalyst made of mesocrystal, a type of crystal that lacks the uniformity of regular crystals. This new photocatalyst is able to spatially separate the electrons and electron holes to prevent them recombining.

As a result, it has a far more efficient conversion rate for producing hydrogen than conventional nanoparticulate photocatalysts. By first using titanium oxide (TiO2), they were able to synthesize mesocrystal strontium titanate (SrTiO3) using a simple one-step hydrothermal reaction. By lengthening the reaction time, they could also grow larger particles near the surface while preserving their crystalline structure. When they attached a co-catalyst to the synthesized mesocrystal and applied ultraviolet light in water, the reaction occurred with approximately 7% light energy conversion efficiency.