Enhancing the hydrogen evolution reaction on O-terminated Ti3C2 MXenes via dual non-metal doping: a first-principles study

Abstract

Searching for non-metal-free catalysts for the hydrogen evolution reaction (HER) is crucial to the development of sustainable energy. Here, we systematically designed and investigated the HER catalytic performance of dual non-metal doped Ti₃C₂O₂ using density functional theory (DFT) calculations. The doped catalysts exhibit outstanding HER catalytic performance, with the surface O atoms of doped Ti₃C₂O₂ serving as the active sites. Our results found that the Si–P and Si–As co-doped Ti₃C₂O₂ exhibits outstanding HER performance, with hydrogen adsorption Gibbs free energies of −0.228 eV and −0.226 eV, respectively. These values are significantly superior to those of pristine Ti₃C₂O₂ and surpass the performance of Hf-doped Ti₃C₂O₂. Furthermore, crystal orbital Hamilton population (ICOHP), density of states (DOS), and charge density difference (CDD) analyses reveal the change in the electronic structure of the catalyst surface and enhance its HER activity. This work not only elucidates the mechanistic role of non-metal co-doping in enhancing HER activity but also brings new prospects to the potential of MXenes in HER catalysis.