Engineering hot carrier dynamics in Ti₂CO₂ MXene via methane adsorption

Area of Science:

• Materials Science
• Surface Chemistry
• Computational Chemistry

Background:

• Hot carrier (HC) dynamics are vital for light-driven processes like photocatalysis and gas sensing.
• Oxygen-functionalized Ti2CO2 MXene is a promising material for optoelectronic applications.

Purpose of the Study:

• Investigate the impact of methane (CH4) adsorption on the optoelectronic properties of Ti2CO2 MXene.
• Determine how different CH4 adsorption geometries influence optical properties and hot carrier dynamics.

Main Methods:

• Employed first-principles calculations, including density functional theory (DFT) and real-time time-dependent DFT (rt-TDDFT).
• Analyzed energetically favored adsorption sites, orbital hybridization, and transition contribution maps.

Main Results:

• The bridge configuration of CH4 adsorption is energetically favored over the on-top site, showing significant orbital hybridization.
• CH4 adsorption in the bridge site leads to a red-shifted absorption onset and enhanced visible-light absorption.
• Bridge-site CH4 actively participates in photoexcitation, increasing hole generation, while on-top adsorption shows minimal impact.

Conclusions:

• Adsorption geometry critically tunes the optoelectronic properties of Ti2CO2 MXene.
• CH4 adsorption, particularly in the bridge configuration, offers a pathway for designing responsive materials for photocatalysis, gas sensing, and solar energy harvesting.