PNNL

Abstract

Carbonic anhydrase (CA) mimics have received significant attention due to their promising applications in the enhanced hydration and sequestration of CO2. Despite advances made in designing CA mimics using sequence-defined macromolecules, this area is underexplored with limited success. Herein, we report the assembly of sequence-defined peptoids into crystalline nanomaterials with controlled microenvironment of active sites as CA mimics for promoted hydration and sequestration of CO2. By incorporating specific ligands into self-assembling peptoids and coordinating these ligands with metal cations, we synthesized a variety of crystalline nanosheets and nanotubes and demonstrated their high efficiency as CA mimics for catalytic hydrolysis of p-nitrophenyl acetate (p-NPA). We demonstrated that tuning of morphology, crystallinity, and surface and ligand chemistries of these CA mimics is crucial for their catalytic activities. Among them, Zn2+-containing crystalline nanotubes with three imidazolyl side chain groups exhibited the highest catalytic efficiency comparable to natural bovine CA. Molecular dynamics simulations revealed the critical roles of peptoid-Zn2+ binding energy and the active stie local microenvironment on the catalytic performance of these CA mimics. CO2 precipitation results showed that these CA mimics remarkably promote the hydration and sequestration of CO2 while remaining high thermal and chemical stability. Nuclear magnetic resonance (NMR) results further confirmed the catalytic feature of these CA mimics and demonstrated their promoted CO2 hydration and deprotonation of HCO3- into CO32- accompanied by the change of CaCO3 formation pathways, thus accelerating the mineralization of CO2 into stable calcite solids. This study offers essential guidance for the future design of high-performance CA-mimics suitable for applications in CO2 capture and sequestration.