Breaking Symmetry: Enhanced Hydrogen Evolution Reaction Performance of Janus Zr2COT (T = F, Cl, Br, I) MXenes by Density Functional Theory.

This investigation highlights the significant impact of asymmetric Janus Zr₂COT (T = F, Cl, Br, I) monolayers on enhancing the hydrogen evolution reaction (HER) performance. Employing density functional theory (DFT), our research demonstrates that introducing asymmetric functional groups into Zr₂COT structures effectively tailors their electronic properties, leading to a marked improvement in HER activity. This structural innovation notably reduces the hydrogen adsorption Gibbs free energy (ΔG_H*) from 0.877 eV for the symmetric Zr₂CO₂ to below 0.2 eV for the Janus Zr₂COT configurations, with Zr₂COBr and Zr₂COI achieving exceptionally low ΔG_H* values of 0.045 and −0.042 eV, respectively, at a hydrogen coverage of 1/4. The monolayers also exhibit remarkable thermal stability and superior electrical conductivity, vital for high-efficiency electrocatalysis. Furthermore, strain engineering underscores the durability of these materials, maintaining ΔG_H* values within ±0.2 eV under extensive tensile strain and emphasizing their practical application potential. Crucially, this work uncovers the critical role of electronic structure adjustments in optimizing the HER performance, aligning with the Sabatier principle, and offering fresh perspectives for designing effective, cost-efficient electrocatalysts. In a word, Janus Zr₂COT monolayers emerge as promising candidates, challenging traditional noble metal catalysts and paving the way for the development of sustainable electrocatalytic materials. [ABSTRACT FROM AUTHOR]