Design and Implementation of Humidity Sensor Based on Bioinspired Mesoporous Activated Carbon/BiVO₄ Nanocomposite

Humidity sensors are widely used instruments in environmental and health monitoring applications. Activated carbon is a biocompatible material which have high surface area and hydrophilicity, therefore activated carbon considered as a promising material for humidity sensing applications. In this work, we synthesized activated carbon-bismuth vanadate (AC/BiVO₄) nanocomposite by green-assisted ultrasonication process and studied their humidity sensing properties. The structural, morphological and sensing properties evaluated using XRD, Raman, FT-IR, FE-SEM, EDX and BET spectroscopy analysis. The XRD technique showed that the prepared AC/BiVO₄ nanocomposite has related to monoclinic phase of BiVO₄ and AC. FE-SEM images show irregular shaped BiVO₄ particles deposited on the surface of AC and the EDX spectra confirms the presence of Bi, V and O elements in the prepared nanocomposite without any other impurities. The measured BET surface area was found 143 m²/g which confirm the mesoporous nature of AC/BiVO₄ nanocomposite. In this humidity sensing work, spin-coating method was used to develop sensing device using ITO substrate. The entire humidity sensing work was carried out 5–98% RH at room temperature. The sensitivity factor of the sensor was studied at three different frequencies (10 H, 100 Hz and 1 kHz). It was observed that the AC/BiVO₄ nanocomposite show high sensitivity factor at 100 Hz frequency and estimated response time of 24 s and recovery time of 50 s RH from 5 to 98% RH. Low hysteresis 2.4% was observed along with excellent stability. This work suggests that AC/BiVO₄ nanocomposite is a promising candidate for monitor relative humidity in the air.