A research team led by Daegu Gyeongbuk Institute Of Science And Technology (DGIST) Professor Jong-Sung Yu in Korea, with colleagues at UC Berkeley and Xi’an Jiaotong University in China, has successfully developed a new catalyst synthesis method that can efficiently decompose water into oxygen and hydrogen using solar light. A paper on their work is published in the journal Applied Catalysis B: Environment.

The simultaneous reduction and hydrogenation of TiO₂ by [Mg] and [H], respectively, offer efficient hydrogen-doped reduced TiO_2-x photocatalyst systems which exhibit high efficiency (16.1 mmolg⁻¹h⁻¹) for solar hydrogen production from methanol-water in the presence of only 0.25% of photodeposited Pt nanoparticles with excellent performance stability. The photocatalyst system possesses sufficient low recombination of the photogenerated charges and also utilizes a reasonable amount of visible light. Sinhamahapatra et al.

Here we report a gold-colored H-doped TiO_2-x (H:TiO_2-x) nanoparticles prepared by controlled reduction via simultaneous presence of [Mg] and [H], which are obtained from the decomposition of MgH₂. The H-doped TiO_2-x exhibits a significant activity (16.1 mmolg⁻¹h⁻¹) and remarkable stability after Pt deposition for solar-driven H₂ generation from methanol-water.

—Sinhamahapatra et al.

Research is being conducted globally on how to produce hydrogen using solar light and a photocatalyst by decomposing water. To overcome the limitations of photocatalyst that only reacts to light in ultraviolet rays, researchers have doped dual atoms such as Nitrogen (N), Sulfur (S), and Phosphorus (P) on photocatalysts or synthesized new photocatalysts, developing a photocatalyst that reacts efficiently to visible light.

With Professor Samuel Mao’s team at UC Berkeley in the US., Professor Yu’s research team developed a new H-doped photocatalyst by removing oxygen from the photocatalyst surface made of titanium dioxide and filling hydrogen into it through the decomposition of MgH₂.

Energy with long wavelength—including visible light—could not be used for the existing white titanium dioxide because it has a wide band gap energy. However, the development of MgH₂ reduction could overcome this through oxygen flaw induction and H-doping while enabling the use of solar light with 570nm wavelength.

MgH₂ reduction can synthesize new materials by application to titanium oxide, as used in this study, as well as the oxides composed of other atoms such as Zr, Zn, and Fe. This method is also applicable in various other fields—in photocatalysts and secondary batteries, for example. The photocatalyst synthesized in this research has four times higher photoactivity than the existing white titanium dioxide and is not difficult to manufacture, thus being very advantageous for hydrogen mass production.

Another characteristic of the photocatalyst developed by the research team is that it reduces band gap more than the existing titanium dioxide photocatalyst used for hydrogen generation and can maintain four times higher activity with stability for more than 70 days.

The new method can also react to visible light unlike existing photosynthesis, overcoming the limitation of hydrogen production. With the new photocatalyst development, the efficiency and stability of hydrogen production can both be improved.

The photocatalyst developed this time is a synthesis method with much better performance than the existing photocatalyst method used to produce hydrogen. It is a very simple method that will greatly help commercialize hydrogen energy. With a follow-up research on improving the efficiency and economic feasibility of photocatalyst, we will take the lead in creating an environment stable hydrogen energy production that can replace fossil energy.

—Professor Yu

Resources

• Apurba Sinhamahapatra, Ha-Young Lee, Shaohua Shen, Samuel S. Mao, Jong-Sung Yu (2018) “H-doped TiO_2-x prepared with MgH₂ for highly efficient solar-driven hydrogen production,” Applied Catalysis B: Environmental, Volume 237, Pages 613-621 doi: 10.1016/j.apcatb.2018.06.030