Applications and prospects of nanomaterials for enhanced geological CO2 sequestration: A review

The increasing atmospheric CO2 levels and their environmental impacts have made geological sequestration a critical strategy for carbon mitigation. This review examines the revolutionary role of nanomaterials in enhancing CO2 geological storage efficiency and security. We analyze the fundamental mechanisms of CO2 geological sequestration, including structural, residual, solubility, and mineral trapping, while highlighting the unique properties of various nanomaterials that address key challenges in storage operations. The review focuses on nanosilica, nanoalumina, and other engineered nanoparticles' applications in wellbore cement enhancement, formation modification, and CO2 capture processes. These materials demonstrate remarkable capabilities in improving cement mechanical properties, reducing permeability, enhancing CO2 resistance, modifying formation wettability, and optimizing trapping mechanisms. Despite promising results, challenges persist regarding nanoparticle dispersion, cost-effectiveness, scale-up implementation, and environmental implications. This review also discusses emerging trends in smart nanomaterial development and identifies critical research gaps in understanding long-term behavior under storage conditions.