Tailoring carbon nanomaterial architectures for CO2 capture: structure–property relationships, surface engineering, and future perspectives

Abstract

The rapid rise in atmospheric CO2 concentrations, now exceeding 420 ppm, necessitates the urgent deployment of scalable carbon capture, utilization, and storage (CCUS) technologies to mitigate global warming. This review offers a comprehensive analysis of carbon nanomaterials (CNMs) as a transformative class of adsorbents, providing a sustainable alternative to energy-intensive amine scrubbing. CNMs span all dimensional regimes, ranging from zero-dimensional (0D) fullerenes and carbon dots, through one-dimensional (1D) carbon nanotubes and two-dimensional (2D) graphene, to three-dimensional (3D) hierarchical foams, which exhibit exceptional physicochemical properties, notably high specific surface areas and highly tunable pore architectures. Various surface engineering approaches, including tuning surface chemistry and pore architecture and heteroatom functionalization, have been explored to enhance adsorption capacity and selectivity, as well as enable multiple regeneration cycles. Through structure–property–performance analysis, it has been concluded that ultra-micropores (<0.7 nm) are favorable, which further enhance adsorption capacity at low pressures, the isosteric heat of adsorption (35–50 kJ mol−1), and cycling stability. Furthermore, the surface modification of CNMs through nitrogen doping, amine functionalization, and hybrid composite engineering achieved CO2 adsorption capacities of up to ∼9 mmol g−1 at modest pressures, along with low-temperature regeneration (<100 °C), resulting in energy-efficient performance. This article also outlines ongoing challenges and research frontiers, emphasizing the need to enhance the CO2/N2 selectivity ratio, develop sustainable and scalable synthesis methods, incorporate techno-economic evaluations, and bridge laboratory-scale performance with industrial implementation. Later, a comparative analysis of the modified CNMs with standardized MOFs in terms of capacity is also discussed in detail. This analysis synthesizes current advancements and identifies knowledge gaps, offering a prospective outlook on the development and future trajectories of CNM-based adsorbents in greenhouse gas mitigation and achieving net-zero emission targets.