Greenery-inspired nanoengineering of bamboo-like hierarchical porous nanotubes with spatially organized bifunctionalities for synergistic photothermal catalytic CO2 fixation

Abstract

The fixation of CO₂ and epoxides into cyclic carbonates is a promising strategy for the resourceful use of CO₂. However, halogen-based homogeneous co-catalysts are usually required for synergistic catalysis in most heterogeneous catalytic systems, which complicates the process of product separation and purification. Furthermore, CO₂ cycloaddition usually requires heating to drive the reaction, making it a highly energy-consuming catalytic process. Herein, the hyper-cross-linked mesoporous poly(ionic liquid)s and nickel-based bamboo-like N-doped carbon nanotubes are spatially organized to construct a synergistic photothermal catalytic system for CO₂ cycloaddition (denoted as Ni-BNCNTs@HMPs-NH₂). The integrated bifunctional catalyst Ni-BNCNTs@HMPs-NH₂ exhibits superior activity and stability for the conversion of CO₂ to cyclic carbonates under mild and co-catalyst/solvent-free conditions. Specifically, when the light intensity is 0.4 W cm⁻², the reaction temperature can reach 74.2 °C, the yield is 99%, and there is no significant activity loss after 10 cycles of catalysis. Various characterizations illustrate that atomically dispersed Ni–N–C sites and imidazolium-based poly(ionic liquid)s in the Ni-BNCNTs@HMPs-NH₂ can act as Lewis acid sites and nucleophiles for synergistic catalytic CO₂ cycloaddition, respectively. In addition, under light irradiation, bamboo-like carbon nanotubes and plasmonic Ni nanoparticles facilitate the photothermal conversion, and semiconductor Ni–N–C generates photogenerated electrons as well as accelerates the rate-limiting step of the CO₂ cycloaddition. This work provides insights into low-energy photothermal-driven catalytic CO₂ conversion.