Ultrathin Graphdiyne Nanowires with Diameters below 3 nm: Synthesis, Photoelectric Effect, and Enhanced Raman Sensing

Interfacial Bonding Induced Charge Transfer in Two-Dimensional Amorphous MoO3-x/Graphdiyne Oxide Non-Van der Waals Heterostructures for Dominant SERS Enhancement

Two-dimensional semiconductor-based nanomaterials have shown to be an effective substrate for Surface-enhanced Raman Scattering (SERS) spectroscopy. However, the enhancement factor (EF) tends to be relatively weak compared to that of noble metals and does not allow for trace detection of molecules. In this work, we report the successful preparation of two-dimensional (2D) amorphous non-van der Waals heterostructures MoO3-x/GDYO nanomaterials using supercritical CO2. Due to the synergistic effect of the localized surface plasmon resonance (LSPR) effect and the charge transfer effect, it exhibits excellent SERS performance in the detection of methylene blue (MB) molecules, with a detection limit as low as 10-14 M while the enhancement factor (EF) can reach an impressive 2.55×1011. More importantly, the chemical bond bridging at the MoO3-x/GDYO heterostructures interface can accelerate the electron transfer between the interfaces, and the large number of defective surface structures on the heterostructures surface facilitates the chemisorption of MB molecules. And the charge recombination lifetime can be proved by a ~1.7-fold increase during their interfacial electron-transfer process for MoO3-x/GDYO@MB mixture, achieving highly sensitive SERS detection.

Exploring the Fate of Copper Ions in the Synthesis of Graphdiyne

Copper is a crucial catalyst in the synthesis of graphdiyne (GDY). However, as catalysts, the final fate of the copper ions has hardly been concerned, which are usually treated as impurities. Here, it is observed that after simple washing with water and ethanol, GDY still contains a certain amount of copper ions, and demonstrated that the copper ions are adsorbed at the atomic layers of GDY. Furthermore, we transformed in situ the copper ions into ultrathin Cu nanocrystals, and the obtained Cu/GDY hybrids can be generally converted into a series of metal/GDY hybrid materials, such as Ag/GDY, Au/GDY, Pt/GDY, Pd/GDY, and Rh/GDY. The Cu/GDY hybrids exhibit extraordinary surface enhanced Raman scattering effect and can be applied in pollutant efficient enrichment and detection.

Physical mechanism on the linear spectrum and nonlinear spectrum in a twist bilayer graphdiyne nanodisk

The one-photon absorption properties (OPA), two-photon absorption properties (TPA), electronic circular dichroism (ECD) spectra and partial DOS (PDOS) of a twist bilayer graphdiyne nanodisk (TwBLGDY-ND) were investigated by using a variety of quantum chemistry and wave function analyses. The physical mechanism of the twist bilayer graphdiyne nanodisk (TwBLGDY) with optical properties regulated by twisting angles was revealed. The results show that the twist angle makes the TwBLGDY form a moiré superlattice structure, and electron excitation mainly occurs in the first ring of the moiré superlattice structure. The contribution of atomic orbitals in these fragments to transition dipole moments is greater and electronic transitions are more likely to occur. When the twist angle increases from 0° to 15°, the absorption spectrum of the system is red shifted, which is mainly due to the enhancement of electron excitation characteristics. When the twist angle increases from 15° to 27.5°, the absorption spectrum of the system is blue shifted, due to the enhanced charge transfer within the layer. On the other hand, the twist angle can regulate the TPA absorption cross section of the system to enhance the intensity of the absorption spectrum. The twist angle can also regulate chirality by adjusting the spatial distribution of electric dipole transition and magnetic dipole transition. This study can provide theoretical guidance for constructing chiral optical devices based on the TwBLGDY structure.