Hybrid MoSe$_{2}$/WSe$_{2}$ Nanomaterials: Enhancing Humidity Tolerant Gas Response

Humidity can impair sensor performance, resulting in inaccurate readings and decreased sensitivity, which can undermine the dependability and effectiveness of sensing systems. This can potentially result in flawed data analysis and compromised decision-making. It is important to develop a humidity-stable sensor to ensure accuracy and reliable measurements in humid environments. 2-D materials such as transition-metal dichalcogenides (TMDCs) have high surface-to-volume ratios and moisture-resistant properties, which allow them to exhibit high-sensitivity in humid environments. In this work, molybdenum diselenide (MoSe
$_{2}$
) and its hybrid with Tungsten Diselenide (MoSe
$_{2}$
-WSe
$_{2}$
) were synthesized, characterized, and evaluated for sensitivity to humidity. The response of the sensor was determined from the conductivity measurements of the exfoliated thin films at humidity levels ranging from 40%–80%. The average sensor response for hybrid MoSe
$_{2}$
-WSe
$_{2}$
and pure MoSe
$_{2}$
was 95.5% and 77.58%, respectively, at 40% humidity. At 70% and 80% humidity, the hybrid MoSe
$_{2}$
-WSe
$_{2}$
showed noticeable sensor response (39.75% and 16.95%, respectively), whereas for MoSe
$_{2}$
, the corresponding responses were very poor (0.33% and 0.09%, respectively). The response of the hybrid sensor drops by 16.25% when humidity changes from 40% to 60% indicating reasonably stable behavior while response of MoSe
$_{2}$
continues to degrade sharply as humidity is increased beyond 40%. In addition, the efficacy of the hybrid material was investigated for 200 ppm H
$_{2}$
gas under various humid conditions at room temperature. The results showed that the hybrid MoSe
$_{2}$
-WSe
$_{2}$
exhibited a sensor response of 42.38%. It was noted that when humidity was changed from 40% to 60%, the sensor response reduced by just 3.38%, demonstrating humidity insensitive behavior. This suggests a correlation between the hybrid material's humidity tolerance and its stability when subjected to gas exposure. Thus, this letter highlights that heterostructure nanomaterials are promising candidates for sensing applications in high-humidity environments.