Self-Optimized Acidic Ceramic TiB₂ Electrocatalyst: In Situ Electrochemical Exfoliation for Enhanced Hydrogen...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Titanium diboride (TiB2) is a layered transition metal diboride with excellent conductivity and stability, making it a potential electrocatalyst for acidic hydrogen evolution reactions (HER).
• The inherent stacked structure of TiB2 limits active site accessibility and mass transport, leading to high overpotentials during HER.
• Developing efficient electrocatalysts for HER is crucial for renewable energy technologies.

Purpose of the Study:

• To investigate the spontaneous optimization of TiB2 electrocatalysts through in situ electrochemical exfoliation during HER operation.
• To understand the mechanism behind the self-optimization of TiB2 structure and its impact on catalytic activity.
• To establish a new electrochemical activation strategy for layered borides.

Main Methods:

• In situ electrochemical exfoliation of bulk TiB2 during sustained HER operation in acidic media.
• Electrochemical characterization to measure overpotential and active site density.
• Advanced characterization techniques to reveal the self-optimization mechanism, including ion intercalation and structural changes.

Main Results:

• Spontaneous exfoliation of bulk TiB2 into lamellar nanosheets was achieved via potential-driven ion intercalation.
• A significant overpotential reduction of 59% (from 924 to 451 mV @ 10 mA cm-2) was observed.
• The active site density increased by three orders of magnitude (10^3-fold).
• The self-optimization mechanism involves ion-induced interlayer weakening and electronic structure modulation.

Conclusions:

• Electrochemical exfoliation is an effective strategy to transform TiB2 from a precatalyst to a highly active electrocatalyst for HER.
• The dynamic self-optimization of TiB2 enhances its performance by increasing active sites and reducing overpotential.
• This work opens new avenues for designing advanced catalysts based on layered borides for energy applications.