Density functional theory study of adsorption and diffusion of potassium atoms on zigzag graphene nanoribbons with different terminal groups

Despite the extensive use of graphene-based materials in K-ion batteries, the effects of various edge morphologies of graphene on K atom adsorption and diffusion are unclear. In this study, the effects of K atom adsorption and diffusion on zigzag graphene nanoribbons (ZGNRs) with hydrogen (-H), ketone (=O), hydroxyl (-OH), and carboxyl (-COOH) terminal groups were investigated by density functional theory calculations. ZGNRs terminating with -H, =O and -COOH promote K atom adsorption, whereas those terminating with -OH suppress it. The -H, =O, -OH and -COOH terminations have a negligible effect on K atom diffusion in the inner region of ZGNRs. In the edge region, the diffusion barriers are nearly unchanged for -H and -OH terminations; however, they are increased for =O and -COOH terminations in the edge region compared to those in the inner region. All the terminal groups hinder K atom diffusion from the edge region toward the inner region. Our results suggest that -H termination enhances K atom adsorption and has a negligible effect on the diffusion barrier of K atom in the edge region. Therefore, the ZGNR with -H termination could be a promising candidate for K-ion batteries.

Automated summary

This study investigates the effects of different edge morphologies of graphene on potassium atom adsorption and diffusion through density functional theory calculations. The results show that ZGNRs terminating with -H promote potassium atom adsorption and have minimal impact on the diffusion barrier in the edge region.