A Dual-Channel MoS2-Based Selective Gas Sensor for Volatile Organic Compounds

Significant progress has been made in two-dimensional material-based sensing devices over the past decade. Organic vapor sensors, particularly those using graphene and transition metal dichalcogenides as key components, have demonstrated excellent sensitivity. These sensors are highly active because all the atoms in the ultra-thin layers are exposed to volatile compounds. However, their selectivity needs improvement. We propose a novel gas-sensing device that addresses this challenge. It consists of two side-by-side sensors fabricated from the same active material, few-layer molybdenum disulfide (MoS₂), for detecting volatile organic compounds like alcohol, acetone, and toluene. To create a dual-channel sensor, we introduce a simple step into the conventional 2D material sensor fabrication process. This step involves treating one-half of the few-layer MoS₂ using ultraviolet-ozone (UV-O3) treatment. The responses of pristine few-layer MoS₂ sensors to 3000 ppm of ethanol, acetone, and toluene gases are 18%, 3.5%, and 49%, respectively. The UV-O3-treated few-layer MoS₂-based sensors show responses of 13.4%, 3.1%, and 6.7%, respectively. This dual-channel sensing device demonstrates a 7-fold improvement in selectivity for toluene gas against ethanol and acetone. Our work sheds light on understanding surface processes and interaction mechanisms at the interface between transition metal dichalcogenides and volatile organic compounds, leading to enhanced sensitivity and selectivity.

Highly sensitive and selective rGO based Non-Enzymatic electrochemical sensor for propamocarb fungicide pesticide detection

In this study, reduced graphene oxide (rGO) was prepared using a green ultrasonic microwave assisted method and investigated rGO based non-enzymatic electrochemical sensor for detecting a synthetic fungicide as a propamocarb (PM) pesticide. The rGO-based sensor exhibited rapid response within 1 min, low detection limit of 0.6 μM and wide linear range of (1-5) μM with a high sensitivity of 101.1 μAμM^-1 cm^-2 for PM. Besides this, the sensor detected the propamocarb pesticide on the real cucumber sample with high sensitivity in the concentration range of (1-5) μM within a 1-minute cycle. The sensor is highly selective against propamocarb pesticide. The prepared non-enzymatic electrochemical sensor exhibited high sensitivity, high selectivity, reproducibility, and rapid response.

Hexylsulfanyl-substituted CoPc and GO-CoPc on Ni foam as electroactive material for supercapacitors

For energy storage applications, hexylsulfanyl-substituted CoPc and GO-CoPc electrodes were prepared on Ni foam, and then electrochemical properties of the materials were investigated. The GO-CoPc nanocomposite electrode exhibits 56 mFcm[Formula: see text] at 1.4 mAcm[Formula: see text] current density. The results show that the GO-CoPc nanocomposite electrode is a promising electroactive material for supercapacitors.