Early Transition-Metal-Based Binary Oxide/Nitride for Efficient Electrocatalytic Hydrogen Evolution from Saline Water...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Seawater utilization for hydrogen production via electrocatalytic water splitting reduces freshwater dependency.
• Seawater's composition negatively impacts hydrogen evolution reaction (HER) electrocatalyst stability and activity, particularly at varying pH.
• Developing robust electrocatalysts for HER in saline environments is crucial for sustainable hydrogen generation.

Purpose of the Study:

• To synthesize and evaluate novel binary metallic core-sheath nitride@oxynitride electrocatalysts for HER in saline water.
• To investigate the performance, stability, and underlying mechanisms of these catalysts, especially under near-neutral pH conditions.
• To demonstrate an advancement in earth-abundant electrocatalyst performance for saline water HER.

Main Methods:

• Synthesis of binary metallic core-sheath nitride@oxynitride electrocatalysts [Ni(ETM)]^δ+-[O-N]^δ-, with ETM as V or Cr.
• Electrocatalytic testing of NiVN on nickel foam (NF) in saline water (0.6 M NaCl) for HER.
• Stability testing under constant current densities and comparison with commercial Pt/C electrocatalysts.

Main Results:

• NiVN/NF exhibited a low HER overpotential of 32 mV at -10 mA cm^-2 in 0.6 M NaCl.
• The catalyst demonstrated superior stability, operating at -50 mA cm^-2 for 50 hours and -100 mA cm^-2 for another 50 hours in neutral saline electrolyte.
• Doping with early transition metals (ETM) accelerated H₂O dissociation and suppressed chloride deactivation, with heterointerface synergism observed.

Conclusions:

• The developed NiVN electrocatalyst offers significant advancements in HER performance and stability in neutral saline water.
• Heterointerface synergy between nitride and oxynitride components enhances catalytic activity by facilitating water dissociation and hydrogen ad/desorption.
• Surface charge delocalization principles are key for designing effective HER electrocatalysts in diverse saline environments.