Xiaojie She

Exfoliated graphene-like carbon nitride in organic solvents: enhanced photocatalytic activity and highly selective and sensitive sensor for the detection of trace amounts of Cu2+

Due to their unprecedented electronic, surface and optical properties, the atomic-thick graphene-like materials have aroused great interest. Compared with the bulk counterparts, the graphene-like material can not only enhance the internal properties, but also gives rise to new promising properties. Herein, the graphene-like carbon nitride (graphene-like C3N4) was synthesized via liquid exfoliation from the bulk graphitic carbon nitride (g-C3N4) in 1,3-butanediol (1,3-BUT) for the first time. And the graphene-like C3N4 was characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), and X-ray photoelectron spectroscopy (XPS). The obtained graphene-like C3N4 exhibited a two-dimensional thin-layer structure with about 3–6 atoms thickness, a high specific surface area of 32.54 m2 g−1, increased photocurrent responses, improved electron transport ability and enhanced photocatalytic activity. The photocatalytic reaction for the organic dye methylene blue (MB) by the graphene-like C3N4 followed first-order kinetics. Moreover, the graphene-like C3N4 exhibited a higher apparent rate of 0.1262 min−1, which was 3.1 times higher than that of the bulk g-C3N4 (0.0409 min−1). The enhanced photocatalytic reaction was due to a high specific surface area and a larger bandgap (by 0.14 eV). The yield of the graphene-like C3N4 was up to ∼0.35 mg mL−1. Moreover, the graphene-like C3N4 had a new property that it could be used as the sensor for trace amounts of Cu2+ determination, so the graphene-like C3N4 is a new but promising candidate for heavy metal ions (Cu2+) determination in water environment. Photoelectrochemical selective sensing of trace amounts of Cu2+ was also discussed.

Construction of a 2D Graphene‐Like MoS2/C3N4 Heterojunction with Enhanced Visible‐Light Photocatalytic Activity and Photoelectrochemical Activity

A novel graphene-like MoS2 /C3N4 (GL-MoS2/C3N4) composite photocatalyst has been synthesized by a facile ethylene glycol (EG)-assisted solvothermal method. The structure and morphology of this GL-MoS2/C3N4 photocatalyst have been investigated by a wide range of characterization methods. The results showed that GL-MoS2 was uniformly distributed on the surface of GL-C3N4 forming a heterostructure. The obtained composite exhibited strong absorbing ability in the ultraviolet (UV) and visible regions. When irradiated with visible light, the composite photocatalyst showed high activity superior to those of the respective individual components GL-MoS2 and GL-C3N4 in the degradation of methyl orange. The enhanced photocatalytic activity of the composite may be attributed to the efficient separation of electron-hole pairs as a result of the matching band potentials between GL-MoS2 and GL-C3N4. Furthermore, a photocatalytic mechanism for the composite material has been proposed, and the photocatalytic reaction kinetics has been measured. Moreover, GL-MoS2/C3N4 could serve as a novel sensor for trace amounts of Cu(2+) since it exhibited good selectivity for Cu(2+) detection in water.

Synthesis of g-C3N4 at different temperatures for superior visible/UV photocatalytic performance and photoelectrochemical sensing of MB solution

In this paper, a simple preparation method was utilized to study for the optimum calcination temperature of graphitic carbon nitride (g-C3N4). The g-C3N4 prepared at different temperatures were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS) and so on. The results demonstrated that g-C3N4 could not be formed fully until the calcination temperature was higher than 500 °C. From DRS and photoluminescence (PL) spectrum, a red shift of absorption peaks with increasing calcination temperatures was found. This could enhance the visible light absorption, and then the photocatalytic activity would be improved. The photocatalytic activity was evaluated via the photodegradation of methylene blue (MB) and 4-chlorophenol (4-CP), respectively. Moreover, due to the gradual decrement trend of photocurrent intensity with addition of MB, g-C3N4 prepared at 650 °C could be used as a photoelectrochemical sensor to detect the existence of MB and estimate the concentration of MB. Hence g-C3N4 will become a promising candidate for photoelectrochemical applications.

A silver on 2D white-C3N4 support photocatalyst for mechanistic insights: synergetic utilization of plasmonic effect for solar hydrogen evolution

A photocatalyst integrating silver surface plasmon effect into two-dimensional g-C3N4 nanosheets (2D white-C3N4) was prepared successfully. The crystal structure, chemical states, morphology and photocatalytic performance of the prepared samples were researched by the comprehensive characterization methods. The photocatalytic activities of Ag/2D white g-C3N4 composites were dramatically enhanced under visible light irradiation. When Ag content was optimized, 2% Ag/white g-C3N4 exhibited the best photocatalytic activity. The electrochemical investigation verified the role of the hot electrons from the plasmonic Ag in the photocatalytic reaction. The plasmonic hot electron injection and advantages of 2D ultrathin structure improved the density of the electrons with reducibility and led to more efficient separation of photogenerated electron and hole pairs. The photocatalytic mechanism was also researched in detail via ESR analysis.

WO3 nanorod photocatalysts decorated with few-layer g-C3N4 nanosheets: controllable synthesis and photocatalytic mechanism research

Novel WO3 nanorod (WO3 NRs) photocatalysts decorated with few-layer g-C3N4 nanosheets (flg-C3N4) have been synthesized by a typical hydrothermal process. The structure, morphology, optical and electronic properties were researched by comprehensive characterization methods. The photocatalytic performance of flg-C3N4/WO3 NRs nanocomposites was assessed by degrading Rhodamine B (RhB) dye under visible light irradiation. When the loading amount of the flg-C3N4 is 20 wt%, the flg-C3N4/WO3 NRs nanocomposites exhibit the highest activity and the Chemical Oxygen Demand (COD) values decreased by about 64%. The improved light harvesting ability and higher separation efficiency of photoinduced electron–hole pairs by the decoration of flg-C3N4 lead to the boosting photocatalytic performance. In addition, through ESR analysis and a trapping experiment, the photocatalytic mechanism was also researched.

Construction of SnO2/graphene-like g-C3N4 with enhanced visible light photocatalytic activity

In this work, SnO2/graphene-like g-C3N4 (SnO2/GL-C3N4) composite photocatalysts with large surface areas and abundant coupling heterointerfaces were synthesized using a hydrothermal method. The as-prepared photocatalysts exhibited distinctly manifested efficient visible light activities toward organic pollutant degradation, demonstrating remarkable synergistic effects between SnO2 and graphene-like g-C3N4 (GL-C3N4). The 25 wt% SnO2/GL-C3N4 composite showed optimal photocatalytic activity under visible light irradiation, which was almost 9 and 2.5 times as high as that of SnO2 and GL-C3N4, respectively. In addition, the possible photocatalytic mechanism of rhodamine B (RhB) degradation by SnO2/GL-C3N4 under visible light was also discussed in detail. Moreover, this work would provide a facile way for the fabrication of novel two dimension/two dimension (2D/2D) GL-C3N4-based photocatalysts with high and stable performance for pollutant degradation.

Metallic 1T-TiS2 nanodots anchored on a 2D graphitic C3N4 nanosheet nanostructure with high electron transfer capability for enhanced photocatalytic performance

Photocatalysis is one of the most promising technologies for solar energy conversion. With the development of photocatalysis technology, the creation of low-dimensional structure photocatalysts with improved properties becomes more and more important. Metallic 1T-TiS2 nanodots with a low-dimensional structure were introduced into environmentally friendly two-dimensional g-C3N4 (2D-C3N4) nanosheets by a solvothermal method. It was found that the ultrathin TiS2 nanodots were uniformly anchored on the surface of the 2D-C3N4. The effective suppression of electron–hole recombination was realized due to the addition of the intrinsic metallic property of 1T-TiS2 in the prepared nanocomposite. The 5 wt% TiS2/2D-C3N4 nanocomposite exhibited the best photocatalytic performance and the degradation rate towards RhB was ca. 95% in 70 min, which showed an improvement of ca. 30% in comparison with 2D-C3N4. The results indicate that the obtained TiS2/2D-C3N4 nanocomposite is a promising photocatalyst for practical applications.