Flexible CO₂ Sensor Architecture with Selective Nitrogen Functionalities by One‐Step Laser‐Induced Conversion of Versatile Organic Ink

Abstract

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

Laser‐Carbonization – A Powerful Tool for Micro‐Fabrication of Patterned Electronic Carbons

“…Differences appear mainly in the oxygen content on the surface, which is significantly higher in the presence of oxygen. [ 183 ] Subsequently, the surface polarity is much higher which was confirmed by contact angle measurements. [ 10,217 ] In general, the presence of O 2 promotes the combustion reaction at high reaction temperatures.…”

“…Moreover, additives or reactants are used to implement heterostructures (nanoparticles) into the LP‐C, by which electronic heterojunctions are incorporated. [ 183 ]…”

Laser-Patterned Porous Carbon/ZnO Nanostructure Composites for Selective Room-Temperature Sensing of Volatile Organic Compounds

“…35 Remaining carbon is rearranged and recrystallized and thus forms highly graphitized domains (Figure 3c−e). 48 At temperatures above the boiling point of zinc (907 °C), liquid zinc evaporates. The high degree of graphitization and the absence of ZnO nanoparticles in the upper layers of the LP-C/Zn film indicate that the reaction temperatures are significantly higher than 907 °C.…”

“…When the laser-induced temperature reaches ∼670 °C, ZnO is reduced to Zn according to the carbothermic reduction mechanism, during which carbon is oxidized to gaseous monoxide carbon (CO (g) ) . Remaining carbon is rearranged and recrystallized and thus forms highly graphitized domains (Figure c–e) . At temperatures above the boiling point of zinc (907 °C), liquid zinc evaporates.…”

Modulating between 2e− and 4e− pathways in the oxygen reduction reaction with laser-synthesized iron oxide-grafted nitrogen-doped carbon

“…However, by the degree of graphitization a reaction temperature gradient of <500 °C and >1500 °C between the lower and the upper layer of the LP-NC film is assumed. 37 The difference between the two routes lies in the prearrangement and the nature of the iron precursors in the primary inks.…”