Enhanced xylene sensing of MoO3 via SrMoO4 heterojunction engineering

Volatile organic compounds (VOCs), particularly xylene, are hazardous air pollutants that pose significant health risks due to their toxicity and widespread occurrence in indoor and industrial environments. In this work, we report a xylene gas sensor based on MoO 3 decorated with SrMoO 4 nanoparticles, designed to achieve enhanced sensing performance through heterojunction engineering. The SrMoO 4 /MoO 3 composites were synthesized via a facile solvothermal route, enabling uniform dispersion of SrMoO 4 on the MoO 3 surface. Among the fabricated samples, the optimized SrMoO 4 /MoO 3 sensor exhibited a high response of 29.2 toward 20 ppm xylene at 200°C, with rapid response/recovery times (5/7   s), surpassing that of pristine MoO 3 by 15.4 times. Moreover, the sensor also showed excellent selectivity toward xylene over other interfering gases such as acetone, trimethylamine, formaldehyde, and ammonia. The superior sensing behavior is attributed to the combined effects of n-n heterojunction formation, reduced crystallite size with lattice strain, increased surface area and pore volume, band gap narrowing, and enhanced chemisorbed oxygen and oxygen vacancy concentration. This study proposes an effective route for constructing advanced xylene sensor through rational heterojunction engineering.