PNNL

Abstract

Carbonate mineralization, the conversion of CO2 into stable, thermodynamically favorable carbonate minerals, offers a promising strategy for permanent and environmentally friendly carbon storage, with minimal risk of long-term leakage risks and minimal monitoring requirements. Drawing inspiration from carbonic anhydrase (CA), a family of zinc-containing metalloenzymes that catalyze the hydration of CO2 to bicarbonate and promote carbonate precipitation, we designed a class of histidine-containing peptoids capable of coordinating with Zn2+ ions to act as CA mimetics for accelerating calcite step growth. In situ atomic force microscopy (AFM) measurements revealed that these peptoids significantly enhance step advancement, with a more pronounced effect observed when combined with Zn2+ ions and under higher calcium-to-carbonate activity ratios, indicating that peptoids facilitate the incorporation of CO32- ions at step edges. Solution NMR and three-dimensional atomic force microscopy (3D AFM) analyses showed that the coordination of peptoids with Zn2+ promote both the deprotonation of HCO3- to CO32- and restructure the interfacial hydration layers of calcite, collectively lowering the activation barrier for step growth. These findings establish a design framework for sequence-defined polymers to regulate carbonate mineralization, offering promising applications in CO2 capture and long-term storage.