Facile synthesis of SnO2-Fe2O3 core-shell nanostructures and their 2-methoxyethanol gas sensing characteristics

Numerous health hazards arising from the exposure of 2-methoxyethanol (2-ME) and lack of best performing 2-ME sensors pushed us to develop a sensor that can sense 2-ME gas very efficiently. SnO2-Fe2O3 core-shell nanoparticles (CSNPs) were prepared using two step process, in first step core was prepared by co-precipitation method and in the second step the shell was developed by simple sol-gel method. Structural, morphological and compositional studies were carried out systematically and confirmed the perfect formation of core-shell structures with sizes around 18 nm. Further, it revealed that 4 nm Fe2O3 shell was uniformly coated on SnO2 core which demonstrated the formation of heterostructures. Gas sensing properties of fabricated sensors (pure SnO2, Fe2O3 nanoparticles (NPs) and SnO2-Fe2O3) were investigated at room temperature towards various toxic gases. SnO2-Fe2O3 gas sensor has shown tremendous response (∼2080) towards 100 ppm 2-ME gas at room temperature which was much higher than pure NPs based sensors. Response and recovery times of SnO2-Fe2O3 sensor also measured and found to be 43 s and 23 s respectively. Long term stability of the SnO2-Fe2O3 sensor during the first 30 days of its fabrication was tested. Enhanced sensing performance of SnO2-Fe2O3 sensor was attributed to the n-n heterostructures formed between SnO2 core and Fe2O3 shell and porous outer surface of the sensor. All the results suggested that the SnO2-Fe2O3 sensor has great potential for applications in designing practical 2-ME gas sensors.