Graphene‐Like Carbon Nitride Nanosheets for Improved Photocatalytic Activities

Abstract

Abstract“Graphitic” (g)‐C3N4 with a layered structure has the potential of forming graphene‐like nanosheets with unusual physicochemical properties due to weak van der Waals forces between layers. Herein is shown that g‐C3N4 nanosheets with a thickness of around 2 nm can be easily obtained by a simple top‐down strategy, namely, thermal oxidation etching of bulk g‐C3N4 in air. Compared to the bulk g‐C3N4, the highly anisotropic 2D‐nanosheets possess a high specific surface area of 306 m2 g−1, a larger bandgap (by 0.2 eV), improved electron transport ability along the in‐plane direction, and increased lifetime of photoexcited charge carriers because of the quantum confinement effect. As a consequence, the photocatalytic activities of g‐C3N4 nanosheets have been remarkably improved in terms of •OH radical generation and photocatalytic hydrogen evolution.

Reduced-sized monolayer carbon nitride nanosheets for highly improved photoresponse for cell imaging and photocatalysis

“…As shown in Fig. 3b, the FTIR spectra of both GCNN and NMGCN show a sharp peak at 808 cm −1 , five strong peaks at 1240, 1320, 1400, 1460, and 1550 cm −1 , and a board peak ranging from 3000 to 3500 cm −1 , respectively corresponding to the typical breathing vibration of the s-triazine ring, the characteristic stretching modes of CN heterocycles, and stretching of N-H and O-H bonds [26,29,38]. The FTIR result indicates that the NMGCNs retain the basic structure of the GCN.…”

“…Compared with GCNNs (Fig. 3a), the (002) peak at about 27.5°is much weaker and broader, and the (100) peak at 13.2°has disappeared, indicating that the stacking of the conjugated aromatic systems and the in-plane repeat units of GCN are obviously disrupted after the exfoliation [20,26,37]. A Fourier transform infrared (FTIR) spectrum measurement was conducted to verify the chemical structure of the NMGCNs.…”

“…Thus far, GCNNs prepared with various techniques, such as mechanical milling [24,25], chemical oxidation thermal or etching [20,26,27], physical and liquid exfoliation [22,28,29], and electrochemical synthesis [30] usually show wide distributions in both the number of layers and lateral size. In particular, due to many advantages of easy operation, low-cost, environmental benignity, and no reason for interfacial defects, liquid-phase exfoliation, usually in conjunction with ultrasonic treatment has been intensively explored for producing ultrathin GCNNs by delaminating bulk GCN [28,31,32].…”

Ultrathin g-C3N4 Nanosheet-Modified BiOCl Hierarchical Flower-Like Plate Heterostructure with Enhanced Photostability and Photocatalytic Performance

“…From the HRTEM image (Figure 4c), the interplanar lattice of 0.343 nm between adjacent lattice fringes of top surface in BiOCl can be indexed to (011) plane. Consulting previous study [54], the top and bottom surface are determined to be (001) facets. As indicated by HRTEM image (Figure 4d), a heterojunction was formed along the interface between BiOCl nanoplate and poorly crystallized g-C 3 N 4 nanosheet, demonstrating that the two components are in close contact.…”

Direct Exfoliation of g-C3N4 with Addition of NaOH for Enhanced Photocatalytic Cr(Ⅵ) Reduction

“…It's reasonable that monolayered g-C3N4 nanosheets have excellent photocatalytic properties. For example, Wang firstly stirred it with strong acid (37% HCl) for 3 hours, reporting a reversible protonation of carbon nitride [7]; Liu and his colleagues developed a heat treatment to reduce its size [9]. From these results, the treated C3N4 showed much higher photocatalytic activities than the bulk g-C3N4 under visible light irradiation.…”