Jizhou Jiang

Use of Single-Layer g-C 3 N 4 /Ag Hybrids for Surface-Enhanced Raman Scattering (SERS)

Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.

Improving the surface-enhanced Raman scattering activity of carbon nitride by two-step calcining

We demonstrated a novel two-step calcining method for growing highly efficient surface-enhanced Raman scattering (SERS) substrates, modified g-C3N4. Their morphologies, microstructures and optical properties were successfully controlled by altering the calcining time. Moreover, the modified g-C3N4-2 h + Ag substrate exhibited superior SERS activity, suggesting its potential applications in SERS sensing.

NiO and Co3O4 co-doped g-C3N4 nanocomposites with excellent photoelectrochemical properties under visible light for detection of tetrabromobisphenol-A

Novel NiO/Co3O4/g-C3N4 nanocomposites with applications in photoelectrochemical sensing were designed and fabricated for the first time in this work. The morphology and microstructure of NiO/Co3O4/g-C3N4 were comprehensive investigated. The NiO/Co3O4/g-C3N4 nanocomposites exhibited higher photocurrent and donor density than those of pure g-C3N4, resulting in a higher photoelectrochemical activity for sensitive detection of TBBP-A in real water samples.

Fabry–Perot Cavity-Enhanced Optical Absorption in Ultrasensitive Tunable Photodiodes Based on Hybrid 2D Materials

Monolayer two-dimensional (2D) transition metal dichalcogenides (TMDs) show interesting optical and electrical properties because of their direct bandgap. However, the low absorption of atomically thin TMDs limits their applications. Here, we report enhanced absorption and optoelectronic properties of monolayer molybdenum disulfide (MoS2) by using an asymmetric Fabry-Perot cavity. The cavity is based on a hybrid structure of MoS2/ hexagonal boron nitride (BN)/Au/SiO2 realized through layer-by-layer vertical stacking. Photoluminescence (PL) intensity of monolayer MoS2 is enhanced over 2 orders of magnitude. Theoretical calculations show that the strong absorption of MoS2 comes from photonic localization on the top of the microcavity at optimal BN spacer thickness. The n/n+ MoS2 homojunction photodiode incorporating this asymmetric Fabry-Perot cavity exhibits excellent current rectifying behavior with an ideality factor of 1 and an ultrasensitive and gate-tunable external photo gain and specific detectivity. Our work offers an effective method to achieve uniform enhanced light absorption by monolayer TMDs, which has promising applications for highly sensitive optoelectronic devices.

Atmospheric Pressure Fabrication of Large-Sized Single-Layer Rectangular SnSe Flakes

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for applications in two-dimensional nanoelectronics devices. Although many methods to synthesize SnSe nanocrystals have been developed, a simple way to fabricate large-sized single-layer SnSe flakes remains a great challenge. Herein, we show the experimental method to directly grow large-sized single-layer rectangular SnSe flakes on commonly used SiO2/Si insulating substrates using a straightforward two-step fabrication method in an atmospheric pressure quartz tube furnace system. The single-layer rectangular SnSe flakes with an average thickness of ~6.8 Å and lateral dimensions of about 30 µm × 50 µm were fabricated by a combination of vapor transport deposition technique and nitrogen etching route. We characterized the morphology, microstructure, and electrical properties of the rectangular SnSe flakes and obtained excellent crystallinity and good electronic properties. This article about the two-step fabrication method can help researchers grow other similar two-dimensional, large-sized, single-layer materials using an atmospheric pressure system.

A Comparative Study of the Photoconduction, Photocatalytic and Electrocatalytic Performance of g-C3N4/ZnS/CuS Heterojunctions with Different Morphologies

Ternary heterojunctions g-C3N4/ZnS/CuS with different morphologies were constructed. The g-C3N4/ZnS/CuS (hexagonal-nanosheets) exhibited the largest photocurrent, the best photocatalytic and electrochemical activity, which revealed the influence discipline of different morphologies on photoconductivity, photo/electro-catalytic activity. It indicated that this heterojunction can be used as an excellent photoconductor device, a high-efficiency photo/electro-catalyst.Graphical Abstract