Optimization of hydrogen evolution reaction catalytic activity of Ti2CO2 via surface engineering with an isolated fluorine effect: An ab-initio density functional theory study

Abstract

MXenes have potential as a hydrogen evolution reaction (HER) catalyst based on their large surface area and excellent electrical properties. In this study, the change in HER catalytic properties according to the surface state of Ti2C-based MXene was analyzed theoretically based on first principles calculation. It was confirmed that the reactivity of the surrounding active sites is enhanced by the influence of isolated fluorine. The mechanism of this phenomenon was investigated, focusing on the electron migration and structural changes. In the MXene family, the Ti2C-based MXene best utilized the isolated fluorine effect. It was found that Ti2CO2 functionalized with a small amount of fluorine was superior as a HER catalyst to Ti2CO2 fully functionalized with oxygen, and the optimal proportion of fluorine was 1.5 to 3%.