Monitoring CO2 is imperative to understand its origin and impact. Both, the global climate crisis and the current COVID-19 pandemic have shifted attention and created awareness of the need in comprehensive CO2 monitoring on local and global scales. To fight global warming, a deeper awareness of the public for the impact of greenhouse gases like CO2 may be required. In industrial and work environments, high concentrations of CO2 (in)directly pose health risks due to acidosis or the enrichment of undesired species like viruses, or may cause performance loss even during office work. Capable smart mobile devices and flexible wearables to collect exhaled breath may support decentralized healthcare as well as professional and amateur sport. Handheld or stationary infrared-absorption sensors represent the state-of-the-art device technology but exhibit limitations regarding versatility, compactness and integrability. Integrated micro-sensors, with a superior property portfolio including small size, flexibility, and low cost would facilitate comprehensive spatial and temporal analyses of CO2 in a wide range of applications. Thus, the development of simple miniaturized sensors with rapid response for a wide range of CO2 concentrations has attracted attention among materials scientists. Device concepts are typically based on synthetically functionalized or hybridized (with metals or metal oxides) carbon nanomaterials (CNM) to provide specific active sites on their surface or to tune their electronic properties, respectively. However, relatively high costs, associated with the sophisticated materials and fabrication processes, are still a challenge for commercialization. A promising inexpensive alternative are tailored nitrogen-doped carbons (NCs). Such NCs, obtained from pyrolysis, are a class of materials, which has been proposed for selective CO2 capture or conversion as they intrinsically provide selective binding sites for CO2. In particular, polypyrrole or imidazole-based NCs demonstrate a remarkable CO2 sorption capacity as well as excellent environmental stability and electrical conductivity. Like CNMs, those particulate NCs require additional processing steps to generate complex sensor architectures.