Designing innovative PAni-based adsorbents for CO2 capture via in-situ nitrogen plasma modification for sustainable development

Abstract

Carbon dioxide (CO₂) capture is a critical strategy in the fight against climate change. By implementing this innovative technology, CO₂ emissions from diverse sources will be captured and neutralized, thereby mitigating global warming. For this purpose, novel sorbents were developed in this work by loading TiO₂ and ZnO nanofillers into a polyaniline (PAni) system to form PAni–TiO₂ (PT) and PAni–ZnO (PZ) composites. Following that, in-situ nitrogen (N₂) plasma treatments were applied for 5 min to improve their surface nature and physiochemical properties. The CO₂ capture qualities of modified PT and PZ sorbents were investigated, as well as physical assessments of their microstructure, nuclear magnetic resonance (NMR), morphology, contact angle, roughness, electrical optical, reactivity, stability, and adsorption capability, hardness, softness and electrophilicity properties. Bombardment of high-energy plasma species for 5 min was sufficient to optimize the crystallite size and crystallinity degree in both the PT5 and PZ5 systems. These enhancements may be related to the growth of protonated benzoid rings -NH⁺- as a result of plasma modifications to the structure of PAni and its transformation into emerald salt. In a similar vein, the SEM micrographs, porous topography and hydrophilic nature of the PAni composites varied with respect to the type of nanofillers and plasma level. The plasma treatment provided additional oxygen-containing functional groups as active sites for chemical interactions, including CO₂ via chemisorption or physisorption, facilitating further reduction. Additionally, plasma activities assisted in shifting to a rougher surface (i.e.,Ra = 3.83 µm) as well as optimizing the energy band gap (1.57 eV), which can accommodate more CO₂ molecules, thereby improving the capture efficiency. Moreover, the findings indicate that PZ5 is more desirable for CO₂ adsorption since it possesses a 2.52-fold greater CO₂ adsorption energy (-0.079 a.u) than pristine PZ0. In the future, our work opens up exciting new prospects to achieve desired performance from CO₂ capturing compounds utilizing plasma technology.