Abstract

Biomass, as a source of lignocellulose, can be valorized into carbon micro/nanofibers for adsorbing greenhouse gas (GHGs) emissions, especially CO2. This article is derived from systematic evidence evaluation of published studies, presenting new, innovative, and systemic approaches to lignocellulose-based carbon micro/nanofiber studies. The review covers a general overview of carbon micro/nanofiber studies, mapping chronicles of the studies, carbon micro/nanofiber types for CO2 uptake, carbon micro/nanofibers fabrication and characterization, obtained carbonaceous material activation and performances, regulatory frameworks, and sustainability. The published studies show that carbon fiber has been researched for GHG emissions adsorption since the 1950s, with an increasing trend of publication numbers. The trend of studies has commenced from activated carbon to nanocarbonaceous materials and their composites. The excellent performance of both micro/nano-sized carbon provides promising opportunities for absorbing CO2 and other GHGs, such as NO2 and CH4, facilitating decarbonization. Several types of carbonaceous activation processes and modifications were utilized to enhance the performances of the resultant biochars, especially in surface materials, CO2 adsorption capacity, and CO2 selectivity. Proposed mechanisms for the absorption of CO2 by activated carbonaceous materials through physisorption and chemisorption were also observed. To date, regulatory frameworks on the use of activated carbon for CO2 capture are still rarely found, but biochar has been mainstreamed and regulated internationally for CO2 removal. Other regulations have been enacted but have not yet internationally harmonized, mostly focusing on the terminology of carbon nanotubes, characterization, general applications, labelling, packaging, transportation, and the effects of toxicity on health. This study also proposed the sustainability aspects and performance indicators that can be used for circular economy application with an ultimate goal of climate change mitigation through GHG reduction. Besides the regulatory framework, elements of the business model and sustainability were proposed in the circular economy framework of the fibers. By scoping carbon micro/nanofibers studies, it is shown with obvious evidence that carbon micro/nanofibers and their composites have the potential for CO2 adsorption and removal, leading to the acceleration of the decarbonization process that is in line with the Paris Agreement, especially in applying innovative CO2 capture, storage, and utilization (CCSU) technologies.