Electrostatically Guided Covalent Architectures for Stable Hydrogen Evolution at Ampere-Level Current Densities in...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Acidic water electrolysis faces challenges with catalyst degradation at high current densities due to bubble evolution.
• Concentration polarization and mechanical stress compromise catalyst stability in acidic environments.

Purpose of the Study:

• To develop a robust electrocatalyst for stable, high-current-density acidic water electrolysis.
• To investigate a novel catalyst structure combining molybdenum carbide nanoclusters with nitrogen-doped carbon nanotubes.

Main Methods:

• Synthesized Mo2C nanoclusters anchored onto nitrogen-doped carbon nanotubes (NCNTs) using covalent bonds via electrostatically guided self-assembly and carbonization.
• Tested catalyst performance in 0.5 m H2SO4, measuring overpotentials at high current densities (500-1000 mA cm-2).
• Evaluated long-term stability at 865 mA cm-2 and performance in a proton exchange membrane water electrolyzer at 1000 mA cm-2.

Main Results:

• The Mo2C/NCNTs catalyst exhibited low overpotentials: 256 mV at 500 mA cm-2 and 396 mV at 1000 mA cm-2.
• Achieved stable operation at 865 mA cm-2 for over 240 hours in acidic media.
• Demonstrated sustained overall water splitting at 1000 mA cm-2 with a cell voltage of 2.03 V for over 150 hours in a PEM water electrolyzer.

Conclusions:

• The hierarchical covalent design enhances conductivity, durability, and bubble management for electrocatalysts.
• This scalable strategy enables next-generation electrocatalysts for efficient, stable, ampere-level operation in acidic water electrolysis.