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Abstract

Nitrogen-doped carbons (NC) are a class of sustainable materials for selective CO₂ adsorption. We introduce a versatile concept to fabricate flexible NC-based sensor architectures for room-temperature sensing of CO₂ in a one-step laser conversion of primary coatings cast from abundant precursors. By the unidirectional energy impact in conjunction with depth-dependent attenuation of the laser beam, a layered sensor heterostructure with porous transducer and active sensor layer is formed. Comprehensive microscopic and spectroscopic cross-sectional analyses confirm the preservation of a high content of imidazolic nitrogen in the sensor. The performance was optimized in terms of material morphology, chemical composition, and surface chemistry to achieve a linear relative resistive response of up to ∆R/R₀ = -14.3% (10% of CO₂). Thermodynamic analysis yields Δ_adsH values of -35.6 kJ·mol^-1 and 34.1 kJ·mol^-1 for H₂O and CO₂, respectively. The sensor is operable even in humid environments (e.g., ∆R/R_0,RH=80% = 0.53%) and shows good performance upon strong mechanical deformation.