Fabrication of enhanced sensitive and selective porous indium oxide nanocube sensor for NO₂ detection

Porous nanoarchitectures of metal oxide semiconductors (MOS) are promising advanced materials due to their relatively higher surface area, more active sites and are beneficial for variety of applications. Herein, we report a simple method for making porous Indium oxide nanocubes (PINC) using a novel surfactant based biogenic hydrothermal method followed by a nanoscale Kirkendall effect. The nucleation and growth of PINCs were optimized by controlling amount of Cetyl Trimethylammonium Bromide (CTAB), which helps to control the size of nanocubes. The formation of porosity on the nanocubes through the nanoscale Kirkendall effect was proposed. Furthermore, the PINC based films were employed to fabricate solid-state chemiresistive gas sensor and sensing properties were studied. The PINC based film sensor was found to respond towards Carbon dioxide (CO₂), Acetone ((CH₃)₂CO), Ammonia (NH₃), and Nitrogen dioxide (NO₂) gases. However, It exhibited highest gas response to NO₂ gas (response S = 3450) with a shorter response (Rs = 14s) and recovery time (Rc = 115s) at 100 °C operating temperature. Besides, the sensing properties such as linearity, selectivity and real-time sensing analysis were also studied systematically. Herein, we demonstrated the effect of porosity and size of nanocubes on the sensing properties of PINC based sensor device.