Oxygen-Functionalized Ultrathin Ti₃ C₂ T_x MXene for Enhanced Electrocatalytic Hydrogen Evolution

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Two-dimensional (2D) transition-metal carbides (MXenes) are promising electrocatalysts for the hydrogen evolution reaction (HER).
• MXenes possess metallic conductivity, tunable surface chemistry, and atomic thickness with exposed active sites.
• Existing MXenes often have terminal fluorine groups detrimental to HER, while theoretical studies suggest oxygen functionalization is beneficial.

Purpose of the Study:

• To develop an ultrathin Ti3C2 MXene nanosheet fully functionalized with oxygen for improved HER electrocatalysis.
• To investigate the impact of oxygen functionalization on the HER activity of MXenes.

Main Methods:

• Synthesis of ultrathin Ti3C2 MXene nanosheets.
• Functionalization of the MXene basal plane with oxygen.
• Electrochemical characterization of the oxygen-functionalized Ti3C2 (Ti3C2Ox) for HER activity.

Main Results:

• The synthesized oxygen-functionalized Ti3C2 (Ti3C2Ox) exhibited significantly higher HER activity (190 mV at 10 mA cm−2) compared to Ti3C2Tx (T=F, OH, O).
• The enhanced HER performance is attributed to the highly active oxygen sites on the basal plane of the MXene nanosheets.
• Ultrathin Ti3C2 MXene nanosheets fully functionalized with oxygen demonstrate superior electrocatalytic properties for HER.

Conclusions:

• Complete oxygen functionalization of ultrathin Ti3C2 MXene nanosheets effectively enhances hydrogen evolution reaction (HER) activity.
• The study highlights the critical role of surface functional groups in tuning MXene electrocatalytic performance.
• This work provides a pathway for designing advanced MXene-based electrocatalysts by surface group engineering.