The arch-shaped single electrode based triboelectric nanogenerator (TENG) is fabricated using thin film of reduced graphene oxide nanoribbons (rGONRs) with polyvinylidene fluoride (PVDF) polymer used as binder to effectively convert mechanical energy into electrical energy. The incorporation of rGONRs in PVDF polymer enhances average surface roughness of rGONRs/PVDF thin film. With the combination of the enhancement of average roughness and production of functional groups, which indicate improve charge storage capacity of prepared film. Furthermore, the redox peaks obtained through cyclic voltammetry were identified more in rGONRs/PVDF composite in comparison to pristine rGONRs to confirm charge transfer capability of film. Herein, the output performance was discussed experimentally as well as theoretically, maximum voltage was obtained to be 0.35 V. The newly designed TENG to harvest mechanical energy and opens up many new avenues of research in the energy harvesting applications.

Nowadays, humidity sensors have become essential in numerous applications. However, there are several problems while using them for humidity detection, such as low sensitivity, delayed response and recovery times, less stability, and narrow humidity detection ranges. Here, we demonstrate for the first time a highly sensitive chemiresistive sensor for low-level humidity detection in ambient atmosphere by introducing graphene oxide (GO) and doped GO (Li-doped GO and B-doped GO) as a thin film in a facile manner. The sensitivity, repeatability, and stability studies show that thin film-based fabricated humidity sensors are unprecedently efficient in the detection of different percentages of humidity from 11 to 97% at room temperature. The incorporation of doping into GO induces a dramatic change in the sensing behavior of the base film (undoped GO). This allows the sensor to be used in a variety of applications such as humidity sensing, which we validate through our experiment with a “cheap and readily available” recognition system.

In this work, a selective chemiresistive gas sensor for carbon dioxide gas detection at room temperature (∼25 °C) was successfully fabricated, where ruthenium-decorated tungsten disulfide (Ru@WS2) quantum dots (QDs) have been used as the sensing material. A mixed solvent of lithium hydroxide (LiOH · H2O) and N-methyl-2-pyrrolidone (NMP) was used to obtain the Ru-decorated WS2 QDs from the exfoliated WS2 nanoflakes. Then, the prepared WS2 QDs and Ru@WS2 QDs were confirmed using different material characterization techniques. The gas sensors were prepared by spraying the WS2 QDs and Ru@WS2 QDs on gold interdigitated electrodes (IDE), and were then exposed to various concentrations of CO2 gas in dry air conditions. Also, the effect of humidity on both sensors in 5000 ppm CO2 gas has been studied. The Ru@WS2 QD based sensor showed superior sensitivity and good selectivity to CO2 gas in comparison with isopropanol, acetone, ethanol, methanol and benzene at room temperature than the WS2 QD. The sensor showed an increase in resistance when exposed to CO2 gas ranging from 500 to 5000 ppm, indicating p-type characteristics. The Ru@WS2 QD shows less effects at different humid conditions compared to WS2 QD as a CO2 gas sensor.

In this work, a selective chemi‐resistive gas sensor of molybdenum diselenide/graphene (MoSe2/G) nanoflakes (NF) that detects ammonia (NH3) and nitrogen dioxide (NO2) gas at room temperature is successfully fabricated. The MoSe2/G NF based sensor shows good sensitivity (2.476 ppm−1) and selectivity to NO2 in comparison with some VOCs and toxic gases than MoSe2 NF (2.275 ppm−1). But in case of NH3 gas, it shows a drastic increase in sensitivity of MoSe2/G NF (9.115 ppm−1) than MoSe2 NF (2.466 ppm−1). The MoSe2/G NF shows a low detection limit (11 ppb for NH3 and 41 ppb for NO2), an outstanding repeatability, and a reliable long‐term device durability (more than eight weeks) significantly. The reason of the significant improvement in gas sensing performance can be attributed mainly due to the addition of graphene in MoSe2 NF which in turns increases the surface‐to‐volume ratio. It encourages the adsorption of gas molecules on the surface of the material, thereby facilitating the charge transfer process. The superior performance of this gas sensor makes MoSe2/G NF a potential candidate for NO2 and NH3 gas detection at room temperature. Due to the presence of graphene, MoSe2 NF becomes less hydrophilic which shows very less effect of humidity effect.

No abstract