Green Synthesis of 3D Chemically Functionalized Graphene Hydrogel for High-Performance NH₃ and NO₂ Detection at Room Temperature

Abstract

To address the low gas sensitivity of pristine graphene (Gr), chemical modification of Gr has been proved as a promising route. However, the existing chemical functionalization method imposes the utilization of toxic chemicals, increasing the safety risk. Herein, vitamin C (VC)-modified reduced graphene hydrogel (V-RGOH) is synthesized via a green and facile self-assembly process with the assistance of biocompatible VC molecules for high-performance NH3 and NO2 detection. The three-dimensional (3D) structured V-RGOH is highly sensitive to low-concentration NH3 and NO2 at room temperature. In comparison with those of the unmodified RGOH, the V-RGOH gas sensors display an order of magnitude higher sensitivity and much lower limit of detection, resulting from the enhanced interaction between VC and analytes. NH3 and NO2 with extremely low concentrations of 500 and 100 ppb are detected experimentally. Notably, imbedded microheaters are exploited to explore the temperature-dependent gas sensing properties, revealing the negative and positive impacts of temperature on the sensitivity and recovery speed, respectively. Notably, the V-RGOH sensor exhibits remarkable selectivity and linearity and a wide detection range. This work reveals the remarkable effects of chemical modification with biodegradable molecules and 3D structure design on improving the gas sensing performance of the Gr material.

Self‐Calibrated, Sensitive, and Flexible Temperature Sensor Based on 3D Chemically Modified Graphene Hydrogel

“…[ 5 ] Especially for the 3D porous graphene, the charge carriers could hop between RGO sheet junctions. [ 31,38 ] It is proved that the lower carrier density brings about the higher thermal sensitivity for both graphene and other materials, such as Si nanowire. [ 10,55 ] Both the ‐SO 3 H and oxygenated groups decrease the carrier density and conductivity of S‐RGOH (Figures S5a and S6a, Supporting Information), leading to a higher sensitivity.…”

“…Note that two‐dimensional (2D) reduced graphene oxide (RGO) sheets can be self‐ assembled into three‐dimensional (3D) graphene hydrogels with a porous structure, high specific surface area and unique properties via a one‐step, facile hydrothermal approach without the requirement of external templates. [ 30–33 ] Recently, 3D structured and porous graphene has been extensively investigated and employed for high‐performance chemical sensing, energy storage and electrochemical applications, etc., due to their increased surface to volume ratio, abundant reactive sites, and enhanced charge/mass/thermal transfer compared with the 2D counterpart. [ 34–37 ] However, most of the graphene‐based temperature sensors focus on 2D graphene/RGO sheets and their composites, leaving the thermal sensing properties of 3D graphene unexplored.…”

Microwave-Assisted Rapid Synthesis of Reduced Graphene Oxide-Based Gum Tragacanth Hydrogel Nanocomposite for Heavy Metal Ions Adsorption

“…On applying Bragg's law, the calculated interlayer spacing of RGO was 0.367 nm. Another peak of RGO at 2θ = 43.6 • corresponded to the fingermark of graphite indicating the regeneration of graphitic onto RGO [34]. According to Scherrer's formula the calculated particle size of RGO at 2θ = 24.3 • was 0.894 nm.…”

Exploring the Silent Aspect of Carbon Nanopores

“…Nevertheless, the physical interactions and retention of gases with strong adsorption forces affected the conductivity of the film by contributing to the overall effect of an adsorbed condense phase electronic properties and also by specific electronic interactions with the pore walls. Various research reports have been recently published stressing the importance of the pore system in carbon-based materials for sensing properties [72][73][74].…”