Porous and Few-Layer Carbon Nitride Nanosheets via Surface Steam Etching for Enhanced Photodegradation Activity

Abstract

Two-dimensional polymeric carbon nitride (PCN) is a promising semiconductor for photocatalytic redox reactions. Herein, we report a straightforward, scalable, and low-cost production approach to prepare porous and few-layer PCN nanosheets by a steam etching of pristine bulk PCN that was attained from thermal polymerization of guanidinium thiocyanate. By optimization of the supplied amount of water steam, reaction temperature, and time of the steam etching process, the obtained porous and few-layer PCN nanosheets showed drastically increased photocatalytic activity with a hydrogen evolution rate of 0.658 mmol·g–1·h–1, which is 18.3-fold higher than that of pristine bulk PCN (0.036 mmol·g–1·h–1). They also exhibit an outstanding activity and a high stability for the degradation of dyes under visible-light irradiation. Moreover, the proposed steam etching method can also be expanded to other guanidinium precursor salts for the preparation of their corresponding porous and few-layer PCN nanosheets. As such, the steam etching strategy may stand out as an extremely simple method to prepare porous and few-layer PCN nanosheets with remarkably enhanced photocatalytic performances.

Carbon‐Nitride Popcorn—A Novel Catalyst Prepared by Self‐Propagating Combustion of Nitrogen‐Rich Triazenes

“…[64] A common second strategy is relied on "precursors' engineering," in which in addition to the optimization of reaction conditions (temperature profiles and reaction atmospheres), specific precursors are used to achieve the desired C-to-N ratios and morphologies. [65] The third approach is based on PCNs post-formation processing, using various delamination (steam reforming) [66] and further calcination techniques, [67,68] which can lead to formation of foam-like holey ultrathin PCN nano-sheets. [27,69] A particularly interesting application for PCN derived materials that attracted a significant attention in recent years is their utilization in aerospace propulsion systems, as a catalyst for the decomposition of ammonium perchlorate (AP) oxidizer, which is a critical and major component in solid propellants.…”

“…[ 64 ] A common second strategy is relied on “precursors’ engineering,” in which in addition to the optimization of reaction conditions (temperature profiles and reaction atmospheres), specific precursors are used to achieve the desired C‐to‐N ratios and morphologies. [ 65 ] The third approach is based on PCNs post‐formation processing, using various delamination (steam reforming) [ 66 ] and further calcination techniques, [ 67,68 ] which can lead to formation of foam‐like holey ultrathin PCN nano‐sheets. [ 27,69 ]…”

Radial Nano-Heterojunctions Consisting of CdS Nanorods Wrapped by 2D CN:PDI Polymer with Deep HOMO for Photo-Oxidative Water Splitting, Dye Degradation and Alcohol Oxidation

“…Note that the use of CN incorporating PDI units is extremely rare and we are not aware of any reports on exfoliated two-dimensional nanosheets of CN:PDI polymers. The issue of prodigious charge recombination in bulk CN can be solved by its transformation into few-layered sheets which facilitate better charge separation and ensure a shorter distance that photogenerated carriers need to diffuse to react with surface adsorbates and/or electrolyte ions [25]. Hydrogen bonds are responsible for intra-sheet and inter-sheet potential barriers for charge carriers which in turn reduce carrier mobility and increase the probability of recombination losses [26].…”

Enhancing the Fluorescence Activity of Graphitic Carbon Nitride Nanosheets by Eliminating the Active Defect States: Implications for Fluorescent Sensing and Biological Imaging

“…Graphitic carbon nitride (g-CN) is a kind of organic semiconductor that has a typical graphene-like two-dimensional (2D) structure. − Although it was proposed that the 2D framework of the material can be constructed of either triazine or tri- s -triazine, more and more recent evidence indicates that g-CN is mainly composed of tri- s -triazine rather than triazine. − g-CN has been a star material after the discovery of its photocatalytic hydrogen generation activity in 2009 . Besides its excellent photocatalytic activity, − g-CN also has fluorescence (FL) and electrochemiluminescence (ECL) properties that attract the broad attention of many analysts. − In particular, a large number of sensing and imaging systems have been constructed based on the FL properties of various g-CN-based materials. − …”