Robust Gold Nanocluster Protected with Amidinates for Electrocatalytic CO₂ Reduction

Area of Science:

• Nanotechnology
• Catalysis
• Materials Science

Background:

• Gold nanoclusters are promising catalysts but often lack stability.
• Developing robust and efficient catalysts for CO2 electroreduction is crucial for sustainable energy solutions.

Purpose of the Study:

• To synthesize and characterize the first all-amidinate-protected gold nanocluster, Au28.
• To investigate the catalytic performance of Au28 for CO2 electroreduction.
• To elucidate the structural and electronic factors contributing to its stability.

Main Methods:

• Synthesis of the gold nanocluster [Au28(Ph-form)12](OTf)2.
• Single crystal X-ray diffraction for structural determination.
• Electrochemical testing for CO2 reduction catalysis.
• Density Functional Theory (DFT) computations for electronic structure analysis.

Main Results:

• Au28 exhibits a stable tetrahedral core-shell structure (Au4@Au24) protected by 12 bridging formamidinate ligands.
• The nanocluster remains intact in solution at 80°C for 6 days.
• Achieved 96.5% Faradaic efficiency for CO2 electroreduction at -0.57 V and a TOF of 1731 h⁻¹ at -0.87 V.
• Supported Au28/CNTs catalyst showed stable potentials for 40 hours with >91% FE(CO).

Conclusions:

• The all-amidinate protection confers exceptional stability to the Au28 nanocluster.
• Au28 is a highly efficient and stable catalyst for CO2 electroreduction.
• Strong gold-ligand binding and geometric shell closure (1S²1P⁶2S²1D⁴ electron configuration) explain the observed stability.