S-Block Potassium Single-atom Electrocatalyst with K-N₄ Configuration Derived from K⁺ /Polydopamine for Efficient...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysts (SACs) typically utilize transition metals, while s-block elements are considered catalytically inactive due to their electronic structures.
• The exploration of non-traditional elements for catalysis remains a significant challenge in materials science.

Purpose of the Study:

• To report the first s-block potassium single-atom catalyst (K-SAC) with a K-N4 configuration for the oxygen reduction reaction (ORR).
• To investigate the catalytic activity, stability, and mechanism of the K-SAC in alkaline media.
• To demonstrate the potential of s-block elements in designing advanced catalytic materials.

Main Methods:

• Synthesis and characterization of the potassium single-atom catalyst supported on nitrogen-doped carbon (K-N-C).
• Electrochemical evaluation of the K-N-C for oxygen reduction reaction (ORR) in alkaline solution.
• Durability testing in a zinc-air battery.
• Density functional theory (DFT) and crystal orbital Hamilton population (COHP) calculations to elucidate the catalytic mechanism.

Main Results:

• The K-N-C catalyst achieved a high half-wave potential (E1/2) of 0.908 V for ORR with exceptional stability over 10,000 cycles.
• The catalyst exhibited a remarkable power density of 158.1 mW cm⁻² and durability of 420 h in a Zn-air battery.
• DFT and COHP analyses revealed bifunctional active sites (K and C) and highlighted the crucial role of potassium's s-orbitals in ORR intermediate adsorption, differing from transition metals.

Conclusions:

• The development of the s-block K-SAC challenges the conventional view of s-block element inertness in catalysis.
• The K-N-C catalyst shows promising performance for ORR, comparable to state-of-the-art transition metal-based SACs.
• This work provides critical insights for the rational design and mechanistic understanding of novel s-block single-atom catalysts.