Stabilizing Silver Single-Atom Site via A Pore-Confined Triphenylphosphine for CO₂ Conversion With High...

Area of Science:

• Heterogeneous Catalysis
• Materials Science
• Green Chemistry

Background:

• Dispersion and anti-aggregation of single-atom sites are critical challenges in heterogeneous catalysis.
• Metal-organic frameworks (MOFs) offer promising platforms for catalyst design due to their tunable structures.

Purpose of the Study:

• To develop a stable and efficient single-atom catalyst using a dual-confinement strategy.
• To investigate the catalytic activity and selectivity of the new catalyst for CO2 conversion.
• To understand the role of the confinement strategy in preventing single-atom aggregation.

Main Methods:

• Construction of a MOF-based catalyst (MEC-88) by confining triphenylphosphine (PPh3) within MOF-808 pores.
• Anchoring silver single-atom sites onto the PPh3-modified MOF.
• Evaluation of catalytic performance for the carboxylative cyclization of CO2 with propargylamines under aqueous conditions.
• Mechanistic studies using computational and experimental approaches.

Main Results:

• MEC-88 demonstrated exceptional activity (turnover frequency up to 1051.3 h-1) and substrate selectivity.
• The PPh3 ligand effectively anchored silver atoms, preventing aggregation and ensuring catalyst recyclability.
• Synergistic activation of substrates and CO2 by the PPh3-coordinated silver site and Zr6O8 cluster was observed.

Conclusions:

• The molecule-enhanced confinement approach successfully created a stable and highly active single-atom catalyst.
• This strategy offers a pathway for designing catalysts with controllable substrate specificity for CO2 utilization.
• The findings advance the field of single-atom catalysis and sustainable chemical synthesis.