Fe3O4 nanoparticles modified WS2 microflakes for ammonia detection at room temperature

The WS 2 microflakes heterostructured with n-type Fe 3 O 4 have been explored herein for chemiresistive-type NH 3 sensors at room temperature . The microjunctions formed between the two heteromaterials WS 2 and Fe 3 O 4 effectively modulate the response of the sensor to ammonia. The Fe 3 O 4 /WS 2 heterostructured sensor found a three times higher response relative to the single WS 2 based one. The optimized concentration of Fe 3 O 4 in the heterostructure sample is 0.2 at%. The sensor also indicates an excellent selectivity to several volatile organic compounds (VOCs) such as formaldehyde, toluene, methanol, ethanol, and acetone . The sensing mechanism of the sensor to NH 3 at room temperature were examined using in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). It reveals that the redox reactions of NH 3 on Fe 3 O 4 /WS 2 were more prominent compared to the WS 2 alone. The enhanced sensitivity of the Fe 3 O 4 /WS 2 based sensor could thus be attributed to the joint effects of both electronic and chemical sensitizations induced by the Fe 3 O 4 /WS 2 heterostructures.