Design and implementation of humidity sensor based on carbon nitride modified with graphene quantum dots

Abstract

Relative humidity (RH) is one of the most important factors that deserve intensive study because of its impact on many aspects of life. In this work humidity sensor based on carbon nitride / graphene quantum dots (g-C3N4/GQDs) nanocomposites have been developed. The structure, morphology and composition properties of the g-C3N4/GQDs were investigated and analyzed by XRD, HR-TEM, FTIR, UV–Vis, Raman, XPS and BET surface area. The average particle size of GQDs was estimated from XRD to be 5 nm and confirmed using HRTEM. The HRTEM images prove that the GQDs are attached to the external surface of the g-C3N4. The measured BET surface area was found to be 216 m2/g, 313 m2/g, and 545 m2/g for GQDs, g-C3N4, and g-C3N4/GQDs respectively. The d-spacing and crystallite size were estimated from XRD and HRTEM and found in a good matching. The humidity sensing behavior of g-C3N4/GQDs was measured in a wide span of humidity from 7% up to 97% RH under different testing frequencies. The obtained results demonstrate good reversibility and fast response/recovery time. The implemented sensor exhibits a great application prospect in humidity alarm devices, automatic diaper alarms, and breath analysis, which have advantages such as strong anti-interference capability, low cost, and easy to use.

3D‐printed green and low‐cost porous g‐C3N4/geopolymer components for the removal of methylene blue from wastewater

“…For 3 wt%C 3 N 4 /GP, GP and g‐C 3 N 4 were stacked together with aggregated layers, and HRTEM analysis allows to identify the presence of lattice features with spacings of 0.336 nm, consistent with the (0 0 2) planes of g‐C 3 N 4 (see Figure 4D). 33–35 …”

“…For 3 wt%C 3 N 4 /GP, GP and g-C 3 N 4 were stacked together with aggregated layers, and HRTEM analysis allows to identify the presence of lattice features with spacings of 0.336 nm, consistent with the (0 0 2) planes of g-C 3 N 4 (see Figure 4D). [33][34][35] In order to study the surface functional groups of the samples, FTIR analyses were carried out (see Figure 5). In pure g-C 3 N 4 , the broad peak in the 2800-3800 cm −1 range can be attributed to the −OH group stretching vibration from adsorbed water and N-H stretching vibration from uncondensed terminal amino group.…”

Ternary nanocomposite comprising MnO2, GQDs, and PANI as a potential structure for humidity sensing applications

“…GQDs were prepared as per the previous report 54 . Citric acid was used as a carbon source to create graphene quantum dots (GQDs).…”

N-doped TiO2/rGO: synthesis, structure, optical characteristics, and humidity sensing applications

“…No diffraction peaks belonging to the GO confirms the complete reduction of GO. The crystallite size was estimated following Scherr 's equation using the most intensive peak [20].…”