A DFT study on regulating the active center of v-Ti₂XT₂ MXene through surface modification for efficient nitrogen...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Electrochemical nitrogen reduction reaction (NRR) offers a sustainable alternative to the Haber-Bosch process.
• Developing high-performance catalysts and understanding NRR mechanisms are critical challenges.

Purpose of the Study:

• To systematically investigate the NRR performance and mechanism of 24 Ti₂XT₂ MXenes with a T-vacancy.
• To explore the influence of surface functional terminations and non-metallic center elements on NRR activity.
• To provide insights for designing efficient electrocatalysts for ammonia synthesis.

Main Methods:

• Systematic theoretical calculations (DFT) were performed on 24 Ti₂XT₂ MXenes.
• Analysis included charge density difference, orbital interactions, and free energy changes.
• The work function was investigated as a descriptor for catalytic performance.

Main Results:

• Surface functionalization significantly reduced the limiting potential for NRR, ranging from -1.24 V to -0.21 V.
• Electronic properties of active Ti atoms were modulated by surface termination and non-metallic atoms.
• A descriptor based on the free energy change of *NNH₂ (*NNH₂ ΔG) was proposed for predicting NRR performance.
• Work function was identified as a key factor tunable by surface modification.

Conclusions:

• Surface modification of defective MXenes profoundly impacts catalytic activity for NRR.
• The study provides a rational approach for designing efficient electrocatalysts for ammonia production.
• Understanding the interplay between surface termination, electronic structure, and catalytic performance is crucial.