Low-Temperature Carbon Dioxide Gas Sensor Based on Yolk−Shell Ceria Nanospheres

Monitoring carbon dioxide (CO$_2$) levels is extremely important in a wide range of applications. Although metal oxide-based chemoresistive sensors have emerged as a promising approach for CO$_2$ detection, the development of efficient CO$_2$ sensors at low temperature remains a challenge. Herein, we report a low-temperature hollow nanostructured CeO$_2$-based sensor for CO$_2$ detection. We monitor the changes in the electrical resistance after CO$_2$ pulses in a relative humidity of 70% and show the high performance of the sensor at 100 °C. The yolk–shell nanospheres have not only 2 times higher sensitivity but also significantly increased stability and reversibility, faster response times, and greater CO$_2$ adsorption capacity than commercial ceria nanoparticles. The improvements in the CO$_2$ sensing performance are attributed to hollow and porous structure of the yolk–shell nanoparticles, allowing for enhanced gas diffusion and high specific surface area. We present an easy strategy to enhance the electrical and sensing properties of metal oxides at a low operating temperature that is desirable for practical applications of CO$_2$ sensors