A novel nanoparticles spilled-over In 2 O 3 microcubes-enabled sustainable chemiresistor for environmental carbon dioxide monitoring.

Achieving sustainable future energy goals includes enhancing renewable energy production, optimizing daily energy consumption using feedback loops and minimizing/monitoring contributions to atmospheric carbon dioxide (CO 2 ). Developing economic next-generation CO 2 sensors enables local monitoring of industrial CO 2 emissions, aiding energy management and climate monitoring. This study elucidates the efficacy of CO 2 chemiresistor based on indium oxide (In 2 O 3 ) micro cubes with spilled-over nanoparticles. The investigation primarily focuses on fabricating and optimising In 2 O 3 -based CO 2 chemiresistors utilizing a hydrothermal technique, creating porous micro cubes essential for enhanced CO 2 monitoring. As revealed by various characterization techniques, the minimum crystallite size was found to be 24.92 nm with optimum porosity and a high surface-to-volume ratio comprising spilled-over nanoparticle morphology. The fabricated chemiresistor demonstrated excellent CO2 sensing efficacy with a maximum response of around 4.1% at room temperature with selectivity, repeatability, and reversible sensing behavior. The sensing mechanism has been revealed, which is supported by theoretical density functional theory evaluations. Notably, the sensing results reveal the capability of In 2 O 3 -based sensors to detect CO 2 at low concentrations as low as ⩽10 ppm, which enables the chemiresistor for practical implementation in diverse sectors to achieve sustainability.