Single Pt atoms stabilized on MoTiCO for hydrogen evolution: A first-principles investigation.

Single-atom catalysis offers an effective way to reduce the amount of used noble metals and maximizes their catalytic activity. We systematically explore electrocatalytic performances of Pt doped MoTiCO monolayer by the first principles calculations. Our results show that the presence of donor defects in MoTiCO can always increase the reaction free energy of hydrogen adsorption and further promotes the performance in hydrogen evolution reaction (HER). More interestingly, the substitution of Pt for O in the MoTiC can modify the free energy to an ideal value and is responsible for the significantly enhanced catalytic activity. Furthermore, the large value of diffusion barrier indicates that single Pt atoms can be stabilized onto the O vacancy sites, which can effectively prevent them to aggregate into nanoparticles. Our works are useful for understanding the recent experimental observations and pave the way for further experimental improvements of catalytic activity for the HER.