Hard-Soft Acid-Base Principle Drives Rational Synthesis of Super-Dense Rare-Earth-Based Diatomic Sites.

Area of Science:

• Catalysis
• Materials Science
• Coordination Chemistry

Background:

• Diatomic catalysts (DACs) offer advantages in atomic economy and synergistic catalysis.
• Challenges include low metal loading, unclear site identification, and lack of design principles.

Purpose of the Study:

• To develop a general synthetic strategy for high-loading DACs.
• To identify diatomic configurations and understand their catalytic mechanisms.
• To improve electrocatalytic nitrate reduction using novel DACs.

Main Methods:

• Utilized the hard-soft acid-base (HSAB) principle for catalyst design.
• Synthesized 14 rare-earth (RE)-based DACs with high metal loadings (12.8-30.7 wt %).
• Employed deep learning for diatomic site recognition and experimental/theoretical analyses for mechanistic studies.

Main Results:

• Achieved record-high metal loadings and atomic site densities (>1.12 × 10^21 sites g^-1).
• Unambiguously identified heterodiatomic configurations with high pairing ratios (60.5%-70.3%).
• Demonstrated up to 2.7-fold enhancement in ammonia yield rates for nitrate reduction.

Conclusions:

• Established a general coordination chemistry-based design principle for DACs.
• The HSAB principle enables the creation of superdense diatomic sites.
• High-loading DACs show superior performance in electrocatalytic applications.