Climate change is a major crisis that affects human lives with a detrimental impact on decades of progress in global health. As a major contributor to the climate change, global warming that is mainly attributed to CO2 emission demands an effective mitigation strategy. Under such a circumstance, nanomaterials with high surface-area-to-volume ratios are promising in CO2 capture. As a relatively new family member of carbon-based nanomaterials, carbon dots (CDs) that possess small particle sizes (1-10 nm) but high surface-area-to-volume ratios and abundant surface functional groups such as amine and hydroxyl groups are particularly favored for this application. In this study, four types of CDs, namely carbon nitride dots (CNDs), gel-like CDs (G-CDs), pentaethylenehexamine (PEHA)-derived CDs (P-CDs), and yellow-emission CDs (Y-CDs), were synthesized by following their respective well-established protocols.