Oxygen and chlorine generation without precious metals: Electrode potential changes the MXene surface

MXene is a type of two-dimensional material discovered in 2011. Previous theoretical studies predicted that MXene has no catalytic activity in anodic processes. Researchers led by Professor Kai S. Exner, head of the Department of Theoretical Catalysis and Electrochemistry at the University of Duisburg-Essen (UDE), used multiscale modeling to disprove this theory.

The scientists found that the surface of MXene transformed into a brush-like structure when an electrode potential was applied. Atoms of the non-noble metal move out and form a so-called “SAC-like structure” (single-atom catalyst-like). These catalysts mediate two important reactions: oxygen evolution and chlorine evolution.

The result is a material with catalytically active sites on the surface without the addition of precious metals. “We concluded that MXene behaves similarly to enzymes in an electrochemical environment. By applying an electrode potential, active sites for MXene are created directly in the process,” Exner explained. Masu. The study will be published in the Journal of the American Chemical Society.

The research team was also able to show that the resulting SAC-like structure is selective, meaning that when water and chloride ions are simultaneously in the reaction environment, only gaseous chlorine is produced. . The production of this basic chemical is a key process in the chemical industry, which generates more than 70 million tons of chlorine gas (Cl2) annually. Cl2 is required for pharmaceuticals, plastics, battery manufacturing, and water treatment.

However, when only water is present in the electrolyte, the active MXene surface promotes the production of gaseous oxygen (O2) through oxygen evolution. This is a key step in the production of green hydrogen in an electrolyser.

This discovery could greatly simplify the production of single-atom catalysts. Elimination of expensive precious metals also reduces costs and dependencies.