Nickel Single Atoms Embedded in 2D Stacked Polytriazine as an Electrocatalyst for Oxygen Evolution Reaction

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• Synthesizing single-atom catalysts (SACs) with high metal loading and atomic dispersion remains a significant challenge.
• Developing efficient catalysts for the electrochemical oxygen evolution reaction (OER) is crucial for energy conversion technologies.

Purpose of the Study:

• To develop a low-temperature synthesis strategy for stabilizing single metal atoms on a 2D stacked polytriazine framework (g-C3N4) with high metal loading.
• To investigate the structural and electronic properties of the synthesized nickel-based SACs.
• To evaluate the electrocatalytic performance of the Ni-SACs for the oxygen evolution reaction (OER).

Main Methods:

• Microwave-assisted synthesis at 140 °C for 30 min to produce Ni-based SACs embedded in 2D stacked polytriazine.
• Characterization using X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and X-ray Absorption Spectroscopy (XAS).
• Density Functional Theory (DFT) calculations and Extended X-ray Absorption Fine Structure (EXAFS) analysis to determine Ni coordination.

Main Results:

• Achieved high Ni metal loading (up to 2.8 wt %) with atomic dispersion on the polytriazine framework.
• Confirmed Ni2+ coordination with four N atoms in-plane and six N atoms between layers, stabilizing the single atoms.
• Demonstrated excellent OER performance with a low overpotential (330 mV at 10 mA cm-2), low Tafel slope (84 mV dec-1), high turnover frequency (0.05 s-1), and stability up to 50 hours.

Conclusions:

• The low-temperature microwave-assisted synthesis effectively produces highly dispersed Ni SACs on stacked polytriazine.
• The strong Ni-N coordination within the framework enhances catalyst stability and electrocatalytic activity for OER.
• This Ni-SAC system offers a promising pathway for efficient and stable electrochemical oxygen evolution.