Interstitial Doping in Ultrafine Nanocrystals for Efficient and Durable Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Transition metal catalysts are crucial for efficient and stable overall water splitting (OWS).
• Reducing green hydrogen production costs requires advanced catalysts.
• Developing bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential.

Purpose of the Study:

• To fabricate highly efficient and stable heterojunction coatings for overall water splitting (OWS).
• To explore a deposition-diffusion strategy for synthesizing transition metal interstitial solid solution (TMISS) nanocrystals.
• To enhance the catalytic activity and stability of electrocatalysts through electronic regulation.

Main Methods:

• Fabrication of heterojunction coatings using a sputtering deposition technology and a deposition-diffusion strategy.
• Synthesis of ultrafine FeCoNi-C-N transition metal interstitial solid solution (TMISS) nanocrystals (~1.9 nm) embedded in amorphous nitrided carbon (NC).
• Characterization of the crystalline-amorphous heterojunction interface and electronic properties of the catalyst.

Main Results:

• Uniformly distributed TMISS nanocrystals with maximized atomic utilization were achieved.
• The crystalline-amorphous heterojunction interface demonstrated enhanced electrocatalytic stability.
• Optimized HER and OER activities were observed with low overpotentials (62 mV for HER, 237 mV for OER at 10 mA cm⁻²).
• Excellent OWS performance and long-term stability at high current densities were exhibited.

Conclusions:

• The deposition-diffusion strategy is effective for synthesizing TMISS nanocrystals for bifunctional electrocatalysts.
• Electronic regulation by interstitial C and N atoms significantly improves HER and OER kinetics.
• The developed catalyst shows great promise for cost-effective green hydrogen production via OWS.