A composite photocatalyst fabrication technology has been developed to improve removal of aquatic pollutants such as antibiotics entering rivers and to increase the efficiency of eco-friendly hydrogen production from water. 

The National Research Foundation of Korea (Chairperson Lee Kwang-bok) announced that the research team of Professor Seunghwa Yoo at Jeonbuk National University (JBNU) has succeeded in developing a composite photocatalyst that maximizes performance by combining layered double hydroxides (LDH)* with the cocatalyst MXene. Layered double hydroxides are ionic solids with a [AcB Z AcB]n layered structure, where c denotes metal cations, A and B are hydroxide anion (OH-) layers, and Z is another cation or a neutral molecular layer such as water. A photocatalyst is a compound that absorbs light energy to initiate and promote photochemical reactions.

Recently, various photocatalyst studies have progressed in environmental and energy fields, such as removal of organic pollutants in water and production of clean hydrogen energy. However, most photocatalysts have insufficient activity, making practical use difficult. To enhance photocatalytic activity, efficient charge transfer at interfaces where dissimilar nanomaterials join, sufficient transport channels, and abundant active sites must be secured.  

The team synthesized a layered double hydroxide combining cobalt (Co) and iron (Fe) and a Ti3C2 MXene composed of titanium (Ti) and carbon (C), then developed a new photocatalyst fabrication method in which these materials are subjected to hydrothermal synthesis (a method of crystallizing materials from high-temperature aqueous solutions under high vapor pressure) with a chromium (Cr) precursor. The team confirmed that cobalt-iron-chromium oxide (CoFeCrO4) nanoparticles grew simultaneously in situ on the surface of the cobalt-iron LDH (CoFe-LDH). 

A Schottky barrier formed at the heterojunction (CoFe-LDH/CoFeCrO4) interface, increasing the separation efficiency of photogenerated charge carriers. In addition, the heterojunction (CoFe-LDH/CoFeCrO4) and the Ti3C2 MXene, once combined, formed an electron band structure suitable for a composite photocatalyst and provided ample active sites. 

Professor Seunghwa Yoo said, 'The composite photocatalyst developed in this study is expected to be applicable to various fields including environment and energy,' and added, 'We plan to pursue additional research to enable fabrication in various forms such as substrates and pellets to lay the groundwork for commercialization.'    

This research, carried out under the Regional University Outstanding Scientist and Basic Research Laboratory support programs promoted by the Ministry of Science and ICT and the National Research Foundation of Korea, was published online on April 1 in the international journal Composites Part B: Engineering in the fields of engineering and materials science.