Stepwise emergence of CO gas sensing response and selectivity on SnO₂ using C supports and PtO_x decoration

Room temperature gas sensing is crucial for practical devices used in indoor environments. Among various materials, metal oxides are commonly used for gas sensing, but their strong insulating properties limit their effectiveness at room temperature. To address this issue, many studies have explored diverse methods such as nanoparticle decoration or conductive support, etc. Here, we report the emergence of gas-sensing functionality at room temperature with improved CO gas selectivity on SnO₂ nanoparticles through sequential steps by using amorphous carbon (a-C) support and PtO_x decoration. The SnO₂ decorated on amorphous carbon shows enhanced gas adsorption compared to inactive gas sensing on SnO₂ decorated carbon support. The higher V_o site of SnO₂ on a-C induces gas adsorption sites, which are related to the higher sp² bonding caused by the large density of C defects. The ambiguous gas selectivity of SnO₂/a-C is tailored by PtO_x decoration, which exhibits six values of sensing responses (R_g/R_a or R_a/R_g) under CO gas at room temperature with higher selectivity. Compared to PtO_x/a-C, which shows no response, the enhanced CO gas sensing functionality is attributed to the CO adsorption site on PtO_x-decorated SnO₂ particles. This report not only demonstrates the applicability of CO gas sensing at room temperature but also suggests a strategy for using SnO₂ and carbon compositions in gas sensing devices.