Reversible Formation of g‐C₃N₄ 3D Hydrogels through Ionic Liquid Activation: Gelation Behavior and Room‐Temperature Gas‐Sensing Properties

Abstract

Many unique properties arise when the 3D stacking of layered materials is disrupted, originating nanostructures. Stabilization, and further reorganization of these individual layers into complex 3D structures, can be essential to allow these properties to persist in macroscopic systems. It is demonstrated that a simple hydrothermal process, assisted by ionic liquids (ILs), can convert bulk g-C 3 N 4 into a stable hydrogel. The gelation occurs through delamination of the layered structure, driven by particular interactions between the IL and the carbon nitride sheets, forming an amphiphilic foam-like network. This study employs spectroscopic and computational tools to unravel the gelation mechanism, and provides a rational approach toward the stabilization of 2D materials in hydrogels. The solution-processable hydrogels can also be used as building blocks of complex devices. Chemiresistive gas sensors employing g-C 3 N 4 3D hydrogels exhibit superior response at room temperature, enabling effective gas sensing under low power conditions.

Oxygen-doped carbon nitride aerogel: A self-supported photocatalyst for solar-to-chemical energy conversion

“…[9] Yan et al fabricated CN hydrogels with the aid of ionic Liquid. [10] Our group also reported the synthesis of polyaniline/CN hydrogel using polyaniline as cross-linking agents. [11] Unfortunately, all the above methods need cross-linking agents to act as supporting materials and self-supported CNA is rarely reported.…”

Carbon Nitride/Reduced Graphene Oxide Film with Enhanced Electron Diffusion Length: An Efficient Photo‐Electrochemical Cell for Hydrogen Generation

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robust, and highly efficient semiconductors; the latter should have good conductivity, be able to transfer charges rapidly at the semiconductor/liquid electrolyte interface, display long-term stability, possess good light-harvesting properties, and have a suitable energy band position for the desired reaction. [45][46][47] Its unique and tunable optical, chemical, and catalytic properties, alongside its low price and remarkably high stability to oxidation, make it a very attractive material for PEC applications. [45][46][47] Its unique and tunable optical, chemical, and catalytic properties, alongside its low price and remarkably high stability to oxidation, make it a very attractive material for PEC applications.

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Recent Developments in Graphitic Carbon Nitride Based Hydrogels as Photocatalysts

“…Internal hydrogen‐bonding or π–π stacking interactions should be higher than that of intra van der Waals interactions of C−N groups within g‐C 3 N 4 aromatic rings to form an interconnected hydrogel. In 2017, Ajayan and co‐workers used an ionic liquid (IL)‐assisted hydrothermal method to exfoliate the g‐C 3 N 4 interlayer by disrupting van der Waals forces, followed by gelation to form a 3D hydrogel structure (Figure a,b) . The interaction of C−H⋅⋅⋅N hydrogen bonds between ILs (C−H group) and N atoms of g‐C 3 N 4 favors the formation of 3D interconnected structures for the gelation process (Figure c).…”

“…g) Proposed photoinitiated polymerization mechanism of a NIPAm/CNNS hydrogel. Reproduced with permission . Copyright 2017, Wiley‐VCH and Royal Society of Chemistry.…”