Interfacial Electron Modulation of AgxCuy@ZIF-8 for Photothermally Catalyzing CO2 Organic Transformations

Abstract

Efficiently converting CO₂ into valuable chemicals under mild conditions is extremely challenging due to its thermodynamic and kinetic stability. The carboxylation/cyclization of alkynes catalyzed by Cu or Ag nanoparticles (NP) is one of the green pathways for CO₂ utilization. However, these reactions are often limited by harsh conditions, as well as the migration, aggregation, and leakage of metal NP during the reaction. Herein, the Ag_xCu_y heterostructure alloy NP are surrounded by a porous metal–organic framework, forming core–shell Ag_xCu_y@ZIF-8 catalysts. Thanks to the light-to-heat capability, these catalysts exhibited excellent catalytic activity in converting various alkynes and CO₂ to alkynyl carboxylic acids and promoting the cyclization reactions of propargyl amines with CO₂ under ambient conditions using blue LED irradiation. The remarkable catalytic activity of Ag₁Cu₁@ZIF-8 is attributed to the optimized electronic states of Ag and Cu NP, as well as the core–shell structure that enhances photothermal effects around the catalytic center. In addition, the ZIF-8 shell not only improves the substrate transport but also inhibits the aggregation, migration, and loss of alloy NP cores during the reaction, contributing to enhanced cycling performance compared to unencapsulated Ag₁Cu₁ NP. The catalytic reaction mechanisms were disclosed by a variety of spectral characterizations, control experiments, and DFT calculations.