Engineering of metal-organic framework-derived semiconductor metal oxides based on Co3O4: In2O3 nanostructures for m-xylene detection

Accurate real-time detection of xylene isomers is a critical platform for advancing occupational safety and public health monitoring systems. This study focuses on a morphology-driven strategy for engineering metal–organic framework-derived Co 3 O 4 /In 2 O 3 (Co: In) heterostructures with tunable Co ratios for the detection of o -, m -, and p -xylenes, as well as other interfering gases. The results showed that the selectivity of the sensors can be realized by tuning the operational temperature. At 75 °C, both Co In and 2Co In showed better p -xylene selectivity. At 100 and 125 °C, 3Co: In was highly selective towards m -xylene. The increased sensing performance originated from the facile engineered heterostructure, allowing improved interfacial synergy between Co 3 O 4 and In 2 O 3 for improved gas adsorption. A higher Co 3+ /Co 2+ ratio, as evidenced by XPS, also promoted stronger adsorption and activation of oxygen molecules (O₂) on the sensor surface. The increased Co content on the 3Co: In surface, which led to more porous plate-like morphology, also contributed to the sensing performance due to increased catalytic activity, and tuneable properties of 3Co: In. The findings offer a promising route for developing next-generation chemiresistive sensors for real-time air-quality monitoring. • Metal-organic framework (MOF)-derived Co 3 O 4 /In 2 O 3 nanostructures were created with varying Co molar ratios. • The Co 3 O 4 /In 2 O 3 (Co:In) sensor was tested against o-, m-, and p-xylenes, benzene, toluene, and acetone. • The 3Co:In sensor displayed a higher response to m-xylene at 125 °C. • The sensor showed a low detection limit and improved selectivity for m-xylene.