DFT-Based Functionalization of Graphene with Lithium-Modified Groups for Enhanced Hydrogen Detection: Thermodynamic,...

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Graphene's unique electronic and optical properties make it a candidate for advanced sensor applications.
• Functionalization of graphene can tailor its properties for specific applications, such as gas sensing.
• Oxygen-containing functional groups with lithium offer a pathway to enhance graphene's interaction with hydrogen.

Purpose of the Study:

• To investigate the impact of different oxygen-containing functional groups (COO-Li, CO-Li, O-Li) on graphene's electronic and optical properties.
• To evaluate the thermodynamic feasibility of graphene functionalization and subsequent hydrogen adsorption.
• To assess the potential of these functionalized graphene materials for hydrogen sensing applications.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to determine Gibbs free energy changes (ΔG) for functionalization and hydrogen adsorption.
• Thermodynamic analysis was performed to assess the spontaneity of the processes.
• Electronic structure analysis was conducted to evaluate band gap modulation.
• Fourier-Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy were used to confirm Li-H interactions.

Main Results:

• Functionalization of graphene with COO-Li, CO-Li, and O-Li groups is thermodynamically favorable (ΔG < 0), with COO-Li being the most favorable.
• Hydrogen adsorption on these functionalized graphene surfaces is also spontaneous, with lithium atoms acting as active adsorption sites.
• All functionalized systems exhibit semiconducting behavior, with band gaps tunable by the functional group.
• Spectroscopic analysis confirmed characteristic vibrational modes indicative of Li-H interactions.

Conclusions:

• Lithium-functionalized graphene, especially COO-Li, presents a promising tunable platform for hydrogen detection.
• The favorable thermodynamics, modulated electronic properties, and spectroscopic detectability support its potential in hydrogen sensing.
• The study highlights the importance of functional group choice in optimizing graphene for sensing applications.